Roth Conversion Tax Bracket Calculator (2026)

How much should you convert this year? Enter your other income and this calculator tells you exactly how much you can convert to fill the 22% or 24% bracket — without crossing into a higher rate. It also flags whether the conversion would trigger a Medicare IRMAA surcharge.

How to read the results

"Fill 22% bracket" is the classic golden-window target. You pay 22% on the conversion now. If you leave those dollars in a traditional IRA, you'll pay your future marginal rate — often 32-37% — when RMDs force withdrawals starting at 73 or 75. The 10-15 percentage point spread is where the real money is.

"Fill 24% bracket" makes sense when your projected post-RMD rate is 32%+ — typical for a couple with a large IRA and Social Security income stacking on top. The 8-point spread (24% now vs. 32% later) still justifies the higher rate today, especially for large balances.

IRMAA timing is critical. 2026 Medicare premiums are already locked based on your 2024 income. What you convert in 2026 affects your 2028 premiums. The calculator flags the relevant IRMAA tier using 2026 thresholds as a planning proxy — actual 2028 thresholds will be set in late 2027 and will likely be ~3-6% higher.

What this calculator doesn't model

• Social Security taxation stacking. Conversion income triggers 50-85% of SS to become taxable, increasing the effective marginal rate. Not modeled here.
• State income tax. Nine states (FL, TX, NV, WA, WY, SD, AK, TN, NH) have no income tax on conversions. CA, NY, MN, and others charge 5-13% on top of federal.
• Pro-rata rule. If you have after-tax IRA contributions (non-deductible, basis tracked on Form 8606), every conversion is partially tax-free. This lowers your actual tax cost.
• 5-year rule. Funds from each conversion have a separate 5-year clock for penalty-free access — relevant mostly if you're under age 59½.
• OBBBA senior deduction. If you're 65+ with MAGI under $75,000 (single) or $150,000 (MFJ), you may qualify for an additional $6,000 deduction per person under the One Big Beautiful Bill Act.² This isn't modeled because the phaseout depends on post-conversion MAGI — a circular calculation. If eligible, manually add it in the itemized deduction field instead of using standard.
• Multi-year optimization. The right conversion in year 1 changes in year 2 as the balance grows, brackets inflate, Social Security starts, and RMDs loom. A specialist builds a 10-15 year projection.