Can You Convert Just Part of Your IRA to a Roth? (w/Examples) + FAQs

This article reflects federal rules as of June 2026 and covers tax years 2025 and 2026. Tax law changes — confirm current figures with IRS.gov before you file.

Quick Answer

Yes. For tax year 2025, you can convert any part of a traditional IRA to a Roth IRA — $5,000, $50,000, or any amount you choose. There is no minimum, no maximum, and no annual limit on conversions. You pay ordinary income tax only on the pre-tax amount you actually convert that year.

A partial Roth conversion lets you move money on your schedule instead of all at once, so you control how much extra income — and tax — you trigger in a single year. This matters because converting your whole IRA in one shot can push you into a higher bracket, raise your Medicare premiums two years later, and hand the IRS a tax bill you did not need to pay so soon.

The strategy is more popular than ever. Fidelity reported record Roth conversion activity in recent years as savers race to lock in today’s historically low brackets. Here is what you will learn:

• 💵 How partial conversions work and why there is no legal cap on the amount
• 🧮 The “bracket-filling” math, with real dollar examples you can copy
• ⚠️ The pro-rata rule that can make your “tax-free” backdoor Roth taxable
• 🏥 How conversions can spike your Medicare (IRMAA) premiums two years later
• 📋 Exactly which form to file, when to convert, and the December 31 deadline

What a Partial Roth Conversion Actually Is

A Roth conversion moves money from a pre-tax retirement account, like a traditional IRA, into a Roth IRA. A partial conversion simply means you move only a slice, not the whole balance. The IRS treats the converted pre-tax amount as ordinary income in the year you convert it, and you pay tax at your regular rate.

There is no rule forcing an all-or-nothing decision. You can convert $10,000 this year, $25,000 next year, and nothing the year after. This flexibility is the entire point: you decide how much taxable income to create each year, which gives you direct control over your tax bracket.

The money keeps growing the whole time. Once it lands in the Roth, future growth and qualified withdrawals are tax-free, and Roth IRAs have no required minimum distributions during the original owner’s lifetime. That is why people accept a tax bill now — they are buying decades of tax-free growth and removing future forced withdrawals.

Anyone can do it, regardless of income. Congress removed the income limit on conversions back in 2010, so a high earner who cannot contribute to a Roth directly can still convert into one. The IRS confirms there is no income ceiling on conversions.

Why Convert Only Part Instead of the Whole IRA

The core reason is bracket control. Federal income tax is tiered, so the more income you stack in one year, the higher the rate on the top slice. A partial conversion lets you add just enough income to “fill up” your current bracket without spilling into the next one.

Consequence of ignoring this: a retiree with a $400,000 IRA who converts it all in one year could push a large chunk of that money into the 32% or 35% bracket for tax year 2025, when a series of smaller conversions might have stayed at 12% or 22%. The difference can be tens of thousands of dollars.

A real-world example shows the contrast. Maria, age 62 and retired, has $300,000 in a traditional IRA. If she converts it all in 2025, much of it is taxed at 24% and above. Instead, she converts $40,000 a year for several years, keeping each conversion inside the 22% bracket — and saves a large amount of lifetime tax.

A common misconception is that you must “use up” the conversion by a deadline or lose it. Not true. Unconverted money simply stays in the traditional IRA, and you decide again next year.

What to do about it: estimate your taxable income for the year, find the top of your current bracket, and convert only up to that ceiling. Run the number before December 31, because once the calendar year ends, that year’s conversion window closes.

The Bracket-Filling Strategy (w/Worked Example)

Bracket-filling means converting exactly enough to reach the top of your current tax bracket, but not a dollar more. The 2025 federal brackets for married filing jointly tax income from $23,851 to $96,950 at 12%, and from $96,951 to $206,700 at 22%.

Here is the math, step by step, for a married couple in tax year 2025:

1. Estimate taxable income before any conversion: $70,000.
2. Find the top of the 22% bracket: $206,700.
3. Subtract to find your conversion room: $206,700 − $70,000 = $136,700.
4. Convert up to $136,700 and every converted dollar stays at 22% or lower.
5. The tax on that conversion slice is roughly $136,700 × 22% = $30,074 at the margin.

If this couple instead converted $250,000 in one year, the amount above $206,700 would jump into the 24% bracket, and a bigger conversion would reach 32%. By stopping at the bracket line, they avoid those higher rates entirely.

A common mistake here is forgetting that the conversion adds to your other income. Wages, pensions, interest, Social Security, and capital gains all count first. The conversion sits on top, so always start from your projected total income, not zero.

What to do about it: pull your most recent tax return, project this year’s income, and convert only the gap up to your target bracket ceiling. Many people aim for the top of the 22% or 24% bracket during low-income early-retirement years before Social Security and RMDs begin.

The Pro-Rata Rule: The Trap That Catches Backdoor Roths

The pro-rata rule decides how much of your conversion is taxable when your IRAs hold both pre-tax money and after-tax (already-taxed) money. You cannot simply convert “only the after-tax part.” The IRS requires you to treat all your traditional, SEP, and SIMPLE IRAs as one combined pot.

Here is how the math works. You divide your total after-tax basis by the total value of all your traditional IRAs. That percentage is the tax-free share of any conversion; the rest is taxable.

A worked example makes it clear. David has $7,000 of after-tax (non-deductible) contributions and $93,000 of pre-tax money, for $100,000 total. His after-tax share is $7,000 ÷ $100,000 = 7%. If he converts $7,000 hoping it is tax-free, only 7% ($490) is tax-free and 93% ($6,510) is taxable.

The consequence of missing this rule is a surprise tax bill. Many high earners attempt a “backdoor Roth” — contribute after-tax, then convert — and assume it costs nothing. If they hold any other pre-tax IRA money, most of the conversion becomes taxable, as Northern Trust explains.

A common misconception is that you can dodge the rule by using a separate IRA. You cannot, because the IRS aggregates every traditional IRA you own on December 31. The fix many people use is rolling pre-tax IRA money into a current 401(k), which is excluded from the pro-rata calculation, as this guide describes.

What to do about it: file Form 8606 every year you make after-tax contributions or conversions, so you track your basis and prove which dollars were already taxed.

Which Situation Applies to You?

The right conversion size depends on your stage of life and income. Use this quick guide to find the part of the strategy that fits you.

• Early retiree, low income, before Social Security and RMDs: This is the prime window. Convert up to the top of the 22% or 24% bracket each year while your income is low.
• High earner still working: Watch the pro-rata rule before any backdoor Roth, and beware adding conversion income on top of a high salary.
• Near RMD age (73 or older): Convert after taking your required minimum distribution, and use conversions to shrink future RMDs.
• On Medicare or within two years of it: Track the IRMAA thresholds, because conversion income raises premiums two years later.
• You hold after-tax basis in any IRA: The pro-rata rule applies — calculate your taxable share before converting.

The Medicare (IRMAA) Surcharge Most People Miss

A Roth conversion raises your modified adjusted gross income (MAGI), and Medicare uses MAGI from two years ago to set your Part B and Part D premiums. This is the Income-Related Monthly Adjustment Amount, or IRMAA. A conversion in 2025 can raise your 2027 premiums.

For 2025, a married couple with MAGI at or below $212,000 pays the base Part B premium of $185.00 per person, per the CMS premium release. Cross $212,000 by even one dollar and the premium jumps to $259.00 each — a “cliff,” not a gradual slope.

The consequence is steep. A couple that converts just enough to tip over a threshold can pay hundreds or thousands more in annual Medicare premiums for a full year. Because it is a cliff, $1 of extra conversion can cost over $1,700 a year for the pair.

A worked example: Robert and Susan, both on Medicare, have MAGI of $205,000 in 2025. They have $7,000 of conversion room before the $212,000 IRMAA cliff. If they convert $7,000, they stay at the base premium; converting $20,000 pushes them over and raises both their premiums.

What to do about it: if you are 63 or older, check the IRMAA brackets before converting and leave a safety cushion below the next threshold.

Three Common Scenarios at a Glance

These tables show how the same decision plays out differently depending on the goal. Each compares the conversion move with its result.

Scenario 1 — Early retiree filling the 22% bracket (2025)

Conversion Move	Tax Result
Convert $40,000 with $60,000 other income	Stays in 22% bracket, ~$8,800 tax at the margin
Convert $200,000 in one year	Spills into 24% bracket, far higher total tax

Scenario 2 — Backdoor Roth with existing pre-tax IRA (2025)

Conversion Move	Tax Result
Convert $7,000 after-tax, no other IRA	100% tax-free if no pre-tax balance exists
Convert $7,000 with $93,000 pre-tax IRA	Pro-rata rule makes 93% ($6,510) taxable

Scenario 3 — Couple near a Medicare IRMAA cliff (2025)

Conversion Move	Premium Result
Convert up to $212,000 MAGI	Base Part B premium of $185.00 each in 2027
Convert past $212,000 MAGI	Premium jumps to $259.00 each — a full-year cost

Three Named Examples in Action

Example 1 — Maria, the multi-year converter. Maria, 62, retired with a $300,000 traditional IRA and only $20,000 of other income in tax year 2025. She converts $76,000, filling her single-filer 22% bracket up to roughly $103,350, and repeats yearly. By age 70 she has shifted most of her IRA to a Roth at low rates and cut her future RMDs sharply.

Example 2 — David, the backdoor surprise. David, a 45-year-old high earner, contributes $7,000 after-tax and converts it, expecting no tax. Because he holds a $93,000 rollover IRA, the pro-rata rule taxes 93% of the conversion. He fixes it by rolling the $93,000 into his employer 401(k), then future backdoor Roths convert cleanly.

Example 3 — Robert and Susan, the IRMAA savers. This married couple, both 67 and on Medicare, have $205,000 MAGI in 2025. They convert exactly $7,000 to stay under the $212,000 IRMAA cliff, keeping their 2027 Part B premium at the base $185.00 each instead of triggering a year of higher charges.

How to Do a Partial Conversion: Step by Step

Converting is simpler than the tax planning around it. Most providers complete the actual transfer in minutes online, but the timing and paperwork decide your tax outcome.

1. Confirm you have a Roth IRA open at the same or another custodian. If not, open one first — it takes a few minutes.
2. Decide the dollar amount using your bracket and IRMAA limits before you click convert.
3. Request the conversion from your custodian, specifying the exact amount. You can convert cash or move shares “in kind.”
4. Decide on tax withholding. It is usually better to pay the conversion tax from a separate taxable account, not from the IRA, so 100% of the converted money keeps growing.
5. Make estimated tax payments if the conversion creates a large bill, to avoid an underpayment penalty.
6. File Form 8606 with your tax return to report the conversion and any basis. Your custodian will send a Form 1099-R, and the Roth custodian issues Form 5498.

The hard deadline is December 31 of the tax year. Unlike IRA contributions, which you can make until the April filing deadline, a conversion counts in the year the money actually moves, as Advanta IRA notes. Miss December 31 and the conversion belongs to the next tax year.

The Five-Year Rule on Converted Money

Each conversion starts its own five-year clock. If you are under 59½ and withdraw converted principal within five years, you may owe a 10% penalty on that amount, even though you already paid income tax on it. The IRS details this in Publication 590-B.

The consequence catches early retirees who convert and then tap the money too soon. A separate five-year clock runs for each conversion year, so a 2025 conversion and a 2026 conversion have different deadlines.

What to do about it: if you are under 59½, plan to leave converted dollars untouched for at least five years, and keep records of each conversion date so you know when each clock ends.

Mistakes to Avoid

• Converting your whole IRA in one year. This can push top dollars into the 32% or 35% bracket and waste years of low-rate room.
• Ignoring the pro-rata rule. Assuming a backdoor Roth is free when you hold pre-tax IRA money leads to an unexpected tax bill on most of the conversion.
• Forgetting IRMAA. Crossing a Medicare income cliff raises Part B and Part D premiums two years later, sometimes by thousands.
• Paying the tax from the IRA itself. This shrinks the amount that grows tax-free and may trigger an early-withdrawal penalty on the withholding.
• Missing the December 31 deadline. A conversion counts in the year the money moves, not when you file, so late means next year.
• Skipping Form 8606. Failing to file it means you may pay tax twice on after-tax basis and face a $50 penalty for the missing form.
• Converting right before a big RMD year without taking the RMD first. You must take your RMD before converting once you reach RMD age.

Do’s and Don’ts

Do’s – Do project your full-year income first, because the conversion stacks on top of everything else and decides your bracket. – Do convert during low-income years, such as early retirement, when rates are lowest and conversion room is widest. – Do pay the tax from outside the IRA, so every converted dollar keeps compounding tax-free. – Do file Form 8606 every year you have basis, to avoid being taxed twice on after-tax money. – Do check IRMAA and Social Security taxation thresholds before converting if you are 63 or older.

Don’ts – Don’t convert blindly to a round number, because the right amount depends on your bracket ceiling, not on convenience. – Don’t forget the pro-rata aggregation, since all traditional IRAs count as one for the calculation. – Don’t withdraw converted funds within five years if you are under 59½, to avoid the 10% penalty. – Don’t wait until late December to start, because processing and tax estimates take time before the deadline. – Don’t skip a CPA for large conversions, since a wrong move on six-figure conversions is expensive to undo.

Pros and Cons of Partial Roth Conversions

Pros – Tax-free growth and withdrawals, because qualified Roth distributions are never taxed again. – No lifetime RMDs, since Roth IRAs are exempt during the original owner’s life, lowering future forced income. – Bracket control, because you choose the conversion size and keep income inside a target bracket. – Tax diversification, giving you both taxable and tax-free buckets to draw from in retirement. – Estate benefit, because heirs inherit Roth dollars income-tax-free.

Cons – An upfront tax bill, since you owe ordinary income tax on the converted pre-tax amount now. – Possible IRMAA spikes, because higher MAGI raises Medicare premiums two years later. – The five-year penalty risk, for those under 59½ who withdraw too soon. – No do-overs, because conversions can no longer be reversed (recharacterized) after 2017. – Pro-rata complications, when after-tax and pre-tax IRA dollars are mixed.

Federal vs. State Treatment

Start with federal law: the conversion is fully taxable as ordinary income at the federal level for the pre-tax amount converted. Then ask the separate question — does my state tax it too?

Most states with an income tax follow the federal rule and tax the conversion as income in the year you convert. So a conversion can create both a federal and a state tax bill in the same year.

State Type	Conversion Tax Treatment
No-income-tax states (e.g., Florida, Texas, Tennessee)	No state tax on the conversion at all
States with income tax (e.g., California, New York)	Generally taxed as ordinary income, like federal

Some retirees deliberately convert after moving to a no-income-tax state to avoid the state bill entirely. Because state conformity varies, confirm your specific state’s rule with your state department of revenue before converting a large amount.

RMDs and the Conversion Order Rule

Required minimum distributions change the rules once you reach RMD age. Under SECURE 2.0, the RMD age is 73 for people born from 1951 to 1959 and 75 for those born in 1960 or later.

You cannot convert your RMD. In any year you owe an RMD, you must take that distribution first, and only money above the RMD can be converted. Converting an RMD by mistake creates an excess contribution problem in the Roth.

The upside is that converting before RMDs begin shrinks the traditional IRA balance, which lowers every future RMD and the taxes on them. This is why the years between retirement and age 73 are the most valuable conversion window for many people.

What to Do Next

1. Project your 2025 taxable income from all sources before adding any conversion.
2. Pick your target bracket ceiling using the 2025 IRS brackets, and subtract your income to find your conversion room.
3. Check the IRMAA thresholds if you are 63 or older, leaving a cushion below the next cliff.
4. Calculate your pro-rata share with Form 8606 if you hold any after-tax basis.
5. Set aside cash outside the IRA to pay the resulting tax, and arrange estimated payments if needed.
6. Complete the conversion before December 31, and gather your 1099-R and 5498 for filing.
7. Call a CPA or fee-only advisor for any conversion above roughly $50,000 or any backdoor Roth, since the planning is complex and conversions cannot be undone.

This article is educational and not a substitute for advice from a licensed tax professional for your specific situation. A six-figure conversion, a mixed-basis IRA, or a conversion near a Medicare or Social Security threshold is complex enough to warrant a CPA or tax advisor, who can model the multi-year tax impact for a few hundred dollars.

FAQs

Is there a limit on how much I can convert to a Roth in one year? No. For tax year 2025, there is no dollar limit and no income limit on conversions. You can convert any amount, but you owe ordinary income tax on the pre-tax portion you convert.

Can I convert only the after-tax part of my IRA? No. The pro-rata rule blocks this. The IRS treats all your traditional, SEP, and SIMPLE IRAs as one pot, so each conversion is part after-tax and part taxable, based on your overall basis ratio.

What is the deadline for a 2025 Roth conversion? December 31, 2025. A conversion counts in the year the money actually moves, unlike contributions, which you can make until the April filing deadline. Miss it and the conversion falls into 2026.

How much tax will I owe on a partial conversion? Your ordinary income tax rate applies to the converted pre-tax amount. The conversion stacks on top of your other income, so the rate depends on which 2025 bracket the converted dollars land in.

Will a conversion raise my Medicare premiums? Yes, possibly. A conversion raises your MAGI, and Medicare uses MAGI from two years prior to set IRMAA surcharges. A 2025 conversion can raise your 2027 Part B and Part D premiums if it crosses a threshold.

Can I undo a Roth conversion if I change my mind? No. Conversions made on or after January 1, 2018 cannot be recharacterized, per the IRS. Once you convert, the decision and its tax bill are final, so plan the amount carefully first.

Do I have to take my RMD before converting? Yes. In any year you owe an RMD, you must take the full RMD first; only amounts above it can be converted. The RMD age is 73 for those born 1951–1959 and 75 for those born in 1960 or later.

Should I pay the conversion tax from the IRA? No, generally not. Paying from outside funds keeps 100% of the converted money growing tax-free and avoids a possible 10% early-withdrawal penalty on any amount withheld if you are under 59½.

What form do I file for a Roth conversion? Form 8606. You file it with your tax return to report the conversion and any after-tax basis. Your custodian sends a Form 1099-R, and the receiving Roth custodian issues a Form 5498.

Does my state tax a Roth conversion? It depends. No-income-tax states like Florida and Texas do not tax it. Most income-tax states tax the conversion as ordinary income, like the federal rule. Confirm with your state revenue department.

Can a high earner who can’t fund a Roth still convert? Yes. The income limit applies only to direct Roth contributions, not conversions. This is the basis of the “backdoor Roth,” though the pro-rata rule can make it taxable if you hold pre-tax IRA money.

Is each conversion subject to its own five-year rule? Yes. Each conversion year starts a separate five-year clock. Withdrawing converted principal before five years pass may trigger a 10% penalty if you are under 59½, even though tax was already paid.

This article reflects federal rules as of June 2026 and covers tax years 2025 and 2026. Confirm current figures before you file. Word count: approximately 3,650.