Roth Conversion Calculator: Tax & Break-Even (2026)

Calculation	Estimate
Federal tax without conversion	$7,904
Federal tax with conversion	$11,504
Incremental federal tax	$3,600
State tax estimate	$1,500
Future Roth value, before tax-funding cost	$64,023
Future value of tax-funding cost	$10,884
Traditional value after assumed future tax	$49,938

The short answer

A Roth conversion can be useful when the tax rate paid now is lower than the rate avoided later—but the household side effects matter.

A Roth conversion moves eligible money from a Traditional IRA or another pre-tax retirement account into Roth. The taxable portion is generally included in income for the conversion year. Future qualified Roth IRA distributions may be tax-free, and an original Roth IRA owner does not have lifetime required minimum distributions under current law.

The decision is not simply “pay tax now or never pay tax.” The real comparison is the incremental tax created now versus the future tax that may apply if the money remains Traditional. A fair estimate must also recognize where the current tax payment comes from. Spending outside savings on tax has an opportunity cost; withholding tax from the conversion leaves less money inside Roth.

What this calculator answers

What would one conversion add to my 2026 tax—and what future tax rate would make that trade approximately break even?

The deterministic engine calculates federal tax before and after the conversion using the same versioned 2026 brackets. It does not ask AI to invent a tax result.

How the Roth conversion calculator works

Start with taxable income.Enter expected federal taxable income after deductions but before the conversion. This is closer to Form 1040 line 15 than gross income or AGI.
Add the taxable conversion.The public model assumes the entire converted amount is untaxed pre-tax money. It shows how much lands in each federal bracket.
Calculate incremental federal tax.The engine subtracts federal tax without the conversion from federal tax with the conversion. It does not multiply the whole amount by one headline rate.
Add a state estimate.Because state rules differ, you supply a marginal rate. Enter zero in a state with no applicable income tax or retirement-income tax.
Compare future after-tax values.The Roth path is reduced by the future value of the current tax-funding cost. The Traditional path is reduced by your selected future marginal withdrawal rate.

Core calculation

Federal conversion tax = federal tax with conversion − federal tax without conversion
Conversion tax now = federal conversion tax + estimated state tax
Net Roth path = future Roth value − future value of today’s tax-funding cost
Traditional path = future pre-tax value × (1 − assumed future tax rate)

Returns, fees, and future rates are assumptions—not forecasts. A different return does not rescue a conversion from an unfavorable tax-rate trade when both paths hold the same investments.

Why “fill the bracket” is useful—but incomplete

A common planning method is to convert only enough to reach the top of a selected bracket. For 2026, the 12% federal bracket ends at $50,400 of taxable income for single filers and $100,800 for married couples filing jointly. The 22% bracket ends at $105,700 and $211,400, respectively. The calculator’s bracket-fill buttons use these taxable-income ceilings.

Crossing a bracket is not automatically a mistake. Only the dollars above the threshold enter the next federal rate. But taxable income is not the only threshold that matters. Modified adjusted gross income can influence ACA premium tax credits; Medicare IRMAA generally uses an income lookback; and conversions can cause more Social Security benefits to become taxable. Credits, deductions, NIIT, capital-gain rates, and state benefits may also have their own thresholds.

Taxable income is not the same as gross income

Which income number belongs in this public calculator?
Income measure	Use here?	Why
Salary or gross household income	No	It ignores adjustments, retirement income, deductions, and other taxable items.
Adjusted gross income (AGI)	Not directly	Federal tax brackets apply after the standard or itemized deduction and other taxable-income adjustments.
Taxable income before conversion	Yes	This is the amount the versioned federal bracket calculation uses before adding the conversion.
Modified AGI for ACA or Medicare	No	These programs use separate definitions and timing rules that require a household calculation.

If you are estimating before year-end, start with a tax projection rather than copying last year’s taxable income without adjustment. Wages, pensions, withdrawals, realized gains, business income, deductions, and filing status may have changed.

Paying conversion tax from savings versus the IRA

Paying conversion tax with money outside the retirement account generally allows the full requested amount to enter Roth. The calculator still treats that cash as a cost: it grows the tax payment at the same modeled account return and subtracts that opportunity cost from the Roth path.

If tax is withheld from conversion dollars, less reaches Roth. For someone under age 59½, the amount not rolled into Roth may also be treated as an early distribution and face the 10% additional tax unless an exception applies. A direct trustee-to-trustee conversion does not by itself create that additional tax on the amount successfully converted, but later Roth withdrawals can be subject to separate five-year rules.

IRA basis and the pro-rata rule

This public calculator assumes fully taxable pre-tax money. That is a clear starting point for many pre-tax workplace balances, but it is not a Form 8606 calculation. If you made nondeductible contributions to any Traditional, SEP, or SIMPLE IRA, the taxable portion of an IRA conversion can depend on aggregate year-end values and basis across those IRAs—not solely on the account being converted.

Do not label one IRA “after-tax” and assume only that account can be converted tax-free. Confirm basis records and Form 8606 before using conversion instructions. Roth conversions made after 2017 generally cannot be recharacterized back to Traditional if the tax result is larger than expected.

RMD years need the correct order

An RMD for the year is not eligible to be rolled over or converted. If you are subject to an RMD, the required distribution generally must come out before additional eligible dollars are converted. Use the RMD Calculator to estimate the required amount, but confirm account aggregation and ordering with the custodian or plan administrator.

Reducing a Traditional balance through conversions before future RMD years may reduce later required distributions, but this one-year calculator does not project an entire RMD schedule, taxable Social Security, survivor filing-status changes, or Medicare surcharges. Those interactions belong in the household Snapshot.

What the result includes—and what needs a complete tax projection

Included

2026 single and married-filing-jointly federal brackets
Incremental federal tax calculation
User-entered state marginal rate
Outside-cash or withholding tax source
Steady-return future comparison and break-even rate

Not included

IRA basis and Form 8606 pro-rata calculation
Taxable Social Security, ACA, IRMAA, NIIT, credits, or deductions
RMD eligibility and distribution ordering
Five-year withdrawal tests and account-specific plan rules
Future law, market returns, or a complete tax return

Roth conversion calculator FAQ

How is a Roth conversion taxed?

The taxable part of a Traditional IRA or eligible pre-tax plan amount converted to Roth is generally included in gross income for the conversion year. This calculator estimates the incremental federal tax using 2026 brackets and treats state tax as a separate user-entered rate.

Is there an income limit for Roth conversions?

The income limits that restrict regular Roth IRA contributions do not generally prevent a Traditional IRA-to-Roth IRA conversion. Income still matters because the conversion can raise tax and affect other income-based rules.

Can I convert my required minimum distribution?

No. An amount that must be distributed as an RMD for the year is not eligible for rollover or conversion. In an RMD year, the required amount generally must be distributed before additional eligible dollars are converted.

Should I pay conversion tax from the IRA?

Paying tax from outside funds usually leaves more of the conversion inside Roth. Withholding from conversion dollars leaves less invested and, before age 59½, the withheld distribution may face the 10% additional tax unless an exception applies.

Does this calculator apply the IRA pro-rata rule?

No. It assumes fully taxable pre-tax money. If any Traditional, SEP, or SIMPLE IRA contains nondeductible basis, Form 8606 and the year-end value of all such IRAs can change the taxable portion.

Can a Roth conversion affect Medicare or ACA costs?

Yes. A conversion raises income and may affect ACA premium tax credits in the same year or Medicare IRMAA based on the applicable lookback year. Those household effects are outside this single-year public calculator.

Official sources

Educational use only. This calculator is not tax, investment, legal, or fiduciary advice and does not prepare a tax return. Roth conversions can be irreversible and may affect multiple federal, state, healthcare, and benefit rules. Confirm taxable income, basis, RMD status, payment source, and estimated-tax requirements before acting.

Estimate the tax cost—and the future value—of converting this year.

Test one Roth conversion year.

Your conversion stays inside the 12% federal bracket.

Conversion and keeping Traditional are approximately equal at 17.0%.