How much tax will a Roth conversion cost me?

A Roth conversion is taxed as ordinary income stacked on top of your existing income. For example, a single filer with $90,000 taxable income converting $50,000 pays about $11,733 in extra federal tax, an effective conversion rate of roughly 23.5%.

Will a conversion push me into a higher tax bracket?

It can. The conversion adds to your taxable income, so part of it may be taxed at a higher marginal rate. In the example above, $90,000 of income sits in the 22% bracket, but the conversion pushes the top of the stack into the 24% bracket at $140,000.

Is the whole conversion taxed at my top rate?

No. Only the portion that crosses into a higher bracket is taxed at that higher rate. That is why the effective conversion rate (23.5% in the example) sits between the 22% and 24% marginal rates rather than at a single flat number.

Does this include state tax?

No. This tool estimates only federal income tax on the conversion. State income tax, Medicare IRMAA surcharges, and the 3.8% net investment income tax are separate and can add meaningfully to the total cost.

What is the Roth IRA Conversion Calculator?

Estimate the federal tax cost of converting traditional IRA funds to a Roth IRA in 2026. Adds the conversion amount to your taxable income, applies the 2026 federal brackets, and shows the incremental tax, your new marginal bracket, and the effective conversion tax rate. It runs free in your browser on Gera Tools, with nothing uploaded.

Roth IRA Conversion Calculator

Name: Roth IRA Conversion Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

Converting traditional IRA money to a Roth IRA means paying income tax now in exchange for tax-free growth and withdrawals later. This calculator stacks the conversion on top of your 2026 taxable income, applies the federal brackets, and shows the extra tax, your new marginal bracket, and the effective rate on the conversion.

How it works

A Roth conversion counts as ordinary income in the year you convert. The tool computes your tax twice using the 2026 progressive brackets and takes the difference:

conversionTax = tax(income + conversion) − tax(income)
effectiveRate = conversionTax / conversion

Because the brackets are progressive, only the part of the conversion that crosses a bracket boundary is taxed at the higher rate. Your input is treated as taxable income already (after the standard deduction), so the deduction is not applied again.

Example

A single filer has 90,000 dollars of taxable income and converts 50,000 dollars. Tax on 90,000 is about 14,714 dollars. Adding the conversion brings taxable income to 140,000 dollars, where the tax is about 26,447 dollars.

conversionTax = 26,447 − 14,714 = 11,733
effectiveRate = 11,733 / 50,000 = 23.47%

The conversion pushes the top of the stack from the 22% bracket into the 24% bracket, so the new marginal rate is 24%. Notice that the effective conversion rate (23.47%) falls between the 22% and 24% rates — only the portion of the conversion that crossed the bracket boundary was taxed at 24%.

Why people convert to Roth

The primary appeal of a Roth conversion is that future growth and qualified withdrawals are entirely tax-free. If you expect to be in the same or a higher bracket in retirement than you are now, paying tax on a conversion at a lower current rate can be significantly more valuable than deferring tax to a higher future rate.

A Roth IRA also has no required minimum distributions (RMDs) during the owner’s lifetime, unlike a traditional IRA. This gives more flexibility in retirement income planning and can reduce taxes on Social Security benefits by keeping gross income lower.

When a partial conversion makes sense

Converting the entire balance in one year may push you into a higher bracket than necessary. A common strategy is to convert up to the top of your current bracket each year — for example, converting just enough to fill the 22% bracket before crossing into 24%. Repeating this over several years can shift a large balance at a consistently moderate rate without ever triggering the highest marginal brackets.

Things this calculator does not cover

State income tax — most states with an income tax treat Roth conversions as ordinary income. State rates typically range from zero to over 13% and add meaningfully to the total cost.
Medicare IRMAA — higher income in the conversion year can trigger surcharges on Medicare Part B and D premiums two years later. The income-related monthly adjustment amount can add hundreds per month.
Net investment income tax (3.8%) — if modified adjusted gross income exceeds certain thresholds ($200,000 single / $250,000 married filing jointly for 2026), an additional 3.8% applies to investment income.
Pro-rata rule — if you have non-deductible IRA contributions mixed with pre-tax amounts, you cannot convert only the pre-tax portion; the conversion is treated as a proportional mix of all IRA funds.

Notes

Estimate only, not tax or financial advice. The calculator covers federal income tax using the 2026 brackets and treats the input as taxable income. Confirm your plan with a tax professional or at irs.gov.