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Roth conversion calculator

Free, no signup. A Roth IRA conversion tax calculator: the 2026 federal and state tax when you convert an IRA or 401(k) to a Roth, how much you can convert to fill each bracket, and what it does to your Medicare premiums two years later. Social Security taxation is included.

Updated · By Berkay Kolay

The calculator

Tax on the conversion$6,42212.8% of $50,000
Federal bracket10% → 12%Before and after converting
Medicare IRMAA in 2028No changeMAGI $29,000 → $100,500 (illustrative 2028 tiers)

Converting $50,000 adds about $6,422 of 2026 income tax, 12.8% of the amount converted. That is more than your bracket rate because the conversion also makes more of your Social Security taxable.

How much to convert to fill a bracket

The conversion that brings your 2026 taxable income to the top of each bracket, on the income you entered above. It accounts for the Social Security that the conversion makes taxable and for deductions that phase out.

Conversion to reach the top of each federal bracket, its tax and its IRMAA effect
Fill up toConvertTax on itIRMAA change in 2028
12% bracket$93,150$12,050None
22% bracket$197,840$36,380+$2,378 a year
24% bracket$389,900$82,688+$13,176 a year
32% bracket$498,800$117,536+$13,176 a year

How a Roth conversion is taxed

The amount you convert from a traditional IRA or 401(k) is ordinary income in the year you convert, taxed at your bracket rate. It also counts in the combined income that decides how much Social Security is taxable, so inside that range a conversion can cost more than your bracket suggests. It raises modified AGI, which sets Medicare IRMAA two years later and, before 65, the ACA premium tax credit. There is no 10% penalty on the conversion itself, at any age.

When converting tends to pay

A conversion pays off when the rate you pay now is lower than the rate the money would face later. That is often true in the years between retiring and claiming Social Security or starting RMDs, before one spouse dies and the survivor files single, or when heirs in higher brackets would otherwise inherit a traditional IRA they must empty within ten years. It tends not to pay if you would have to use IRA money to pay the tax, or if your rate later will be lower. Killion’s planner compares conversion rules over a whole retirement across 1,000 simulated markets when you turn tax on in a paid plan. The withdrawal order calculator shows the order the accounts are spent in.

Deadlines and the five-year rule

  • Conversions count in the calendar year they happen; the deadline is December 31.
  • A conversion cannot be undone. Recharacterizing a conversion back to a traditional IRA ended in 2018.
  • Before 59½, each conversion has its own five-year clock before you can withdraw it without the 10% penalty. After 59½ that clock no longer matters for the converted amount.
  • RMDs cannot be converted: you take the year’s RMD first, then convert.

Assumptions and sources

One 2026 return under current law, with the standard deduction, no alternative minimum tax and no local tax. The same tax engine runs inside Killion’s planner when you turn tax on in a paid plan. Estimates for planning, not tax advice. The IRMAA column uses the illustrative 2028 tiers from the IRMAA calculator, counting each person on the return who will be 65 by 2028.

Figures checked on against IRS Rev. Proc. 2025-32, 2026 inflation adjustments (PDF), IRS Publication 915, Social Security and equivalent railroad retirement benefits and IRS Publication 590-B (2025), Distributions from IRAs.

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Frequently asked questions

How much tax will I pay on a Roth conversion?
The amount you convert is ordinary income, taxed at your bracket rate in the year you convert. In the Social Security phase-in range it costs more, because each converted dollar can make 85 cents of benefits taxable too: 22.2% in the 12% bracket.
How much should I convert to a Roth each year?
A common approach is to convert up to the top of your current bracket, as long as that rate is lower than the one you expect later. The calculator shows the conversion that fills each bracket on your own income.
Is there a deadline for Roth conversions?
Yes, December 31. A conversion counts in the calendar year it happens, unlike IRA contributions, which can be made until the April filing deadline.
Do Roth conversions affect Medicare premiums?
Yes. A conversion raises modified AGI, and Medicare sets IRMAA from your MAGI two years earlier, so a 2026 conversion can raise your 2028 Part B and Part D premiums.
What is the five-year rule for Roth conversions?
Each conversion has its own five-year period before it can be withdrawn without the 10% penalty if you are under 59½. After 59½ the penalty does not apply to converted amounts.
Can I undo a Roth conversion?
No. The 2017 tax law ended recharacterization of conversions starting in 2018, so a conversion is final once it is done.
Can I convert my RMD to a Roth?
No. Required minimum distributions cannot be converted. In a year you owe an RMD, take it first; anything you convert after that counts toward your conversion.
Can I use this for a 401(k) to Roth IRA conversion?
Yes. Converting pre-tax 401(k) money to a Roth, inside the plan or by rolling it to a Roth IRA, is taxed the same way as an IRA conversion: the amount converted counts as ordinary income for the year. Enter it as the conversion amount.
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