How Many Years Can I Carry Forward Unused Federal Solar Tax Credits? + FAQs

You can carry forward unused federal solar tax credits for many years – homeowners can roll over their credit indefinitely, while businesses get up to 20 years (now effectively 22 years) to use remaining credits. In 2022, U.S. homeowners claimed over $9 billion in solar tax credits, yet many could not use the full amount in one year. If that sounds like you, don’t worry: your unused credit isn’t lost – it carries into future tax years, giving you ample time to benefit. Below, we’ll break down exactly how long you can carry forward your solar Investment Tax Credit (ITC) and how to make the most of it.

💡 Instant Answer Up Top: Discover the exact number of years you can roll over your unused solar tax credit – and why it’s virtually unlimited for homeowners but capped (at 20-22 years) for businesses!
🏠 Homeowners & Individuals: Learn how the residential solar credit carryforward works, why it doesn’t expire, and how to claim it using IRS Form 5695 each year until it’s fully used.
🏢 Businesses & Commercial Projects: Find out about IRS carryforward limits (20-year rule) for business solar credits, how the Inflation Reduction Act extended it to 22 years, and tips for managing credits alongside MACRS depreciation.
📑 IRS Rules, Forms & Reporting: Get a step-by-step on reporting unused credits – from understanding Section 25D vs. Section 48 of the tax code to filing Form 5695 (individuals) or Form 3468/3800 (businesses) so your credits roll over correctly.
⚖️ Laws, Loopholes & Updates: Stay updated on major legislation (IRA 2022) that changed solar credit rules, see how federal vs. state solar credits differ (carryover periods, refundability), and even peek at court rulings & IRS guidance confirming you won’t lose your credit.
🚫 Avoid Costly Mistakes: From misreporting carryforwards to forgetting recapture rules, we’ll highlight common pitfalls and how smart tax planning can help you maximize every dollar of your solar tax credit over time.

The Basics: What Happens to Unused Solar Tax Credits?

When you install a solar energy system, the federal government rewards you with a generous tax credit. This Investment Tax Credit (ITC) equals a percentage of your solar installation cost (currently 30% for systems placed in service 2022-2032). But what if the credit is larger than your tax bill? That’s where carryforward comes in.

Nonrefundable Credit: The federal solar ITC is a nonrefundable credit. In plain English, this means the credit can reduce your federal income tax to $0, but it can’t trigger a negative tax or refund beyond what you paid. If you owe little to no tax for the year, you won’t get a check for the unused portion. Instead, any unused amount becomes a carryforward to future years.

Carryforward (Carryover) Explained: Carryforward is essentially a rollover of your remaining credit. Rather than losing the benefit, you can apply the unused credit to offset taxes in future tax years. It’s like having store credit – if you can’t spend it all now, you save the balance for your next trip. The big question: How many years can you keep rolling it forward?

The good news: **Federal law allows you to carry forward solar credits for multiple years. In fact, for individual homeowners there’s no fixed time limit – you can keep carrying it forward indefinitely until it’s used up. For businesses, there is a time limit (historically 20 years, now extended to 22 years for newer projects). Let’s break down the rules by category, so you know exactly what applies to your situation.

Before diving deeper, remember that to actually use a carryforward, you must claim the credit on your tax return. That involves some IRS paperwork each year (we’ll cover how to do that later). Now, let’s explore the different rules for homeowners vs. businesses and how long each can carry over unused solar tax credits.

Homeowners: Unlimited Rollovers for Residential Solar Credits

For individuals and homeowners, the federal solar tax credit is covered under IRC Section 25D – often called the Residential Clean Energy Credit. If you installed solar panels (or other renewable energy like solar water heaters, small wind, geothermal, etc.) at your home, you likely qualify for this credit. One huge advantage for homeowners is that **any unused residential solar credit can be carried forward without an explicit year limit.

No Expiration for Individuals: In practice, homeowners can carry forward their solar credit indefinitely. There is no 5-year or 10-year cutoff – you simply roll the remaining credit into next year, and repeat as needed, until it’s gone. The IRS explicitly confirms this: if your credit exceeds your tax liability, you can apply the excess to future years. There’s no annual or lifetime cap on the credit amount for solar (aside from a separate limit for fuel cells), and no cap on the number of years for carryover.

Example: Suppose you went solar and earned a $10,000 tax credit, but your total federal tax owed this year is only $4,000. You would use $4,000 of the credit to wipe out this year’s taxes. The remaining $6,000 doesn’t vanish – it carries forward. Next year, if you owe, say, $3,000 in taxes, you can use $3,000 of the carried credit then (reducing that year’s taxes to $0), and still have $3,000 left to carry over again. You keep doing this until you’ve claimed the full $10,000. Even if it takes 3, 5, or 10+ years, the credit will still be waiting for you each year as a carryforward until fully utilized.

Why No Time Limit? The law (Section 25D) was written to encourage residential clean energy by making sure homeowners get the full value of the credit, even if it takes years. While the opportunity to earn new credits is scheduled to phase out after 2034 (with the credit percentage stepping down in 2033 and 2034), previously earned credits can still be used after that. The carryforward provision exists independently of the credit’s expiration for new systems. In other words, if you install solar in 2034 (when the last 22% credit is available) and have leftover credit, you can carry it into 2035 and beyond. There’s nothing in the law that says your carryover stops when the program sunsets – it remains valid.

IRS Guidance: The IRS has issued clear guidance confirming this unlimited carryforward. For instance, IRS Fact Sheet 2022-40 reiterated that under the Residential Clean Energy Credit, a taxpayer may carry forward the unused amount to future tax years. Similarly, IRS Notice 2013-70 clarified that there’s no cap on carryforward years for these credits. So rest assured – your unused solar credit won’t expire or disappear as long as you keep filing for it.

Filing Each Year: To actually claim the carryforward, you’ll need to file IRS Form 5695 (Residential Energy Credits) with your tax return every year that you have credit to use. Form 5695 has a section where you enter any “credit carryforward” from prior years. For example, if last year you couldn’t use it all, the form’s instructions will guide you to carry the remainder to the next year’s form. Essentially, you must re-claim the credit each year until it’s gone. Think of it like taking bites of a big pie over several years – you report each bite on that year’s tax form. The tax software or your accountant will typically keep track of the unused portion and roll it to the next return. Just don’t forget: if you have a carryforward, you must include Form 5695 each year to actually get that portion of the credit applied.

Tip: There’s no penalty for taking several years to use your credit. Some retired or lower-income homeowners worry they’ll “lose” the credit because their annual tax is small – but fear not. You could literally have $0 tax for several years in a row by using chunks of the credit, and any remainder just keeps rolling forward. There’s no interest or fee – it’s your money (or rather, your tax reduction) to claim when you can. Just keep track of it and use it up before you die (morbid but true: personal tax credits generally can’t be used after a person’s death, except possibly by a surviving spouse on a joint return for that final year).

In summary, for homeowners: the carryforward period is effectively unlimited. Your unused federal solar credit carries over year after year until it’s fully applied. The key is to file for it each year and stay within the rules (e.g. you must still own the system and owe taxes in those future years). Next, let’s look at how things differ for businesses and commercial solar projects.

Businesses: Carryforward Limits and Perks for Commercial Solar ITC

If you installed solar panels for a business, farm, rental property, or any commercial purpose, you’re dealing with the Business Energy Investment Tax Credit (the business ITC). This credit, codified in IRC Section 48, follows a different set of rules because it’s part of the general business credit system. One key difference: businesses do face a time limit on carryforwards (unlike individuals).

20-Year Carryforward (Now 22 Years): Under long-standing IRS rules, unused general business credits can be carried forward up to 20 years. Specifically, any unused portion of the solar ITC could be used in future years, up to twenty years after the year it was earned. Additionally – unlike personal credits – business credits also allowed a carryback to the previous year (originally a 1-year carryback). So a business with unused solar credits could amend last year’s return to get a refund (carrying back) or carry forward for 20 years.

Inflation Reduction Act Update: The Inflation Reduction Act (IRA) of 2022 expanded these rules for certain clean energy credits. For projects placed in service in 2023 and later, the IRA extended the carry period to 22 years forward (and 3 years back). In plain terms, a business that can’t use all its solar credit now can apply it to any tax year up to 22 years into the future (and even recoup taxes from the past three years). This is a boost from the old 20-forward/1-back rule, providing more flexibility. Congress made this change to ensure businesses fully benefit from new energy incentives – it’s part of making these credits more bankable and even transferable (more on that in a moment).

So today, businesses generally have a 22-year window to use unused solar credits, with the ability to also reach back three years if it helps. If any credit is still unused after 22 years, it would expire (though in practice, very few businesses will have solar credits lasting that long).

Example: Imagine a small business installs a solar array and earns a $50,000 ITC. In year 1, due to large deductions (maybe the business had low profit or used bonus depreciation), their tax liability is only $10,000 – so they use $10k of the credit and have $40,000 remaining. They carry the $40k forward. Over the next several years, the business can apply that $40k against its taxes. If in some year they have zero tax (perhaps a loss), the credit just continues carrying forward. They have up to 22 years to use the entire $50k credit. If by, say, year 10 they’ve used $45k and $5k remains, that $5k can still carry on. But if somehow $5k is still left after 22 years, that portion would expire. In practice, most businesses will utilize it within that timeframe, especially as their profitability grows.

Carryback Option: Businesses get an extra trick: carrying back unused credit to a prior year. If, in our example, the business had paid taxes last year, they could amend last year’s return and apply some of the credit backward to instantly get a refund of past taxes. The IRA expanded this to a 3-year carryback (formerly 1 year). This means a business can effectively “reach into the past” up to three years, which can be handy for smoothing out tax years – for instance, if you had a very profitable year two years ago and now have a big credit, you might carry it back to reclaim some of those past taxes paid.

Forms for Businesses: To claim the solar ITC for a business, you’ll use IRS Form 3468 (Investment Credit). This form calculates the credit for energy property under Section 48. The total then flows into Form 3800 (General Business Credit), which is where limitations are applied and where carryforwards/carrybacks are recorded. On Form 3800, you’ll see sections to input any credit carryforward from prior years as well as any carryback (if you’re applying it to a prior year’s liability). Essentially, if your credit exceeds your current year tax limit, the excess is noted as a carryforward that you can bring to future years’ 3800 forms. Keeping track of these figures is crucial for tax planning.

MACRS Depreciation Impact: One reason businesses often have unused solar credits initially is depreciation. Solar equipment qualifies for MACRS (Modified Accelerated Cost Recovery System) depreciation, typically over 5 years. Even more, for projects in recent years, bonus depreciation allowed businesses to deduct a huge chunk (even 100% in some years) of the solar system’s cost in the first year. While depreciation is a separate tax benefit (it’s a deduction, not a credit), it can drastically reduce a company’s taxable income. A company might show little to no taxable profit in the first year thanks to depreciation on the solar asset (plus other expenses). The result? Low tax liability, which in turn limits how much of the credit can be used immediately. Thus, a large portion of the credit gets carried forward.

Example scenario: A company spends $200,000 on a solar installation. It qualifies for a $60,000 ITC (30%). However, thanks to MACRS and bonus depreciation, the company also deducts a huge portion of the system’s cost, creating a net operating loss (NOL) or at least reducing taxes significantly. The credit is limited by the tax after deductions. If the company ends up with zero taxable income (an NOL), it can’t use any of the $60k credit that year – so the entire amount carries forward. In future years, as the company’s depreciation benefits taper off and taxable income rises, it will start using the credit. Net Operating Loss interplay: Note that if a business has an NOL carryforward, it uses that to offset future income before credits apply. So in some cases, credits might be further delayed until NOLs are utilized (since credits generally can’t create refunds beyond eliminating tax, and if an NOL makes taxable income zero, there’s no tax to offset with a credit). The bottom line is that business credits often stretch over multiple years due to these dynamics.

Passive Activity Limitations: If you own a solar project through a partnership or LLC and you’re not actively involved (for example, you invested in a commercial solar farm, or you put solar on a rental property), be aware of passive activity credit limitations. The tax law says you can generally only use passive credits (from passive business activities or rentals) to offset tax on passive income. So if you don’t have a lot of passive income each year, your solar ITC from that passive activity might not get used immediately – it becomes a passive credit carryforward. It will carry forward (up to the 20/22-year limit) until either you have passive income to absorb it or you dispose of the activity (selling the property can free up unused passive credits in the year of sale). This is a complex area, but it’s important for, say, landlords who add solar to a rental building. The credit is great, but you might only be able to claim it gradually if your rental income (passive income) is modest.

Credit Recapture Considerations: One more thing businesses must consider is the recapture rule. If you claim a solar ITC for a business asset, you are generally required to maintain that property for 5 years. If you sell or dispose of the solar equipment (or it ceases to be eligible property) before five years elapse, a portion of the credit must be paid back (recaptured) on your taxes. The recapture amount is prorated – for example, selling in year 2 might force you to recapture 80% of the credit, selling in year 4 might recapture 40%, etc. After 5 full years, no recapture. This matters for carryforward because if you still had unused credit carried and you dispose of the system, you may forfeit the remaining carryforward and even have to pay back some credit used. Always plan to hold the system at least five years if you’re taking the credit on a business return.

Transferability and Direct Pay (New Options): The Inflation Reduction Act introduced new wrinkles starting in 2023: credit transferability and direct pay (for certain entities). Transferability means a business can sell its tax credit to another taxpayer for cash. If a business has little tax liability and doesn’t want a long carryforward, it could sell the credit (often at a slight discount, like getting $0.88 on the dollar). The buyer of the credit can then use it on their tax return, and they get the same carryback/carryforward rights (3 back, 22 forward) for that purchased credit. This effectively monetizes the credit up front, so the original company doesn’t have to wait years to benefit. Direct pay allows tax-exempt organizations (and a few select others) to treat the credit as refundable – essentially receiving a payment from the IRS as if it were a refund, since they don’t have tax liability. While these are beyond the scope of a typical individual’s question, they are part of the business solar credit landscape now. For a standard taxable business, the key is: you have up to 22 years to use the credit, or you might choose to transfer it for immediate benefit.

In summary, businesses do have a long, but not unlimited, carryforward period. Historically it was 20 years, and with current laws it’s effectively 22 years forward (plus a possible lookback). This is plenty of time for most companies to absorb the credit, especially as profitability tends to grow over time. The expansion under IRA 2022 means it’s even less likely a credit will go unused. Businesses just need to file the right forms, track their carryforwards, and consider strategies (like carrybacks or transfers) to optimize the credit’s value.

Mixed-Use Properties: Splitting Credits Between Personal and Business

What if your solar installation isn’t purely personal or purely business? Many real-life situations fall in a gray area: mixed-use properties. This could include:

A home office in your residence (where part of your home’s solar powers a business use),
A duplex or multi-family home where you live in one unit and rent out the other,
A farm or bed-and-breakfast where the property serves dual personal and business purposes,
Or even solar on a property you partially use and partially lease out.

In mixed-use cases, you may be eligible for both the residential credit and the business credit, each on the respective portion of the system’s cost. The IRS has rules to determine how to split it.

The 80/20 Rule: The IRS guidance (and Form 5695 instructions) provide a simplification: If 80% or more of the solar system’s use is for personal residential purposes, you can generally treat the entire system as residential for the credit. In other words, minor business use (not more than 20%) won’t force you to split hairs – you could just claim 100% of the cost under the residential Section 25D credit. This is helpful for homeowners with a small home office or incidental business use; you likely can ignore the business aspect and take the full 30% credit on Form 5695.

However, if more than 20% is for business use, then you must allocate the expenses between residential and business. Only the portion allocable to personal use qualifies for the residential credit on your Form 5695. The portion allocable to business use could potentially qualify for the commercial ITC (Section 48) on a business tax return.

Example: You have a duplex; you live in one half and rent out the other half. You install a solar PV system that provides power to the whole building (both units). Let’s say the cost is $40,000. Because the property is 50% personal, 50% rental, you’d allocate the cost accordingly:

$20,000 is for your personal residence half,
$20,000 is for the rental half (business use).

You can claim a $6,000 residential credit (30% of the $20k personal portion) on your Form 5695. Meanwhile, you (or your LLC/partnership that owns the rental) can claim a $6,000 business ITC (30% of the $20k rental portion) on Form 3468/3800. Each portion then follows its own rules. The $6,000 personal credit follows the unlimited carryforward rule on your individual return. The $6,000 business credit follows the 20-year (or 22-year) carryforward on the business side. If the rental is a passive activity for you, that $6k business credit may only offset passive income tax; any excess carries forward under passive credit rules.

Home Office Scenario: If you install solar on your home which you use 30% for a home business (say you operate an office or daycare out of your home), 30% of the solar could be considered business use. Because the business use is >20%, you’re supposed to allocate. For simplicity, imagine the system cost $10,000. You’d allocate $7,000 to personal (70%) and $3,000 to business (30%). You then get a $2,100 credit on the personal side (30% of $7k) and a $900 credit on the business side (30% of $3k). Again, you’d file Form 5695 for the personal portion and Form 3468 for the business portion (likely through Schedule C if you’re a sole proprietor, or through an entity).

Be mindful: the business portion will require depreciation as well. If you claim the business ITC, you must reduce the basis for depreciation by half of the credit. For example, on that $3,000 business portion, after a $900 credit, you’d reduce the depreciable basis by 50% of $900 ($450). So you’d depreciate $2,550 of that cost under MACRS, etc. Meanwhile, the personal portion isn’t depreciable (personal assets aren’t depreciated) – but you got a credit on it without basis reduction (personal credits don’t require basis adjustment for your home). These details can get complex, which is why mixed-use solar really benefits from professional tax advice.

Claiming in Practice: Often, mixed-use credits are claimed by prorating the system cost. The IRS may expect you to use a reasonable method to allocate cost – usually based on the proportion of electricity used by each part (if separate meters) or square footage or some reasonable measure of usage. In audits, they might look at whether your allocation is fair. If 50% of the power feeds a rental unit, using 50% allocation is sensible. If your home office is 10% of your house area, one might argue 10% business use (which falls under the 20% threshold, meaning perhaps you could avoid splitting at all if under 20%).

Carryforward in Mixed Situations: The carryforward mechanics remain the same for each portion. You’ll track the personal credit carryforward separately on your personal tax returns. And you’ll track the business credit carryforward within the business’s tax filings. There is no “mixing” of the two – they are different credits under different code sections, even though they arose from one solar installation. If the personal portion gets used up and the business portion still lingers (or vice versa), that’s just how it goes. Each lives on its own timeline.

Watch Out for Passive Limitations: In our duplex example, the $6,000 rental credit is likely limited by passive activity rules (unless you qualify as an active real estate professional or the rental is not treated as passive for some reason). If you have no passive tax liability that year, that $6k will carry forward to future years, waiting until you either have passive income or dispose of the rental property (at which point any unused credit might be freed up in the disposition year). This means potentially you could carry that rental portion credit for many years (even beyond 22 in theory if passive limitations delay it – though formally the credit carryforward can expire after 22; it’s a bit of a race condition between passive rules and credit expiration).

Example Outcome: Let’s illustrate a mixed-use carryforward scenario combining the above points:

Tax Year	Credit Usage (Personal vs. Business Portions)
2023 (Install year)	Personal portion: $2,100 credit earned. Homeowner’s tax was $500, so they use $500 and carry forward $1,600. Business portion: $900 credit earned. Rental had passive loss (no tax), so entire $900 carries forward under passive credit rules.
2024	Personal: uses $500 of carryforward (tax owed $500), carries $1,100 to 2025. Business: rental has $300 passive income tax, uses $300 of credit, carries remaining $600 forward.
2025–2030	Personal: uses $500 each year until exhausted by 2026 (the last $100 used in 2026). Business: continues to carry forward $600 until rental generates enough passive income – assume by 2027 rental income grows and the $600 credit is finally used that year.
Beyond	Personal credit fully used by 2026 – no carryforward remains. Business credit fully used by 2027. Both portions were utilized within allowed time (the business credit was used within 4 years, well under the 22-year limit).

In reality, your numbers will vary, but the table above shows how each portion’s credit is tracked and applied separately over years.

Key Takeaway: For mixed-use solar, you may have to split the credit and abide by two sets of rules. It’s a bit more legwork, but you still get the benefits – just proportionate to each use. Always ensure you correctly allocate and keep documentation (like usage calculations or an accountant’s worksheet) in case the IRS ever inquires. And consider consulting a tax professional to navigate any tricky parts, especially if you’re dealing with passive activity rules or basis adjustments.

How to Claim and Carry Forward Unused Credits (IRS Forms & Steps)

Knowing the rules is one thing – filing the paperwork is another. To actually realize the benefit of carryforwards, you need to claim your solar credits properly on the appropriate IRS forms. Let’s go through the process for both individuals and businesses, and highlight how you report carryover credits in subsequent years.

For Individuals (Homeowners) – Form 5695

IRS Form 5695, Residential Energy Credits is the form used by individual taxpayers to claim the residential solar credit (and certain other home energy credits). It’s usually attached to your Form 1040 when you file your annual taxes.

Initial Claim: In the year you first install and place the solar system in service, you’ll fill out Form 5695 to calculate the credit. You’ll enter the total qualifying costs of your solar installation (after any rebates or subsidies that require subtraction – e.g., utility rebates must be subtracted from cost). The form then multiplies by 30% (for systems 2022-2032) to get your credit amount. That credit is limited by your tax liability (Form 5695 has you input your tax from Form 1040 to apply the limitation). If your credit is larger than your tax, the form will show that not all credit is used.

Carryforward on Form 5695: Form 5695 includes a line for “Credit carryforward to next year.” Essentially, after you apply what you can to this year’s taxes (bringing your tax down to zero ideally), any leftover credit is calculated and recorded. For example, if your credit was $6,000 and you used $4,000 this year, the form will show a $2,000 carryforward. You don’t get a refund for that $2,000 – you’ll carry it to next year’s return.

Subsequent Years: Next year, when you do your taxes, you’ll again include Form 5695. There is a section where you input any “unused credit from prior years.” The $2,000 in our example would be entered there (often the tax software will do this automatically if you transfer last year’s data; or if doing by hand, you’d carry it from last year’s form). That amount is then treated as if it’s a new credit for the current year – it gets applied to your tax liability. If you still don’t have enough tax to use it fully, it will carry forward again.

This process repeats until the carryforward is fully used. The form instructions will spell out the line numbers for carryforwards. As of recent versions, it involves lines in the worksheet part of Form 5695 where you calculate the allowable credit.

One-Time Credit vs. Multi-Year Claim: It’s worth noting, you only earn the credit in the year you place the system in service. The carryforward isn’t “earning again,” it’s just using the remaining earned credit. But from a filing perspective, you will fill a Form 5695 for each year that you have any credit to claim – either new or carryover. This is different from something like a carryforward of a deduction or loss, where there might be separate schedules – here it’s all through the same credit form each year.

Watch the Phase-Out/Termination Dates: The residential credit in law currently terminates for property placed in service after 2034 (with phase-down percentages in 2033 and 2034). However, on the form, you’ll still be able to carry forward credits beyond those years if they were earned prior. For example, the 2035 Form 5695 (not yet existing, but likely) would still have a line for unused credits from earlier years. Just ensure you keep your documentation from the installation year because you might be referencing that original credit amount many years later.

Amending Returns for Carrybacks: Individuals cannot carry back the residential solar credit to previous years. So you won’t be amending old returns to use it – that option is only for business credits. If you realize you had an unused credit in a prior year that you didn’t carry forward correctly, you might need to amend that prior return’s Form 5695 to fix the carryforward number. But you can’t apply it to a year before the installation.

Recordkeeping: Hold onto a copy of your Form 5695 each year, especially the first year. If you use a tax preparer or software, make sure the carryforward number is correctly brought into the next year. If you switch tax preparers or software, double-check that the new one knows about your carryover. It’s easy to forget you have credit left if, say, several years pass. The IRS doesn’t send reminders; it’s on you to claim it.

For Businesses – Form 3468 and Form 3800

Businesses (including landlords, self-employed individuals claiming the credit on business property, and even third-party owned systems in some cases) will use the Investment Credit Form 3468.

Form 3468 (Investment Credit): This form is where you detail the eligible energy property and calculate the credit amount. It has sections for various types of credits (rehabilitation credit, energy credits, etc.). Solar projects fall under the energy credit category. You’ll enter the cost basis of the solar property and compute 30% of that (or the applicable percentage if it’s a later year or if specific bonus credits apply, etc.). The form will yield the total credit amount for that tax year’s projects.

For example, you installed a solar array for your business in 2025 costing $100,000, meeting all requirements. On Form 3468, you’d list that and calculate a $30,000 credit.

Form 3800 (General Business Credit): The credit from Form 3468 doesn’t directly reduce your taxes until it goes through Form 3800. Form 3800 aggregates all your business credits (R&D credit, solar ITC, etc.) and applies the overall limitations (such as not exceeding your net tax, alternative minimum tax rules if any, etc.). On Form 3800, there are lines to input:

Current year business credits (from Form 3468 and any other credit forms),
Carryforward of business credits from prior years,
Carryback of business credits if you are carrying back,
And the total allowable credit this year.

Claiming Carryforward: If you had a carryforward from a prior year (say you installed solar in 2023 but couldn’t use it all, and now in 2025 you still have some left), that carryover amount should be reported on Form 3800 in the carryforward section. Typically, there is a “General Business Credit carryforward” line. The instructions for Form 3800 provide where to include any carryforward (and carryback) amounts. These come from records or the IRS notice you might have received if you carried back (for carrybacks, the IRS typically issues a notice of your remaining credit when you do a carryback refund claim).

Using the Credit vs. Carrying It: Form 3800 will compute how much of the total available credit you can actually use this year. If your credits exceed the tax limit (for business credits, generally you can’t reduce your regular tax below any applicable AMT and can’t exceed a certain percentage of tax; though these rules have been liberalized, sometimes a tentative minimum tax can limit usage), then some credit remains unused. Form 3800 will then show that unused portion as a carryforward to next year (and/or carryback to prior year if you choose and are able).

Electing Carryback or Not: With the new 3-year carryback provision, a business can decide if it wants to carry back this year’s unused credit to prior years. If you decide to carry back, you’d typically file an amended return or a special form (Form 1139 for corporations, or Form 1045 for individuals with business credits) to claim a refund for those earlier years. Whatever remains after any carryback would then be carried forward. If you don’t carry it back, the full amount carries forward. There is often an option to elect to forgo the carryback and just carry everything forward (for simplicity or if prior years wouldn’t benefit). Check the Form 3800 instructions or Form 3468 instructions – they sometimes require an election statement if you want to skip the carryback. Make sure to make that election if you intend to only carry forward.

Tracking Over Years: Keep a schedule of your business credit carryforwards. Unlike personal credits which you might handle on one tax return at a time, business credits could involve multiple forms (especially if your business is a pass-through entity like an S-corporation or partnership – they’ll send you a K-1 with your share of the credit, and you’ll then use Form 3468/3800 on your personal return to claim it). Each year, update the remaining carryforward. For instance, if in 2024 you had $10,000 unused and you used $4,000 in 2025, you should have $6,000 to carry into 2026. It’s up to you (or your accountant) to maintain this record.

Passive Business Credits: If your solar project is held in a partnership or LLC and you’re a passive investor, your share of the credit might be limited on Form 3800 by passive activity rules. There is a specific form, Form 8582-CR, for Passive Activity Credit Limitations. Essentially, that form will determine how much of certain credits you can use if you have passive losses/credits. Any disallowed passive credit becomes a carryforward to the next year (still subject to passive limits). You would track those similarly, but note they’re also subject to the 20-year (22-year) limit from the year they arose. If you have carryforward passive credits for too long without passive income, they could eventually expire. This is an advanced nuance, but important for those in syndicated solar investments or rental property owners.

State Tax Forms: Don’t forget, if your business solar project is in a state with its own tax credit, you’ll also have separate forms for state carryforwards. These don’t affect your federal, but you want to manage them concurrently. Each state has different forms and rules (more on that soon).

Summary: Claiming and carrying forward solar credits on tax forms is a multi-year process:

Year of install: File Form 5695 (individual) or Form 3468 (business) to claim the credit, and Form 3800 if business, to apply limits.
Subsequent years: File the same credit form each year to utilize the carryforward. (Form 5695 for personal, showing prior carryforward; Form 3800 for business, with carryforward).
Keep documentation: Save copies of those forms, plus any IRS communication if you did carrybacks or if there were any changes on audit.

By diligently following the IRS forms and instructions, you ensure your carryforward is preserved and utilized. Missing a form or a line could mean leaving money on the table. But as long as you include the carryforward amount each year, the IRS will allow it to reduce your tax liability that year.

Next, let’s step back and look at the bigger picture: how these rules came to be, and how recent laws have shaped the solar tax credit landscape.

Legislative Background: How Congress Shaped the Solar Tax Credit

Understanding carryforward rules is easier with a bit of historical context. The ability to carry over credits isn’t arbitrary – it was built into the tax code by Congress to encourage long-term investment in renewables. Let’s explore the evolution of the solar ITC and the major legislative changes (including the game-changing Inflation Reduction Act of 2022) that influence how long and how much credit you can claim.

Origins of the Solar ITC: The concept of tax incentives for solar isn’t brand new. The Solar Investment Tax Credit in its modern form was established by Congress in the Energy Policy Act of 2005. It initially provided a 30% tax credit for solar installations, available for tax years 2006 and 2007. For homeowners, there was a cap ($2,000 max credit in those early years), whereas businesses had no cap but could only take the credit against the alternative minimum tax in limited ways. Even then, the credit was nonrefundable and eligible for carryforward if unused (with businesses under general credit rules, and individuals – the law allowed carryforward of the personal credit as well).

Extensions and Expansion: The solar credit proved popular and effective at spurring industry growth. Congress extended it multiple times:

In 2008, the Emergency Economic Stabilization Act (the bank bailout bill) extended the ITC for 8 years and removed the $2,000 cap for residential systems (beginning in 2009). This was huge for homeowners – now you could get the full 30% of a big system. The carryforward for residential became more relevant since credits could be much larger.
This extension set the credit at 30% through 2016.
In 2015, as the expiration loomed, a bipartisan deal (as part of a budget bill) extended the credit again: 30% through 2019, then stepping down to 26% for 2020, 22% for 2021, and then ending for residential in 2022 (business would drop to a permanent 10% after 2021).

The 2019-2020 Phase-Down Delay: In late 2020, Congress gave a last-minute short extension: the Consolidated Appropriations Act, 2021 kept the credit at 26% for 2021 and 2022, with 22% in 2023. So as of early 2022, it appeared the residential credit would drop to 0% in 2024 (and business to 10% in 2024), meaning 2023 was the last year for reduced credits.

Inflation Reduction Act of 2022: Then came a massive policy shift. In August 2022, the IRA was signed into law. This law revived and supercharged the solar tax credit:

It raised the credit back to 30% for installations from the start of 2022 through 2032 (yes, it retroactively made 2022 a 30% credit year again).
It extended the availability: 30% through 2032, then 26% for 2033, 22% for 2034, and ending in 2035 for residential (business credits would revert to 10% unless further extended, but likely future Congresses will address that).
It renamed the residential credit to “Residential Clean Energy Credit” (Section 25D now using that label) and made tweaks like adding battery storage as eligible property (from 2023 onward).
Importantly for our topic: the IRA expanded carryback/carryforward periods for business credits (as discussed, to 3-year carryback and 22-year carryforward) and introduced transferability and direct pay options to improve credit monetization.

The IRA essentially guaranteed that solar incentives will be around for a long time, and it addressed the very issue of unused credits by giving more ways and more time to use them. Lawmakers recognized that some entities, especially those without big tax liability (e.g., start-ups, nonprofits), struggled to use the credits fully. So now a business can sell the credit (so it doesn’t have to carry it for decades), or a nonprofit can take direct pay (which is like a refund). And if a regular business still wants to carry forward, it has 22 years to do so.

Why 20 Years (and now 22)? The 20-year carryforward for business credits has been in the tax code for decades (Section 39 of the Internal Revenue Code governs carryforwards of general business credits). The rationale is to allow businesses with cyclical or initial losses to still benefit from credits when they do become profitable – but also to not let credits linger forever (perhaps to limit long-term revenue uncertainty for the Treasury). By extending it to 22 years specifically for renewable energy credits, Congress essentially said: we’re giving even more runway, likely recognizing that clean energy projects often have upfront costs and slow initial returns.

For individuals, Congress never imposed a specific year limit in the statutory language for the residential credit’s carryforward. It simply says unused credit is carried to the next taxable year. By not capping it, the interpretation (supported by IRS) is that it can continue onward. This aligns with how some other personal credits work too, such as adoption credits (which have carryforwards that can extend 5 years by law, in that case, or education credits which don’t carry at all). In the case of solar, they chose an open-ended approach, which is taxpayer-friendly.

Notable IRS Clarifications: Over the years, the IRS has issued notices and Q&As to clarify aspects of the solar credit:

IRS Notice 2013-70 addressed frequently asked questions on the residential energy credits, confirming among other things that carryforward is allowed until used (even past credit expiration dates).
The IRS also clarified issues like when a solar installation is considered “placed in service” (you generally must have the system operational to claim the credit for that year, which matters for timing).
In 2022, the IRS Fact Sheets updated the public on IRA changes, including restating that excess credits carry forward to future years if not used.

Court Rulings: There haven’t been major court cases specifically about carryforward of the solar credit (since the law is pretty straightforward on that). However, there have been tax court cases on related topics:

Cases dealing with basis and subsidies (e.g., whether certain state incentives reduce the cost basis for the federal credit – often they do if it’s a rebate).
Cases on business vs personal use – for example, if someone tried to claim a commercial credit on a personal home or vice versa incorrectly.
Partnership tax credit schemes – the IRS has litigated cases where solar credits were sold or allocated improperly (before transferability was legal, some deals tried to effectively transfer credits via partnership allocations – some of those were struck down if not done according to rules).

None of these cases changed the fundamental ability to carry forward the credit, but they reinforce that one must follow the technical rules to validly claim the credit. For instance, one tax court case (Goforth v. Commissioner, 2020, as a hypothetical example) might deal with a couple who leased solar panels and tried to claim the credit (spoiler: if you lease, the credit stays with the lessor/company, not the homeowner). This is a common misunderstanding – only the owner of the system can claim the credit, so if you sign a lease or power purchase agreement, you typically are not eligible (the solar company would be). That’s not about carryforward per se, but it’s a legal definition aspect that sometimes ends up in disputes.

MACRS and Section 50(d): Historically, some laws interplay with credits – for example, if a business claims an ITC, Section 50 reduces the depreciable basis (half-credit rule mentioned earlier). There used to be something called the Section 1603 Grant (during 2009-2011, businesses could take a Treasury cash grant in lieu of the credit) – if a business did that, obviously then no credit to carry forward. But those grants are no longer available; we’re fully back to credits now.

Economic Impact: The solar ITC has been credited (pun intended) with driving massive growth in the renewable energy sector. According to the Solar Energy Industries Association (SEIA), since the ITC’s inception in 2006, U.S. solar deployment grew by over 10,000%. It’s created hundreds of thousands of jobs and tens of billions in investment. Congress’s willingness to extend and expand the credit (and allow flexible use via carryforwards) reflects its success. Lawmakers from both sides have supported it over the years. The IRA 2022 is perhaps the strongest commitment yet, locking in a full decade of policy certainty for solar.

Future Changes: Could the carryforward rules change again? It’s possible but not likely in the near term. The 22-year forward, 3-year back was specifically tied to the new energy credits. Unless altered by future legislation, that’s the regime for projects through at least the early 2030s. If anything, Congress might extend the credit availability window (beyond 2034) as deadlines approach. But if you have carryforward today, count on being able to use it in the coming years under current law.

In short, the legal landscape has consistently favored allowing taxpayers ample time to benefit from solar tax credits. The combination of IRS code, regulations, and periodic legislative tweaks works in your favor to ensure that neither individuals nor businesses lose out simply because they couldn’t use the credit in the installation year. With that backdrop, let’s examine how state-level solar incentives can differ from federal rules, since many solar owners also take advantage of state credits.

Federal vs State Tax Credits: Key Differences and Nuances

While we’ve focused on the federal solar tax credit, many U.S. states offer their own incentives, including state tax credits for solar installations. It’s important to realize that these state credits are completely separate from the federal ITC – different rules, different carryforward periods, and different eligibility criteria may apply. Here’s how state credits can differ and what to watch out for:

State Tax Credits 101: Some states give a tax credit (against state income tax) for installing solar on your home or business. These credits vary widely:

Credit Percentage or Amount: For example, New York provides a 25% state tax credit for residential solar, capped at $5,000. South Carolina offers a 25% credit capped at $3,500 per year. Maryland had a flat $1,000 credit (recently expired). Arizona offers a one-time credit up to $1,000 for residential solar. These are just a few examples – each state has its own formula and limits.
Carryforward Periods: Unlike the federal indefinite (for individuals) or 20-year rule (for business), states often set specific carryforward periods, often shorter. For instance:
- New York: If your NY solar credit exceeds your state tax due, you can carry forward the excess for up to five years. So if you can’t use that full $5,000 in one year, you have five subsequent years to use it.
- South Carolina: The SC credit is capped at $3,500 per tax year, but you can carry forward unused credit for up to 10 years. For example, a large solar system might earn a $10k SC credit – you’d use $3.5k in year 1, $3.5k in year 2, $3k in year 3 to fully utilize (provided you have enough tax each year), and SC law lets you stretch it up to 10 years if needed.
- Massachusetts: MA offers a 15% credit up to $1,000. If you can’t use the full $1,000 (say your MA tax was only $600), you can carry forward the remainder for up to 3 years.
- Hawaii: Hawaii historically had a very generous credit (35% of cost) but with certain caps per system; notably, Hawaii allowed unused renewable energy credits to be refundable at a reduced rate or carried forward 5 years. (Hawaii’s rules have changed a bit over time and became complex with caps, but generally they have a carryforward as well).
- Iowa: Iowa had a state solar credit that piggybacked on the federal (15% of the federal credit) with its own aggregate cap; any excess could carry forward for 1 year (but that program sunsets in 2021).

The key is each state decides its own carryforward duration – often it’s around 5 years, some longer, some shorter. No state we know of allows indefinite carryforward; they usually specify a term (likely to avoid very long-tail liabilities on their budget).

Refundable vs Nonrefundable: A huge difference: Some state credits are refundable or partially refundable, whereas the federal solar credit is not refundable. Refundable means if the credit exceeds your tax liability, the state will pay you the difference as a refund. This is relatively rare for solar credits, but it exists:

New Mexico had a solar credit that was refundable (up to a certain annual program cap).
Louisiana in the past offered a refundable credit (it actually sent checks, which at one point led to budget issues and the program was halted).
Some states like Massachusetts treat their $1,000 credit as nonrefundable but almost everyone has at least some tax to use $1k, so effectively it gets used (and they allow carryover 3 years if needed).
South Carolina’s credit is nonrefundable (hence the multi-year carryforward).

State Credit Interaction with Federal Tax: It’s important to note that a state tax credit can indirectly affect your federal taxes:

If you claim a state income tax credit, you typically pay less in state income taxes. If you itemize deductions on your federal return, your state tax deduction is lower (since you paid less tax). This could slightly increase your federal taxable income (because you can’t deduct taxes you didn’t pay). However, since 2018, the SALT (State and Local Tax) deduction on federal returns is capped at $10,000, so many taxpayers aren’t deducting all their state tax anyway. Regardless, this is a minor consideration – just a reminder that state credits may have a ripple effect on other parts of your tax situation.
Another interaction: If a state or utility gives you a rebate (not a credit) at installation, that rebate reduces the cost basis for claiming the federal credit. For example, if a state gives a $5,000 upfront rebate for solar, and your system cost $20,000, you must subtract that and claim 30% of $15,000 for the federal credit. But if a state gives a tax credit instead, you do not subtract that from your federal credit basis. Tax credits don’t reduce the cost basis of the property for federal purposes (as clarified by IRS guidance), whereas subsidies or rebates do. Thus, state credits are sweet because they don’t diminish your federal credit, they’re an added bonus.

Double Dipping and Timing: You can typically claim both federal and state credits in the same year. State forms often ask for information about the system to ensure you qualify. They also often require that the system is certified or installed by certain contractors, etc. Always check state-specific requirements (some require applying for the credit with a state agency first).

Examples to Illustrate State Differences:

New York Example: A NY homeowner spends $20,000 on solar. Federal credit = $6,000 (30%). NY credit = $5,000 (25% but capped at 5k). If their NY state tax for the year is only $3,000, they’ll use $3k of the NY credit and carry $2k forward (up to 5 years allowed for that $2k). On federal, if their federal tax was, say, $5,000, they use $5k of the $6k and carry $1k forward (indefinitely). So they have both a state carryforward and a federal carryforward to track, each with its own rules.
South Carolina Example: SC homeowner spends $40,000 on solar. Federal credit = $12,000. SC credit = $10,000 (25% of cost, but $3,500/year max). If their SC tax is $4,000 a year, they can claim $3,500 of credit each year for maybe 3 years (3,500 + 3,500 + 3,000) to use it up. But SC only allows up to 10 years, which is fine here since they needed 3. For federal, if their tax is small, they’ll chip away at $12k over however many years, no set limit.
Business State Credits: Some states also have business solar credits or grants. For example, Hawaii and Iowa had credits applicable to businesses too. These often can be claimed in addition to federal, but one must be careful about interactions. A state credit for business might or might not be considered taxable income for federal purposes (generally, a state tax credit is not taxable income, but if you get a state rebate or something, that could be income or reduce basis).

Navigating Different Rules: The main takeaway is that state incentives will have their own carryforward provisions that are usually shorter than the federal allowance. Always refer to your state’s tax credit statute or guidance:

Check if the state credit is refundable or nonrefundable.
If nonrefundable, check how many years you can carry it forward.
Mark your calendar or notes with that expiration. You don’t want to lose a state credit by forgetting to use it within its allowed period.
Also note if the state credit has an overall program cap (some states limit the total credits given out per year – if you apply late, you might get waitlisted).

Coordination of State and Federal: There is no direct legal dependency (the IRS doesn’t care if you took a state credit, and states don’t typically reduce their credit if you took federal). They operate independently. But for your financial planning, think of them together – they both lower your cost of going solar. For example, in New York a $20k system effectively costs you ~$9k after a $6k federal and $5k state credit (assuming you can utilize both fully over time). That’s a huge incentive stack.

Don’t Forget Other Incentives: States and localities also have rebates, property tax exemptions, sales tax exemptions, and net metering benefits. These aren’t credits on taxes, but they can affect your overall savings. A comprehensive plan would consider:

Upfront rebates (which reduce purchase cost, thus reducing the federal credit basis).
State tax credits (which might come when you file state taxes).
Ongoing benefits like selling Solar Renewable Energy Certificates (SRECs) or performance-based incentives.
These don’t directly affect the carryforward topic, but it’s good to be aware of the full picture of solar incentives.

Federal vs. State Summary: Federal gives you a long runway (no limit for personal, 22 years for business) to use solar credits, but it won’t cut you a refund check for unused credit. States might give you shorter runways (e.g. 5 years), but some will actually pay you if you can’t use it (refundability). Always read your state’s rules or consult a local tax expert. The combination of federal and state credits can drastically reduce the cost of your system – just be organized in how you claim each and track their carryforwards.

Now, let’s weigh the overall advantages and disadvantages of carrying forward solar tax credits, to put this strategy in perspective.

Pros and Cons of Carrying Forward Your Solar Tax Credit

Carrying forward unused solar credits is generally a positive feature, but it comes with some considerations. Here’s a quick overview of the benefits and drawbacks of the carryforward mechanism:

Pros 🟢	Cons 🔴
Full Value Preservation: You don’t lose the credit just because your tax liability is low in one year. Carryforward ensures you eventually reap the full value (maximizing your return on the solar investment).	Delayed Benefit: You must wait to get the financial benefit. It might take years to fully realize the credit’s savings, which isn’t as good as getting it all upfront. In the meantime, it’s essentially money locked up.
Flexibility in Tax Planning: Carryforwards allow you to plan ahead. For individuals, you could adjust income strategies (e.g., Roth conversions, stock sales) in future years to utilize credits. Businesses can plan to use credits in profitable years or carry back to past profitable years.	Risk of Expiration (Businesses): For commercial credits, there’s a time limit (20/22 years). In a prolonged downturn, a business could potentially forfeit some credit if it doesn’t have enough tax liability in that window (though 22 years is a long time). Personal credits technically could be lost if never used (e.g., if someone never has tax liability again for the rest of their life, unused credit would die with them).
No Cap on Home Credit Usage: Homeowners can use the carryforward as long as it takes – even if it’s 15-20 years, the law permits it. This is a huge pro for retirees or low-income households that go solar; they won’t miss out on the credit due to low taxes.	Annual Effort Required: You have to remember to claim the carryforward each year. Forgetting or misplacing records could lead to lost credit. It’s an administrative hassle over multiple tax filings, and errors could occur if not careful (especially with changing tax preparers).
Potential to Combine with Future Tax Strategy: If laws change to make the credit refundable or transferable for individuals (not currently the case, but one can hope), having a carryforward could allow you to take advantage of new options. For businesses, new rules like transferability mean you can decide to monetize future carryforwards by selling them. The carryforward keeps your options open.	Changes in Law Uncertainty: While carryforwards are allowed under current law, future Congresses could alter how credits are treated. (Unlikely they’d retroactively cancel carryforwards, but tax law does change.) There’s also the consideration that if tax rates or your personal situation change (e.g., moving to a no-income-tax state), the value of the credit carryforward could shift.
No Interest or Penalty: There’s no cost to carrying forward a credit – the IRS doesn’t charge anything or reduce its value over time (unlike some deductions or losses that might lose real value if the tax code changes inflation etc.). The credit you carry retains the same dollar value in the future.	Opportunity Cost: If you have to carry forward, it means you didn’t get the maximum benefit immediately. The money you save on taxes in future years is money you could have saved or invested earlier if the credit were usable sooner. In other words, spreading savings over years might reduce the net present value of the incentive slightly (inflation erodes value over time).

In essence, the pros of carryforward far outweigh the cons for most people. It’s a safety net provision – better to use a credit later than not at all. But it does introduce some complexity and delay. To mitigate the cons:

Stay organized: keep track of carryforwards diligently.
Try to accelerate benefit when sensible: for instance, a business might opt to carry back for an immediate refund, or an individual might strategically generate some taxable income (sell some appreciated stock, convert a bit of IRA to Roth, etc.) to utilize a credit in a year where they have a big carryover. This way, you get the cash value sooner.
Be mindful of expiration: if you’re nearing the end of a carryforward period (for business credits) and still have unused credit, it might be worth consulting a tax advisor for ways to use it up (for example, maybe merging businesses or increasing income in that year artificially).

Now that we’ve covered the technicalities and weighed the pros/cons, let’s ensure you avoid common pitfalls that taxpayers encounter with solar tax credits and carryforwards.

Avoid These Common Mistakes

Even with good rules in place, there are some common mistakes and misconceptions that can trip you up when dealing with solar tax credits and their carryforward. Here’s a list of pitfalls to avoid, so you can smoothly maximize your credit:

Assuming the Credit is Refundable: Many first-time filers mistakenly believe that if the solar credit exceeds their taxes, the IRS will send a refund check for the difference. This is wrong. The credit is nonrefundable – you won’t get a refund for the unused portion in the year of installation. Don’t bank on an immediate payout; plan for a carryforward if your liability is low.
Forgetting to Claim the Carryforward: It’s surprisingly easy to forget about your leftover credit in subsequent years, especially if a few years pass. Some taxpayers change accountants or software and the new preparer doesn’t know about the prior credit. Always carry your credit forward on Form 5695/3800 each year. Make a note in your tax files or a reminder each year until it’s used. If you failed to carry it forward and missed using it, you might need to amend returns to fix that – which is a hassle and could cost you if you miss the amendment window.
Misreporting Business Credit on Personal Return (or vice versa): If you’re a sole proprietor who installed solar for your business or you have a rental property, be careful to use the correct form. A mistake would be trying to claim a business credit on Form 5695 or a personal credit on Form 3468. Mixed-use allocations can also be done wrong. Misplacing where to claim can lead to IRS letters or disallowed credits. Follow the allocation rules and use the proper forms for each portion.
Not Using Carryback for Businesses: If you have a sizable unused credit on your business and you paid a lot of tax in prior years, don’t forget the carryback opportunity (especially with the new 3-year carryback). Failing to carry back when beneficial means waiting for no reason. You could get cash in hand by amending a prior year. Conversely, if you prefer carryforward, remember to elect out of carryback if required. It’s a mistake to leave money on the table that could be refunded from a past year.
Ignoring Passive Credit Limitations: If your solar project is part of a passive activity (like a rental), don’t overlook the passive limitation rules. Some folks will see a credit on a K-1 and assume they can use it fully, only to find out the IRS disallowed it due to no passive income. Work with a tax advisor to navigate Form 8582-CR. If a credit is being limited, understand that it’s carried forward (not gone), but you need to track it. A mistake here is thinking you’ve used the credit when actually it’s suspended in limbo. Know your status: active or passive.
Confusing State and Federal Credits: Another mistake is mixing up state and federal rules. A taxpayer might incorrectly assume their federal carryforward is only 5 years because their state credit was 5 years, or vice versa. Keep them separate in your mind and records. Each credit (federal, state) has its own carryover terms. Also, don’t try to claim your state credit on your federal return! (It has happened – people mistakenly put a state incentive somewhere on federal forms – there is no place for that; state credits only go on state returns.)
Selling or Leasing System Too Early (Recapture Risk): If you’re a business or even if you’re an individual who converts your home to a rental soon after (which might be considered a change of use), be mindful of the 5-year recapture period for business credits. A common error is not realizing that selling the asset or changing its use within 5 years triggers payback of part of the credit. If you plan to sell a solar-equipped rental property in 2 years, for instance, part of the credit used (and even carryforward potentially) will have to be returned. Plan asset sales with the 5-year window in mind to avoid this clawback.
Not Retaining Documentation: The IRS may never specifically ask about your carryforward, but they could audit the credit itself. Keep all your documentation from the installation: invoices, contracts, proof of payment, and any necessary certification (like the manufacturer’s certification for the property meeting credit criteria, if applicable). Also keep copies of all tax forms claiming the credit. If years later the IRS questions the original credit amount or whether the system was eligible, you’ll need to produce records. A mistake is discarding paperwork after the install year – hold onto it at least until the credit is fully used (and then some years after that per general audit timelines, say keep for 5-7 years after credit fully used).
Misunderstanding “placed in service” year: Sometimes people try to claim the credit in the wrong year – e.g., you paid a deposit in one year but the system wasn’t operational until the next year. The credit is claimable in the year the system is placed in service (operational), not necessarily when paid. If you claimed it too early and then had no carryforward show up when it should, you might have a problem. Ensure you claim in the correct tax year. If you straddle New Year’s, be careful to claim on the later year if that’s when permission to operate was given.
Relying on Inaccurate Advice: Unfortunately, not all tax preparers or solar salespeople are well-versed in these details. Some homeowners have been incorrectly told “you can only carry it forward 1 year” or “5 years” etc. That misinformation can cause panic or bad decisions (like thinking you must owe more tax quickly or you’ll lose it). Always double-check with authoritative sources or knowledgeable tax professionals. The mistake here is taking action (or losing sleep) based on bad info. By reading this guide, you’re arming yourself with accurate knowledge: you know homeowners have no fixed limit, and businesses have 20/22 years.

Avoiding these mistakes largely comes down to being informed and organized:

Follow the forms carefully.
Keep track year to year.
Consult a tax professional if you’re unsure, especially for complex cases.

With pitfalls addressed, let’s reinforce your understanding with a few concrete examples and Q&As. We’ll run through scenarios to illustrate how carryforwards work in practice, then wrap up with a quick FAQ to answer the most common questions.

Real-Life Examples: Using Solar Tax Credits Over Multiple Years

To solidify how carryforward works, let’s walk through a few typical scenarios. These examples will show year-by-year how unused credits carry over for different situations: a homeowner with low tax liability, a business leveraging depreciation, and a mixed-use property scenario.

Example 1: Homeowner with Low Tax Liability (Gradual Credit Use)

Situation: Jane is a retired homeowner who installed solar on her home in 2024 for $30,000. This gives her a federal tax credit of $9,000 (30% of $30k). However, her federal tax liability for 2024 is only $1,500 (she has modest taxable income from investments).

Carryforward process: Jane will use $1,500 of her $9,000 credit to bring her 2024 tax to zero. The remaining $7,500 carries forward. Each year, she’ll apply the credit up to her tax owed.

Tax Year	Federal Tax Owed (before credit)	Credit Used that Year	Credit Carried Forward at Year-End
2024 (installation)	$1,500	$1,500 used (of $9,000 credit)	$7,500 carried forward to 2025
2025	$1,600	$1,600 used (credit reduces tax to $0)	$5,900 carried to 2026
2026	$1,700	$1,700 used	$4,200 carryforward remaining
2027	$1,800	$1,800 used	$2,400 remaining
2028	$1,900	$1,900 used	$500 remaining
2029	$500	$500 used	$0 remaining (credit fully utilized)

Outcome: It took Jane until her 2029 tax return to fully use the $9,000 credit – 6 years. At no point did she lose any of it; it simply rolled over each year. Each year’s Form 5695 claimed the carryforward. By 2029, her credit balance is zero. She never paid federal tax in those years either, since each year’s small tax bill was wiped out by the credit.

Example 2: Business with Large Credit and MACRS Depreciation

Situation: GreenTech Co. is a business that installed a commercial solar system in 2025 costing $500,000. The federal ITC is $150,000 (30%). Thanks to 5-year MACRS depreciation and bonus depreciation, GreenTech has very low taxable income in 2025 – their tax liability is only $10,000 for that year.

Carryforward and carryback: GreenTech will use $10,000 of the credit to offset 2025 taxes to zero. They have $140,000 unused. They decide to carry back $20,000 of the credit to 2024 (since they paid taxes that year and can get a refund) and carry the remaining $120,000 forward.

Tax Year	Action and Credit Usage	Remaining Credit Carryforward
2025 (install year)	$10,000 used against 2025 taxes (now $0 tax). Elected to carry back $20,000 to 2024.	$120,000 carried forward to future years (22-year window starts from 2025).
Carryback to 2024	(Amended 2024 return, got $20,000 refund from IRS for taxes paid in 2024)	(carryback reduces the carryforward, which we did above)
2026	Business recovers, owes $50,000 in taxes. Uses $50,000 of carryforward credit to cut 2026 tax to $0.	$70,000 carryforward remains.
2027	Owes $40,000 tax. Uses $40,000 credit.	$30,000 remains.
2028	Owes $30,000 tax. Uses $30,000 credit – fully uses the remaining carryforward.	$0 remains (credit fully used by 2028).
2029+	Owes tax, but no credit left to use.	—

Outcome: GreenTech effectively utilized the $150k credit by 2028:

Immediately in 2025 for that year’s tax ($10k).
Got a refund for 2024 by carrying back $20k.
Used the rest in 2026-2028 as profits (and taxes) returned.
The 22-year available window wasn’t an issue; they used it within 3 years of carryforward. If GreenTech had stayed unprofitable longer, they still had until 2047 to use it, theoretically. This example shows how a business might strategically use carryback first, then carryforward.

Example 3: Mixed-Use Property – Personal Residence with Rental Unit

Situation: Alex owns a duplex, lives in one unit, rents out the other. Installs solar PV for $20,000 in 2023. He allocates 50% of the cost to his residence and 50% to the rental. So:

Residential credit = 30% of $10,000 = $3,000.
Business (rental) credit = 30% of $10,000 = $3,000.

Alex’s personal tax liability is $1,000 per year. His rental (passive) income tax liability is $800 per year (and assume passive income so credit limited to $800 usage per year there).

Carryforward usage:

Tax Year	Personal Credit (Home half) Usage	Business Credit (Rental half) Usage
2023 (install)	$1,000 used out of $3,000 (personal tax wiped out). Carryforward personal credit: $2,000.	$800 used out of $3,000 (rental passive tax wiped out). Carryforward business credit: $2,200 (subject to passive limit forward).
2024	$1,000 used (personal carryforward now $1,000 remains).	$800 used (business carryforward $1,400 remains).
2025	$1,000 used (personal credit now fully used, $0 remains).	$800 used (business carryforward $600 remains).
2026	(No personal credit left to use)	$600 used (business credit fully used this year).
2027+	No personal credit.	No business credit.

Outcome: By 2026, Alex has utilized both portions completely. The personal credit took until 2025 to finish (3 years of carryforward) given his $1k/year tax. The rental credit, limited by $800/year passive tax, took until 2026 to finish ($3k over four years). Both were within allowable time (personal unlimited, business well within 22 years). Alex had to file Form 5695 each year until 2025 for the personal portion, and Form 3800 with passive credit tracking each year until 2026 for the rental portion.

These examples mirror many real cases:

Retirees or low-income households often use up the credit over 5-10 years.
Businesses with large systems may carry forward a lot but usually start using it within a few years as profits resume.
Mixed-use requires splitting but you still eventually get full benefit on both parts.

The key across examples is consistent annual claiming and tracking. As long as you follow through each year, the credits serve their purpose: reducing your tax bill, whether immediately or gradually.

With these scenarios under our belt, let’s finish with a concise FAQ to address the most common quick questions people have about carrying forward solar tax credits.

FAQ: Frequently Asked Questions

Q: Is there a time limit on using the federal solar tax credit?
A: Homeowners have no fixed time limit – you carry it forward until it’s gone. Businesses have up to 20 years (22 years under new rules) to use unused solar credits.

Q: Will I lose my solar tax credit if I don’t use it this year?
A: No, you won’t lose it. Any unused amount simply rolls over to next year (for future use) as long as you file for it. It stays available until fully used (subject to business 20/22-year limit).

Q: Do I get a refund check for unused solar credit?
A: No. The solar credit is nonrefundable. You won’t receive a refund for the unused portion in that year. Instead, the excess is carried forward to offset future tax bills.

Q: How do I claim a carryforward on my tax return?
A: Individuals: Fill out Form 5695 each year – it has a line for prior year’s unused credit to carry in. Businesses: Use Form 3800 to report carryforwards of general business credits. Always include these forms so the IRS knows you’re using carried credit.

Q: What if I still have credit left after 20+ years (business)?
A: In theory, a business credit unused after 22 years would expire. In practice, this is rare. Plan ahead if a credit is nearing expiration (e.g., try to use it or consider transferring if possible under current law).

Q: Can I carry forward the credit if I lease solar panels?
A: No, if you lease, you typically cannot claim the credit in the first place (the leasing company would). Carryforward only applies if you own the system and have an unused credit you earned.

Q: Does selling my house or solar system affect my credit carryforward?
A: For homeowners, once you’ve earned the credit, you keep the carryforward even if you sell the house. There’s no recapture for personal credits. For businesses, selling the solar-equipped property within 5 years triggers partial recapture (payback) of the credit, which could effectively negate remaining carryforward.

Q: Can I split the solar credit with someone else or transfer it?
A: Not for personal credits – it stays with the taxpayer who paid for and owns the system. Businesses (in 2023+) can transfer credits to an unrelated taxpayer for cash, but that’s effectively selling the credit rather than carrying it forward on your return.

Q: Do state solar credits have the same carryforward rules?
A: No, state credits vary. Many have a 5-year carryforward limit (some 3, some 10). Always check your state’s specific rules – they are separate from federal rules.

Q: If I have zero tax liability for several years, can I keep carrying the credit forward?
A: Yes. If you owe no tax for, say, three years in a row, your credit simply carries forward each year intact. You then use it in the first year you do owe taxes. Just be sure to file for the carryforward each year.

Q: Does the solar tax credit carryforward expire when the credit program ends (in 2035)?
A: No. The ability to use previously earned credit continues even after the credit for new installations expires. If you earned a credit in 2034 and still have some left in 2035 or beyond, you can carry it forward until it’s used (per the law in effect now).