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Roth Conversion Tax-Bracket Calculator

See which federal brackets a proposed Roth conversion would fill, the estimated extra tax, and how much room remains in your target bracket.

Est. additional federal tax$8,700

Understanding this calculator

A Roth conversion moves money from a traditional IRA or 401(k) into a Roth IRA. You pay ordinary income tax on the converted amount now; in exchange, qualified withdrawals later are tax-free and the money escapes future required minimum distributions. The whole game is choosing the amount and the year so the conversion is taxed at rates you're comfortable with.

Many retirees find a window between retiring and starting Social Security or RMDs when their taxable income dips. This tool shows exactly how a conversion stacks on top of your other income — which brackets it fills, where it spills into the next one, and how much room you have left if you're targeting the top of, say, the 22% bracket.

One caution: a conversion raises your modified adjusted gross income, which can ripple into Medicare IRMAA surcharges two years later, taxation of Social Security benefits, and income-based credits. The calculator flags IRMAA threshold crossings, but talk to a tax professional before executing a large conversion.

Assumptions and methodology

  • Conversion dollars are treated as ordinary income stacked on top of your other ordinary income for the selected tax year.
  • If you enter gross income, the standard deduction (plus age-65+ additions and the 2025–2028 senior deduction, with its 6% phase-out) is applied automatically.
  • The bracket chart shows how the conversion itself is sliced across brackets; additional tax is the difference between tax with and without the conversion.
  • The optional state estimate is a flat rate you choose times the conversion — state rules vary too much for more precision here.
  • IRMAA context compares your approximate MAGI before and after against the displayed year's tiers; actual IRMAA uses your MAGI from two years prior.
  • Not modeled: capital gains interactions, Social Security taxation, credits and phase-outs, state specifics, the pro-rata rule for after-tax basis, and withholding strategy.

Last reviewed August 30, 2026. Year-specific figures show their tax or data year in the tool; data is reviewed when the IRS, SSA, and CMS publish annual updates.

Common questions

Is this a recommendation to convert?

No. It's an educational view of the tax mechanics. Whether converting makes sense depends on your current vs. future rates, cash to pay the tax, Medicare timing, heirs, and more — decisions worth making with a tax professional.

Why does the calculator warn about Medicare?

IRMAA surcharges are cliffs based on your MAGI from two years earlier. A conversion that crosses a threshold can raise both spouses' Part B and D premiums for a full year.

Can I convert just enough to fill my current bracket?

That's a common approach — the "room in target bracket" figure shows how much more conversion fits before the next rate kicks in.