Is Cost Segregation Going Away? (w/Examples) + FAQs

No, cost segregation is not going away. In fact, the strategy just got a major boost. On July 4, 2025, President Trump signed the One Big Beautiful Bill (P.L. 119-21) into law, permanently restoring 100% bonus depreciation for qualified property acquired and placed in service after January 19, 2025 — eliminating the phase-out that once threatened to make cost segregation far less powerful.

According to industry estimates, 90% of qualifying properties never use cost segregation — meaning billions in unnecessary taxes are paid each year. If you own real estate and are not using this strategy, you are likely handing the IRS money that belongs in your pocket.

Here is what you will learn in this article:

💡 Why cost segregation is stronger than ever — and the exact law that made it permanent

🏗️ How cost segregation actually works — broken down in plain language with real numbers

📊 Three real-world scenarios showing the tax impact across different property types

⚠️ The most expensive mistakes investors make — and the IRS audit risks you need to know

🔁 How lookback studies work — so you can claim years of missed deductions you never knew about

What Is Cost Segregation?

Cost segregation is an IRS-approved tax strategy that lets real estate owners accelerate depreciation deductions by breaking a property into individual components — each with its own shorter depreciation life. Instead of depreciating the entire building over 27.5 years (residential) or 39 years (commercial), a cost segregation study identifies components like flooring, electrical wiring, specialty lighting, plumbing fixtures, and parking lots. These components get reclassified into 5-year, 7-year, or 15-year depreciation schedules, allowing massive deductions in the early years of ownership.

The strategy is grounded in IRS Revenue Procedure 87-56 and supported by the IRS’s own Cost Segregation Audit Techniques Guide, which instructs its examiners on how to review these studies. This is not a gray area or aggressive loophole — it is a recognized, codified method of depreciation accounting. The IRS does not discourage cost segregation; it regulates how it must be done correctly.

When you pair a cost segregation study with bonus depreciation under Section 168(k) of the Internal Revenue Code, you can write off 100% of the reclassified components in the year the property is placed in service. That is the real power of this strategy.

The Bonus Depreciation Timeline

To understand why people worried about cost segregation going away, you need to understand what almost happened to bonus depreciation. The Tax Cuts and Jobs Act (TCJA) of 2017 set bonus depreciation at 100% through 2022 — then scheduled it to shrink by 20% each year until it disappeared entirely by 2027.

Here is how the phase-down played out before the new law intervened:

Year	Bonus Depreciation Rate
2022	100%
2023	80%
2024	60%
2025 (pre-Jan 20)	40%
2025 (post-Jan 19)	100% (OBBBA)
2026 and beyond	100% (permanent)

The One Big Beautiful Bill permanently stopped this decline and reset the rate to 100% for qualifying property. Cost segregation was never going away on its own — it is a separate accounting method with no sunset date. But bonus depreciation was going away, which would have reduced cost segregation’s first-year tax punch significantly. That threat is now off the table.

How a Cost Segregation Study Works

A cost segregation study is performed by a team that typically includes both an engineer and a tax professional. The engineer physically inspects the property, reviews architectural plans, construction invoices, and contractor records, and then assigns each component of the building to an IRS asset class. That classification determines the depreciation life of each component.

The IRS Audit Techniques Guide instructs its examiners to look for studies that categorize assets, provide legal citations supporting each classification, and reconcile allocated costs with actual construction costs. A quality study also includes photo documentation, detailed technical narratives, and a methodology traceable back to actual cost records. Without this level of rigor, the study becomes difficult to defend in an audit.

The most common components reclassified during a study include:

·         5-year property: Carpeting, specialty electrical for equipment, decorative millwork, certain plumbing fixtures

·         7-year property: Office furniture, equipment, certain fixtures

·         15-year property: Parking lots, sidewalks, landscaping, fencing, site lighting, Qualified Improvement Property (QIP)

·         27.5 / 39-year property: The remaining structural shell of the building

Qualified Improvement Property (QIP)

One of the most underused aspects of cost segregation is its interaction with Qualified Improvement Property (QIP). QIP refers to interior improvements made to a non-residential building after it was originally placed in service. Examples include renovating a retail store’s interior, upgrading an office suite’s HVAC system, or redesigning a restaurant’s layout.

Under current law, QIP enjoys a 15-year recovery period instead of the standard 39 years for commercial property — and it qualifies for 100% bonus depreciation. A cost segregation study is the most reliable tool for correctly identifying and separating QIP items from other structural components. Without the study, many of these components get lumped into the 39-year category by default, and those deductions are permanently delayed. The consequence: you overpay your taxes every year you own that property.

Three Real-World Scenarios

Scenario 1: The Residential Rental Investor

Maria buys a $1.2 million single-family rental home (land valued at $200,000, so the depreciable basis is $1,000,000). Without cost segregation, she depreciates the entire $1,000,000 over 27.5 years — roughly $36,363 per year.

Without Cost Segregation	With Cost Segregation
$36,363 annual depreciation	$300,000+ deducted in Year 1 via bonus depreciation
Taxes reduced modestly each year	At 37% tax rate: ~$111,000 in first-year tax savings
No upfront cash flow benefit	Significant cash flow freed in Year 1
Compounded missed savings over 27.5 years	Remaining basis depreciated over standard schedule

A cost segregation study on her property would likely reclassify 20–30% of the building’s value into 5-year and 15-year components. At 100% bonus depreciation, that entire reclassified amount becomes deductible immediately. The study itself typically costs $3,000–$8,000 for a property this size — a fraction of the tax benefit.

Scenario 2: The Commercial Office Building

David purchases a $4 million office building ($600,000 land, $3.4 million depreciable basis). Without a study, he depreciates $3.4 million over 39 years — about $87,000 per year.

Without Cost Segregation	With Cost Segregation
$87,179 in Year 1 deduction	$800,000+ reclassified to 5–15 year property
Majority of deductions delayed decades	$800,000 fully deducted in Year 1 at 100% bonus
Tax savings spread too thin to meaningfully improve ROI	At 37% rate: ~$296,000 in immediate tax savings
No impact on capital reinvestment	Capital freed for next acquisition or property upgrades

Under the One Big Beautiful Bill, the entire reclassified portion can be written off in Year 1. What would have taken decades to deduct now happens on a single tax return.

Scenario 3: The Restaurant Renovation

Lisa owns a commercial building and spends $900,000 renovating it into a restaurant space. The interior buildout includes specialty electrical, custom millwork, exhaust systems, plumbing for kitchen equipment, and decorative flooring. Without a cost segregation study, the entire $900,000 gets depreciated over 39 years as a structural improvement.

Without Cost Segregation	With Cost Segregation + QIP
$23,076 deducted in Year 1	Up to $600,000+ reclassified as 5–15 year / QIP
Tax bill unchanged for years	$600,000 written off in Year 1 using bonus depreciation
ROI on renovation severely delayed in tax terms	Restaurant cash flow dramatically improved from Day 1
IRS receives taxes owed now rather than later	Tax liability deferred or eliminated for multiple years

The specialty kitchen wiring, exhaust hoods, plumbing for food service equipment, and decorative finishes all qualify as Section 1245 personal property — reclassifiable in a cost segregation study. Lisa’s renovation is a textbook QIP opportunity.

Passive Activity Loss Rules: The Hidden Wall

Here is what many real estate investors do not realize: generating a large depreciation deduction through cost segregation does not automatically mean you can use it to offset your W-2 salary or business income. IRC Section 469 classifies rental income as passive, which means losses from rental properties generally can only offset other passive income — not active income like wages.

There are two major exceptions that allow you to use these losses against ordinary income:

1.   Real Estate Professional Status — If you materially participate in real property trades or businesses for more than 750 hours per year, and that time exceeds your time in any other profession, your rental activities are no longer passive. You can use depreciation losses to offset any income.

2.  Short-Term Rental Loophole — If your average guest stay is 7 days or fewer and you materially participate in the rental, the property is treated as a non-passive activity under IRS rules, meaning losses flow directly to your tax return.

If neither exception applies, your cost segregation deductions may pile up as suspended passive losses, carried forward until you either generate passive income or sell the property. The strategy still works — it just works differently depending on your tax situation. This is why consulting a CPA before ordering a study is critical, not optional.

The Lookback Study: Catching Up on Missed Years

If you purchased or renovated a property years ago and never did a cost segregation study, you have not necessarily missed your window. A lookback cost segregation study allows you to catch up on all the accelerated depreciation you never claimed — and you can do it on your current tax return using Form 3115, Application for Change in Accounting Method.

Here is how it works: the study calculates the difference between the depreciation you actually claimed and the depreciation you could have claimed under cost segregation since the property was placed in service. That difference becomes what is called a Section 481(a) adjustment — a lump-sum catch-up deduction taken entirely in the current tax year. You do not have to amend prior returns. You claim everything at once.

For example, if Tom bought a $2 million apartment building 6 years ago and never did a study, his lookback might reveal $180,000 in deductions he never took. He files Form 3115, takes the $180,000 481(a) adjustment this year, and reduces his current-year tax bill significantly. The retroactive approach of amending prior returns is also available but is more complex — it makes sense when a prior high-income year would have generated a larger refund.

Depreciation Recapture: The Real Cost of Selling

Cost segregation is a tax deferral strategy — not a permanent tax elimination. When you sell the property at a gain, the IRS uses depreciation recapture to claw back some of those earlier deductions and tax them at higher rates.

Here is how recapture breaks down under current law:

·         Section 1250 property (structural components): Recaptured at a maximum rate of 25%

·         Section 1245 property (personal property you reclassified): Recaptured at your ordinary income rate — up to 37%

The critical insight here is that recapture is not a reason to avoid cost segregation — it is a reason to plan for it. You took those deductions when your tax rate may have been 37%. When you sell, you pay recapture at a capped 25% on real property. That is still a net arbitrage gain. And if you hold the property for at least 3–5 years, many of the 5-year personal property components will have been fully depreciated and may generate no recapture at all upon sale, because their adjusted basis is already zero.

You can also avoid recapture entirely by executing a Section 1031 Like-Kind Exchange, rolling the proceeds into a new qualifying property and deferring both capital gains and recapture taxes indefinitely.

Mistakes to Avoid

Many investors make costly errors when approaching cost segregation. Each one has a direct negative consequence:

·         Using a non-engineer provider: Tax professionals without engineering credentials often produce studies that cannot withstand IRS scrutiny. The IRS gives more credibility to engineering-based methodology. A poorly documented study can be partially or fully disallowed on audit, triggering back taxes, interest, and penalties.

·         Ignoring passive activity loss rules: Taking a $400,000 cost segregation deduction when all your income is W-2 wages and you do not qualify for real estate professional status means those losses sit suspended and unused. You pay a CPA, order a study, and see zero immediate tax benefit. Always model your tax position before ordering the study.

·         Skipping a study on renovation projects: Many investors only consider cost segregation for new purchases, missing the fact that QIP and renovation costs are prime candidates for reclassification. Interior improvements to commercial buildings go straight to 39 years by default — a study unlocks the 15-year QIP treatment and bonus depreciation.

·         Not considering recapture at disposition: Selling a property without accounting for Section 1245 recapture can result in a surprise tax bill at ordinary income rates. Plan your exit strategy — 1031 exchanges, installment sales, and opportunity zone investments can all manage this exposure.

·         Waiting until tax season: Cost segregation studies take time to complete correctly. Ordering a study in March for a property placed in service in January of the prior year may limit your options. Engage your team in the same year you acquire or substantially renovate the property.

·         Applying cost segregation to low-value properties: There is no IRS-mandated minimum for cost segregation, but practicality matters. If the study costs $5,000 and only generates $8,000 in total tax savings, the net benefit is minimal. The strategy becomes highly compelling on properties with a depreciable basis above $750,000.

·         DIY or software-only studies: IRS examiners evaluate the rigor of the methodology used to prepare a study. A spreadsheet-based or software-generated study without site inspection, photo documentation, and engineering analysis carries a materially higher audit risk.

Do’s and Don’ts of Cost Segregation

Do’s:

·         Do hire a qualified engineering firm. The IRS’s own Audit Techniques Guide validates engineering-based methodology as the gold standard. Your study must be able to withstand examination.

·         Do model your passive activity situation first. Know whether you qualify as a real estate professional or can use the short-term rental exception before you spend money on a study.

·         Do consider lookback studies on older properties. Properties placed in service as far back as 15–20 years ago can still benefit from a lookback using Form 3115. Do not assume you missed your chance.

·         Do coordinate with QIP rules. Any time you renovate a commercial building after it was originally placed in service, ask whether those costs qualify as QIP. The 15-year life and bonus depreciation eligibility make a significant difference.

·         Do plan for recapture. Know your exit strategy before you enter. A 1031 exchange, installment sale, or long hold period can meaningfully reduce or defer recapture taxes.

Don’ts:

·         Don’t assume cost segregation only applies at purchase. Renovations, expansions, and even tenant improvements can trigger a new study opportunity.

·         Don’t ignore the acquisition date threshold under the OBBBA. For property acquired via a written binding contract before January 20, 2025, the old 40% transitional bonus depreciation rate applies — not 100%. Getting this wrong understates or overstates your deduction.

·         Don’t use cost segregation without a plan to use the losses. Passive loss suspension is real. If your deductions get trapped, you have deferred a tax benefit you may not access for years.

·         Don’t skip documentation. The IRS looks for photo evidence, engineering narratives, and reconciled cost data. A study without these elements is a study that gets challenged.

·         Don’t sell without talking to your CPA first. Recapture on Section 1245 property at ordinary income rates is a real tax event that needs advance planning, not a conversation you have after the closing.

Pros and Cons of Cost Segregation

Pros:

·         Massive first-year deductions. Reclassifying 20–40% of a building’s value into 5–15 year property — combined with 100% bonus depreciation — can generate six-figure write-offs in Year 1 on a $1 million+ property.

·         Improved cash flow. Paying less in taxes today means more capital available for reinvestment, debt service, or property upgrades.

·         Permanent strategy under current law. With the OBBBA making 100% bonus depreciation permanent, there is no legislative sunset looming over the strategy.

·         Lookback studies create immediate value. Properties owned for years that never had a study can generate a substantial lump-sum deduction on the very next tax return via Form 3115.

·         Tax arbitrage on recapture. You take deductions at marginal rates (up to 37%) and pay recapture on real property at a capped rate of 25% — a built-in tax rate advantage.

Cons:

·         Recapture on sale. Accelerated depreciation on personal property components is subject to Section 1245 recapture at ordinary income rates when you sell, which can be significant if the property appreciated.

·         Study cost. A credible, engineering-based study typically costs $5,000–$15,000 depending on property size and complexity. This cost must be weighed against projected savings.

·         Passive activity limitations. Without real estate professional status or the short-term rental exception, large depreciation deductions may be suspended, reducing the immediate tax benefit.

·         IRS audit attention. Aggressive or improperly documented cost segregation studies are an IRS audit trigger. A poorly prepared study puts the entire depreciation position at risk.

·         Not ideal for short holds. If you plan to sell within 2–3 years, recapture taxes may partially offset the benefit of accelerated depreciation, particularly on Section 1245 components that have not yet fully depreciated.

Key Entities You Need to Know

The IRS issues the governing rules through the Internal Revenue Code (primarily Sections 168, 179, 1245, and 1250) and maintains the Cost Segregation Audit Techniques Guide, which outlines exactly what a compliant study looks like from the examiner’s perspective.

Section 168(k) is the specific code provision governing bonus depreciation. It determines which property qualifies, at what percentage, and under what timing conditions. The OBBBA modified Section 168(k) to make 100% bonus depreciation permanent starting January 20, 2025.

Section 179 is a separate expensing provision that allows businesses to immediately deduct the cost of qualifying property, with a 2025 cap raised by the OBBBA. It differs from bonus depreciation in that it cannot create a loss — it is capped at your taxable income. The two provisions can interact, and your CPA must understand the optimal sequencing.

IRS Notice 2026-11 provides interim guidance on how bonus depreciation rules under the OBBBA apply to property placed in service during the transitional period of 2025, specifically clarifying that the 40% rate applies to property acquired via binding contract before January 20, 2025, and placed in service in 2025.

Form 3115 is the IRS form used to change your accounting method — the vehicle through which a lookback cost segregation study delivers its catch-up deduction on the current return via a Section 481(a) adjustment.

Who Qualifies for Cost Segregation?

You likely qualify if all of the following are true:

·         You own the property for tax purposes (or own the improvements)

·         The property is used for business or rental purposes

·         The depreciable basis is generally above $500,000–$750,000 for a cost-effective study

·         The property was purchased, newly constructed, renovated, or expanded

You do not need to be a corporation or a large commercial developer. Individual real estate investors, LLCs, S-corps, and partnerships all use cost segregation. There is no IRS-mandated minimum value — but the economics break down for low-value properties when the cost of the study approaches the value of the savings.

Foreign-owned property does not qualify. The property must be placed in service within the United States to be eligible for bonus depreciation under Section 168(k).

FAQs

Is cost segregation going away?
No. Cost segregation is a permanent accounting method. Bonus depreciation — which amplifies its value — was restored to 100% permanently by the One Big Beautiful Bill signed July 4, 2025.

Does cost segregation work without bonus depreciation?
Yes. Even without bonus depreciation, cost segregation accelerates deductions into 5, 7, and 15-year schedules instead of 27.5 or 39 years, generating significantly higher early-year write-offs.

Can I do a cost segregation study on a property I already own?
Yes. A lookback study via Form 3115 lets you catch up on all missed depreciation in the current tax year using a Section 481(a) adjustment — no amended returns required.

Will a cost segregation study trigger an IRS audit?
No, not automatically. Properly documented, engineering-based studies are recognized by the IRS. Poorly executed or unsupported studies are what draw scrutiny and risk disallowance.

Does cost segregation apply to residential rental properties?
Yes. Single-family rentals, multifamily apartments, short-term rentals, and mixed-use properties all qualify, provided they are held for business or rental use.

Do I have to pay back the tax savings when I sell?
Yes, partially. Depreciation recapture applies — Section 1245 property at ordinary income rates, Section 1250 at a capped 25% rate. A 1031 exchange can defer this tax.

Is cost segregation only for new construction?
No. Existing properties, renovations, and expansions all qualify. Any building component placed in service — even years ago — can potentially be reclassified through a lookback study.

Can a CPA perform a cost segregation study without an engineer?
Yes, technically, but it is inadvisable. The IRS gives significantly more credibility to engineering-based methodology, and non-engineering studies carry higher audit risk and weaker defensibility.

Does Section 179 replace cost segregation?
No. Section 179 cannot generate a loss and is capped at taxable income. Cost segregation paired with bonus depreciation has no such limitation and is typically the more powerful tool for real estate.

Does cost segregation apply to land improvements?
Yes. Parking lots, sidewalks, fencing, landscaping, and exterior lighting are classified as 15-year property and are eligible for bonus depreciation under a properly conducted study.

Can I use cost segregation losses against my W-2 income?
No, unless you qualify as a real estate professional under IRC Section 469 or meet the short-term rental material participation exception. Otherwise, losses are suspended as passive.Is cost segregation legal?
Yes. It is explicitly recognized and governed by IRS Code Section 168, IRS Revenue Procedure 87-56, and the IRS’s own Audit Techniques Guide. It is a mainstream, IRS-sanctioned strategy used by investors nationwide.