Retirement tax · 2026 federal and state brackets
Roth Conversion Calculator
Estimate how a traditional IRA conversion fills 2026 federal and selected-state brackets, how Form 8606 basis may reduce the taxable portion, and whether tax is paid from outside cash or the conversion itself.
Quick estimate
Estimate the tax cost of a Roth conversion
Estimated federal and state tax
$16,13632.3% of the amount converted under these assumptionsTaxable conversion
$50,000Basis allocated
$0A simplified 2026 incremental ordinary-income estimate. It does not model every Form 8606 transaction, retirement-income exclusions, Social Security taxation, Medicare premiums, ACA credits, deductions, credits, local tax, or penalties on amounts withheld from the conversion.
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How this calculator works
A taxable Roth conversion is added to ordinary income for the year. The calculator computes 2026 federal tax before and after the taxable conversion; the difference is the estimated federal tax attributable to the conversion.
IRA basis is generally allocated pro rata
If traditional, SEP, or SIMPLE IRAs contain nondeductible basis, Form 8606 generally allocates basis across distributions and conversions rather than letting you convert “after-tax dollars first.” This screening model divides entered aggregate basis — capped at the denominator it sits in — by the entered pro-rata denominator, or by the conversion amount itself when no total IRA value is entered, and applies that percentage to the conversion.
Paying tax from outside cash preserves the conversion
With outside cash, the full conversion can reach the Roth. Withholding tax from the IRA reduces the amount converted and may create an early-distribution issue for the withheld portion. The tool shows the immediate tradeoff but not any additional penalty.
Bracket tax is only one conversion cost
A conversion can affect taxable Social Security, Medicare income-related premiums, Affordable Care Act premium credits, capital-gain bands, deductions, credits, net investment income tax, and state tax. Those interactions can create an effective marginal rate different from the displayed bracket-only estimate.
Size and time the conversion carefully; a decline in account value does not generally let you undo the completed conversion.
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Worked example
A single filer with $80,000 of other 2026 taxable income converts $50,000. With no IRA basis, the full $50,000 is taxable and crosses from the 22% bracket into the 24% bracket.
If $25,000 of basis sits inside a $100,000 pro-rata denominator, an estimated 25% of a conversion is nontaxable—not the first $25,000 converted.
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Questions people ask
Is every Roth conversion taxable?
No. Previously taxed IRA basis and certain direct rollovers of after-tax plan amounts can reduce the taxable portion, but reporting and aggregation rules matter.
Does a conversion count toward the annual Roth IRA contribution limit?
No. A conversion is different from a regular contribution, though eligibility and plan-specific rollover rules still apply.
Can I undo a Roth conversion?
Conversions made in 2018 or later generally cannot be recharacterized back to a traditional IRA.
What value belongs in the pro-rata denominator?
Form 8606 uses aggregate traditional, SEP, and SIMPLE IRA information including year-end value and relevant distributions/conversions. Use the form instructions for the actual tax year.
Should I convert enough to fill one bracket?
Bracket filling is one strategy, but it can ignore Medicare premiums, benefits, credits, state tax, future required distributions, estate plans, and future tax rates.
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Sources and model basis
This calculator is for tax year 2026 — the return filed in early 2027. Rates, brackets, deductions and limits are the ones in force for 2026, including changes enacted during 2026 that apply retroactively to the whole year. It does not estimate any other year.
Published rules and formulas are linked below. Values supplied by the visitor remain scenario inputs, not factual claims.
- IRS Form 8606 and instructionsReporting nondeductible basis, IRA distributions, and Roth conversions
- IRS Publication 590-BTraditional and Roth IRA distribution and conversion rules
- IRS 2026 inflation adjustments2026 ordinary-income brackets and standard deductions