Roth Conversion Tax Calculator

2026 IRS tax brackets

Roth Conversion Tax Calculator

See exactly how much federal tax a Roth conversion adds — and how much room you have before the next bracket.

Converting money from a traditional IRA or 401(k) to a Roth means paying ordinary income tax on the converted amount today, in exchange for tax-free growth and withdrawals later. The size of that tax bill depends entirely on which bracket the conversion pushes you into — convert too much in one year and you can bleed into a much higher rate. This calculator shows the exact federal tax cost of your conversion and how much of your current bracket you have left to fill before crossing into the next one.

Filing status
$
Wages, pensions, etc. — after deductions, before the conversion.
$
The traditional IRA / 401(k) balance you'll move.
Please enter your other taxable income to calculate.
Federal tax cost of this conversion
$0
Extra tax owed because of the conversion.
Taxable income after conversion
$0
Top marginal rate on conversion
0%
Room left in current bracket
$0
Effective rate on the conversion
0%
!

Missing income figure

Please enter your other taxable income before calculating — it's the required field.

How a Roth conversion is taxed

A Roth conversion is added directly on top of your other taxable income for the year, taxed at ordinary income rates — there's no special conversion rate. Because U.S. tax brackets are marginal, the first dollars of the conversion may be taxed at your current rate, while the later dollars get taxed at a higher rate once you cross a threshold. This is why "bracket-filling" — converting only up to the top of your current bracket — is the most common Roth conversion strategy.

The conversion tax formula
Tax before = tax(other income)
Tax after = tax(other income + conversion amount)
Conversion tax cost = tax after − tax before
Worked example — single filer, $95,000 other income, converting $40,000 (2026 brackets): tax on $95,000 ≈ $14,663; tax on $135,000 ≈ $24,929. Conversion costs ≈ $10,266 — an effective 25.7% rate on the converted amount, since part of it lands in the 24% bracket and part in the 32% bracket.

2026 federal tax brackets

RateSingleMarried filing jointly
10%$0–$12,400$0–$24,800
12%$12,401–$50,400$24,801–$100,800
22%$50,401–$105,700$100,801–$211,400
24%$105,701–$201,775$211,401–$403,550
32%$201,776–$256,225$403,551–$512,450
35%$256,226–$640,600$512,451–$768,700
37%$640,601+$768,701+

Why "bracket-filling" is the standard strategy

The most common approach is to convert just enough each year to use up the remaining room in your current bracket, then stop before spilling into the next one. This calculator shows you that exact remaining room so you can decide whether to convert the full amount now or split it across multiple years to avoid a higher marginal rate.

What this calculator does not include

  • State income tax — many states tax conversions too; this is federal-only.
  • IRMAA — a large conversion can push your Medicare premium up two years later. Check the IRMAA calculator if you're near Medicare age.
  • Net Investment Income Tax (NIIT) — the 3.8% surtax on investment income above $200k/$250k MAGI doesn't apply to the conversion itself, but a higher MAGI can affect other thresholds.
  • The 5-year rule — converted funds generally can't be withdrawn penalty-free for 5 years if you're under 59½.

You should also pay the conversion tax from outside funds where possible — using converted dollars themselves to pay the tax reduces the amount that actually lands in tax-free growth. For broader planning, see the retirement calculator, income tax calculator, and Roth IRA calculator for ongoing contribution growth projections.

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Frequently asked questions

How is a Roth conversion taxed?+
The converted amount is added to your taxable income for the year and taxed at your ordinary federal income tax rates — the same brackets that apply to wages. There's no separate "conversion tax rate"; it simply stacks on top of your other income.
What's the difference between marginal and effective rate here?+
Your marginal rate is the rate on the last dollar of the conversion — often the highest bracket it touches. Your effective rate is the total tax cost of the conversion divided by the conversion amount, which is usually lower because part of it may still sit in a lower bracket.
Should I convert my entire IRA in one year?+
Usually not, unless your balance is small. Converting a large amount in one year often pushes a big chunk into higher brackets. Most people spread conversions across several years, converting only up to the top of their current bracket each year.
Can I undo a Roth conversion if I change my mind?+
No. Roth conversion "recharacterization" was eliminated by the Tax Cuts and Jobs Act starting in 2018. Once you convert, it's permanent — so it's worth modeling the tax cost carefully before converting.
Does a Roth conversion affect my Medicare premiums?+
It can, two years later. A large conversion raises your MAGI, which is what determines IRMAA surcharges on Medicare Part B and Part D. If you're near or on Medicare, check the IRMAA calculator before converting a large amount.
Where should I pay the tax from?+
Ideally from savings outside the IRA. If you use part of the converted IRA balance itself to pay the tax, less money actually makes it into the Roth account to grow tax-free — and if you're under 59½, that withdrawn portion may also trigger an early withdrawal penalty.
Is there an income limit to convert to a Roth?+
No. Unlike direct Roth IRA contributions, which phase out at higher incomes, there's no income limit on Roth conversions — anyone with a traditional IRA or eligible 401(k) balance can convert, regardless of how much they earn.
This calculator provides general estimates only and is not tax or financial advice. It uses 2026 federal tax brackets and standard deduction figures and does not account for state income tax, the Net Investment Income Tax, IRMAA, the Additional Medicare Tax, itemized deductions, or other credits and phase-outs that may apply to your specific return. Confirm your conversion strategy with a qualified tax professional.

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