How much tax does a Roth conversion cost in 2026? Bracket by bracket

By DecisionSheet · Updated October 27, 2026 · 2026 tax figures

A Roth conversion moves money from a traditional IRA (or a 401(k)) into a Roth IRA. You pay income tax on the amount now, and qualified withdrawals later are tax-free. The question is always the same: is the rate you pay now lower than the rate the money would pay if it stayed put?

The rate now is harder to see than it looks. The converted amount is ordinary income for the year, so the cost is the tax on your return with the conversion less the tax without it, and for retirees that is often more than the bracket rate. DecisionSheet's Roth conversion tax calculator works it out from the 2026 rules. This page runs it on five households.

A conversion counts in the year it is made, so a 2026 conversion has to be completed by December 31, 2026. It cannot be undone: conversions made in 2018 or later cannot be recharacterized (IRS Publication 590-A).

What a conversion adds to your taxable income

Three things move when you convert, not one.

The conversion itself. Each converted dollar is a dollar of income, taxed on the 2026 brackets after the standard deduction ($32,200 joint, $16,100 single, plus $1,650 per spouse 65 or older on a joint return and $2,050 for a single filer).

Social Security. None of your benefits is taxable until your other income plus half your benefits passes $32,000 on a joint return ($25,000 single). Past that, 50% of each extra dollar of income brings a dollar of benefits into income, and past $44,000 ($34,000 single) it is 85%, until 85% of the benefits is taxable (26 U.S.C. §86; IRS Publication 915). In that range, each converted dollar adds $1.85 of taxable income. This is often called the tax torpedo. None of these thresholds is indexed for inflation.

The senior deduction. From 2026 through 2028, each filer 65 or older deducts $6,000, reduced by 6% of AGI over $150,000 on a joint return ($75,000 otherwise), for each spouse (26 U.S.C. §151(d)(5)). A conversion that pushes AGI into that range loses deduction as well.

The example: a retired couple in the 12% bracket

The household. Married filing jointly, both over 65.
Income. $40,000 a year from a pension and IRA withdrawals, plus $50,000 of Social Security.
The plan. Convert $60,000 of traditional IRA money in 2026, paying the tax from savings.

Calculator summary tiles for a married couple, both over 65, with $40,000 of other income and $50,000 of Social Security converting $60,000: federal tax added $9,269, average rate 15.4%, the next $1,000 costs 12.0%, and $5,800 of room left in the 12% bracket.

Without a conversion, $23,850 of their benefits is taxable. Their AGI is $63,850, and after the $35,500 standard deduction and the $12,000 senior deduction they have $16,350 of taxable income and owe $1,635, all in the 10% bracket.

With it, the conversion brings $18,650 more of their benefits into income, up to the 85% cap of $42,500. Taxable income rises by $78,650, not $60,000. Their AGI stays under $150,000, so the senior deduction is untouched. Tax rises to $10,904: a cost of $9,269, or 15.4% of the amount converted. Open this scenario.

Without-and-with table for the same couple: taxable Social Security $23,850 then $42,500, AGI $63,850 then $142,500, taxable income $16,350 then $95,000, federal tax $1,635 then $10,904.

Is 15.4% a good price? If the money stayed in the IRA and came out later at 22%, it would pay $13,200. Converting is $3,931 ahead in today's dollars. That figure holds whatever the money earns, as long as both choices grow at the same rate. Paying the tax from savings tilts it a little further toward converting, because that cash would otherwise have been taxed on its own growth.

How much fills each bracket

The calculator also works out how much the same couple can convert before each bracket fills, and what it costs:

Bracket table for the same couple: $4,567 fills the 10% bracket for $845 of tax, 18.5% on average; $65,800 fills the 12% bracket for $9,965 of tax, 15.1% on average; $164,732 fills the 22% bracket for $34,297 of tax, 20.8% on average.

The 10% bracket. It fills after only $4,567, at an average of 18.5%. That is 10% times $1.85.
The 12% bracket. It fills at $65,800, which adds $9,965 of tax, 15.1% on average. Taxable income then reaches $100,800, the top of the bracket. So the $60,000 plan leaves $5,800 of room. Open the $65,800 conversion.
The 22% bracket. It needs $164,732, and its average rate is 20.8%.

A conversion that stops at the top of a bracket is the usual plan. The chart shows why that is not the whole story. It plots the tax on each next $1,000 converted:

Chart of the federal tax on each next $1,000 converted, from $0 to $200,000, for the same couple: 18.5% at first, 22.2% until about $21,941, then 12% to about $65,800, then 24.64% while the senior deduction phases out, peaking at 26.88%; the dashed line marks the 22% rate later.

Up to $21,941. The first dollars cost 18.5%, then 22.2%, while benefits are still becoming taxable. That is more than 22% inside what is nominally the 12% bracket.
Past that point. The benefits are at the 85% cap, and the rate drops back to a plain 12%.
From $67,500. That is just past the top of the 12% bracket, where AGI passes $150,000. Both senior deductions start to shrink, and the 22% bracket costs 24.64%.
The peak. The rate reaches 26.88% near $165,000, where the 24% bracket starts before the senior deduction is gone.

So the cheap dollars here are the ones past the torpedo and below the top of the 12% bracket. The calculator shows the rate on the next $1,000 at your amount, so you can see where you are.

Before Social Security starts: the gap years

A couple who retired at 62 and live on savings until claiming Social Security has a much cheaper window. Take $30,000 a year of other income, no benefits yet, and neither spouse 65. Their income is under the $32,200 standard deduction, so they owe nothing without a conversion, and the first $2,200 converted is tax-free.

Converting $60,000 costs $6,440, only 10.7%. They can convert $103,000 before leaving the 12% bracket, for $11,600 (11.3%). Open it.

That is more conversion, at a lower rate, than the couple above can do once their benefits have started. Benefits that are not yet being paid cannot become taxable, so the torpedo does not apply. This is why the years between retiring and claiming Social Security (or reaching required minimum distributions) are the usual time to convert.

When it does not pay: a worker in the 22% bracket

A single filer earning $120,000, with $103,900 of taxable income, is near the top of the 22% bracket. Converting $20,000 puts the first $1,800 at 22% and the rest at 24%, for $4,764 (23.8%). At 22% later, the conversion is $364 behind. Open it.

The comparison turns on the rate later. If this worker expects 24% in retirement, it is within the calculator's 0.5-point tie band. Converting a little less, to stay in the 22% bracket, makes it a wash at 22%.

The senior deduction phase-out

A single retiree, 66, with $70,000 of pension and IRA income and $30,000 of Social Security, already has $25,500 of benefits taxable, the 85% cap. So a conversion adds no more Social Security income. But their AGI is over $75,000, so the conversion shrinks their senior deduction from $4,770 to $2,970.

Converting $30,000 costs $6,996: 23.32%, the 22% bracket plus 6% of it. At 22% later, converting is $396 behind. Open it.

What decides it

Your rate later, and who pays it. Required minimum distributions, a surviving spouse filing single, and heirs who inherit the IRA can all face a higher rate than you do today. A lower income in retirement, or a move to a state without income tax, points the other way. How much your RMD will be, and its tax shows how fast RMDs grow.
Where your Social Security is. Below the point where 85% of benefits is taxable, each converted dollar adds $1.85 of income. Past it, a conversion costs only the bracket rate. Before benefits start, there is no torpedo at all.
AGI thresholds. The senior deduction phase-out starts at $150,000 joint ($75,000 otherwise). Medicare premium surcharges for 2028 are set from 2026 income. And above $250,000 joint ($200,000 otherwise), investment income owes the 3.8% net investment income tax. The conversion is not investment income, but it raises AGI.
Where the tax comes from. Paying it from savings keeps the whole amount in the Roth. Paying it out of the IRA converts less, and before 59½ the withheld part can owe a 10% additional tax.

Assumptions and limits

Federal income tax only, on the 2026 brackets and standard deduction in Rev. Proc. 2025-32, with the age-65 additional deduction and the senior deduction of Pub. L. 119-21. All income other than Social Security is taxed as ordinary income. Capital gains rates, credits, the alternative minimum tax and the net investment income tax are not modeled. State tax is a flat rate on the amount converted; every example here sets it to zero.
Tax-exempt interest counts toward the Social Security test but is not an input. Married filing separately is not modeled.
The IRA is assumed to hold only pre-tax money. If you have made nondeductible contributions, part of the conversion is tax-free under the pro-rata rule (Form 8606), and the cost is lower: how the pro-rata rule taxes a backdoor Roth works it out.
The comparison with later uses one rate on the whole amount and assumes both choices grow at the same rate before tax, with the conversion's tax paid from cash outside the IRA. It ignores Medicare premium surcharges, the five-year rule on withdrawing converted amounts before 59½, and estimated tax payments, which a large conversion can require (IRS Publication 505). A required minimum distribution for the year cannot be converted, and counts as other income.
This is a model of tax rules, not tax advice.

Method and sources

The model is calculateRothConversion in the Roth conversion tax calculator. It computes the year twice, without and with the conversion. Each time it takes the taxable part of Social Security from other income plus the conversion, then AGI, the standard and senior deductions, and tax on the progressive brackets. The cost is the difference. Each bracket's fill is the conversion that brings taxable income exactly to the bracket's top, solved against the same model. The rate on the next $1,000 is the extra tax on $1,000 more. Every figure on this page comes from runs of the model on the inputs in the scenario links, and the statutory figures are read from the site's tax constants for 2026. The calculator was cross-checked against an independent model of the same rules.

26 U.S.C. §86: taxable Social Security, the $25,000/$32,000 base amounts and the $34,000/$44,000 adjusted base amounts.
IRS Publication 915: the same thresholds, and that tax-exempt interest is counted.
IRS Publication 590-A: conversions are included in income in the year converted, the 10% additional tax does not apply to the amount converted, required distributions cannot be converted, and conversions made in 2018 or later cannot be recharacterized.
26 U.S.C. §151(d)(5): the $6,000 senior deduction and its 6% phase-out.
Rev. Proc. 2025-32: 2026 tax brackets, the standard deduction and the $1,650/$2,050 additional standard deduction for age 65.
IRS, Questions and Answers on the Net Investment Income Tax: the $250,000/$200,000 thresholds, not indexed, and IRA distributions are not net investment income.
42 U.S.C. §1395r(i): Medicare Part B premium surcharges use modified AGI from the second year before.

Open this scenario in the calculator

All figures on this page come from the Roth Conversion Tax calculator. Change any input there and the numbers update.