Roth conversion calculator (2026)

What is a Roth conversion?

A Roth conversion moves money from a traditional IRA or pre-tax 401(k) into a Roth IRA. The amount you convert is added to your taxable income for the year, so you pay income tax on it now. In return, the money then grows tax-free, qualified withdrawals later are tax-free, and Roth IRAs have no required minimum distributions (RMDs) for the original owner.

Put simply, a conversion pays tax at today’s rate to avoid tax at a future rate. It tends to pay off when your rate now is lower than the rate you’d pay on the same money later.

How the tax on a conversion is figured

The converted amount is stacked on top of your other income for the year, so it is taxed at your highest (marginal) rates, not your average rate. A large conversion can span more than one bracket. On top of the bracket rate, a conversion can also:

• Make more of your Social Security taxable. Up to 85% of benefits can be taxed as income rises, so each converted dollar can add more than a dollar of taxable income.
• Shrink the senior deduction. For 2025–2028, people 65 and older get an extra deduction of up to $6,000 each, reduced by 6% of income above $75,000 (single) or $150,000 (married filing jointly).
• Add state income tax, unless your state has no income tax or exempts retirement income at your age.

The calculator above includes all of these.

2026 federal income tax brackets

Taxable income is income after the standard deduction: $16,100 single, $32,200 married filing jointly, plus extra amounts for those 65 and older.

When converting can make sense

• Low-income years, often between retiring and starting Social Security or RMDs, when your bracket may be lower than it will ever be again.
• You expect a higher rate later, for example from large RMDs, a surviving spouse moving to single brackets, or tax rates rising.
• You can pay the tax from other savings, so the full amount goes into the Roth.
• You want to leave money to heirs, who generally must empty an inherited IRA within 10 years and may be in high brackets themselves.

When it may not

• You expect a lower tax rate later than today.
• You would pay the tax out of the conversion while under 59½: the withheld part counts as an early withdrawal and can owe a 10% penalty.
• The extra income would push you into Medicare IRMAA surcharges or reduce health insurance marketplace (ACA) premium credits if you’re under 65.
• You plan to leave the IRA to charity, which pays no income tax on it.

Medicare surcharges (IRMAA) and the two-year lookback

Medicare Part B and Part D premiums go up when your modified adjusted gross income (MAGI) crosses certain levels, and they use your income from two years earlier. A conversion at 63 can raise your premiums at 65. Crossing a tier by even one dollar triggers the full surcharge for that tier, so it pays to know where the lines are.

2026 IRMAA income tiers (per person)

Surcharges are per person on Medicare. The income tiers are adjusted for inflation each year.

Rules to know before converting

• No income or amount limit. Anyone can convert any amount.
• You can’t undo it. Conversions can no longer be recharacterized (reversed) since 2018.
• It counts in the calendar year you convert. There is no April deadline as with contributions; a conversion on December 31 counts for that year.
• Each conversion has its own five-year clock. If you are under 59½, withdrawing converted money within five years can owe the 10% penalty.
• Plan for the tax bill. You may need to raise withholding or make estimated tax payments to avoid an underpayment penalty.

Frequently asked questions

How much should I convert each year?

A common approach is to “fill” a bracket: convert just enough to reach the top of your current bracket (often 12%, 22% or 24%) without spilling into the next one. The “Fill a bracket” table above shows those amounts for your numbers. Whether that’s right for you depends on your whole plan, so check it with a tax professional.

Is the tax rate on a conversion my bracket rate?

Not always. If you receive Social Security or are 65 or older, a conversion can also make more benefits taxable or shrink the senior deduction, so the real rate can be higher than your bracket. The calculator shows the actual extra tax.

Should I pay the tax from the conversion or from other money?

Paying from other savings usually works out better: the full converted amount keeps growing tax-free. Paying from the conversion shrinks what goes into the Roth, and before 59½ the withheld part can owe a 10% penalty.

What doesn’t this calculator include?

It estimates one year of federal and state income tax. It does not model tax credits, the alternative minimum tax, the net investment income tax on your other investments, ACA premium credits, local taxes, state-specific partial retirement exclusions, or how conversions over many years change your future RMDs. For a year-by-year plan, use the free retirement planner.

Sources

Figures and rules on this page come from these official and independent sources. Tax rules change, so check the latest versions before you act. Last reviewed November 1, 2026.

• IRS Revenue Procedure 2025-32 (PDF): 2026 tax brackets and standard deductions
• IRS: Tax deductions for working Americans and seniors: the $6,000 senior deduction for 2025–2028 and its phase-out
• IRS Publication 590-A: contributions to IRAs, including conversions to a Roth IRA
• IRS Publication 590-B: IRA distributions, the five-year rule and required minimum distributions
• IRS: Roth IRAs
• IRS: Exceptions to tax on early distributions: the 10% additional tax before 59½
• IRS Publication 915: how Social Security benefits are taxed
• IRS: Estimated taxes
• CMS: 2026 Medicare Parts A & B premiums and deductibles: 2026 IRMAA income tiers and surcharges
• Social Security Administration: Medicare premiums: how IRMAA uses income from two years earlier
• HealthCare.gov: What income to include: income that affects marketplace premium credits
• Tax Foundation: 2026 state income tax rates and brackets