What is a Roth conversion?

Moving money from a pre-tax account (Traditional IRA/401k) into a Roth. The converted amount counts as ordinary income this year — you pay tax on it now, and in exchange it grows and withdraws tax-free forever, with no future required minimum distributions.

What does 'filling the bracket' mean?

Converting exactly enough to reach the top of your current tax bracket without spilling into the next rate. In a low-income year — between retirement and Social Security, say — you can move a lot of money at 10–12% that would otherwise come out at 22%+ later as RMDs.

When does a Roth conversion pay off?

The break-even is the blended rate you pay now: if your future withdrawal rate would be higher, converting wins; lower, it loses. Paying the conversion tax from outside (taxable) funds usually adds a further edge, because money kept in a taxable account suffers annual tax drag while Roth compounds untouched.

Is a Roth conversion reversible?

No — recharacterization was eliminated in 2018. Once converted, the tax is owed. That's why the standard practice is converting a measured amount each year against your bracket, not the whole balance at once.

Retirement & tax

Free calculator · no signup · 2026 federal brackets

Roth Conversion Calculator

Moving pre-tax money to Roth means paying the tax now — so the whole game is paying it at a cheap rate. See the exact federal tax on a conversion, walked bracket by bracket, with one-tap "fill your bracket" amounts and a multi-year schedule for clearing a balance.

Your numbers

Results update as you type.

Filing status

Other income this year (gross)

Amount to convert

Tax on this conversion

Blended rate

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Bracket after converting

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Lands in Roth

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Multi-year plan: clear a balance at your chosen bracket

Pre-tax balance to convert

From age

To age

Fill up to bracket

Balance grows at

Assumes your other income stays flat and the brackets stay where they are today. Real bracket edges rise with inflation each year, so the real room grows a little — this schedule is the conservative version.

Worth knowing: this models federal brackets + the standard deduction only (2026 figures). State tax, the senior deduction, Medicare IRMAA surcharges, and ACA subsidy cliffs aren't modeled — any of them can change the real cost of a conversion year. Conversions are irreversible: since 2018 there's no undo, so the tax is owed the moment you convert. Paying the tax from outside (taxable) funds beats withholding it from the conversion — the taxable account suffers annual tax drag that Roth doesn't.

The one idea behind every conversion strategy

Pre-tax money will be taxed exactly once — the only question is which year's rate it pays. Leave it alone and it comes out at your future rate, possibly forced out by RMDs into high brackets. Convert in a cheap year and you've bought the same dollars out at today's rate, plus tax-free growth and no RMDs forever after. That's the whole strategy: find your cheap years and use them. For most people the golden window is between retirement and age 73 — income is low, Social Security may not have started, and the brackets sit empty.

Why "fill the bracket" is the standard move

Conversion income stacks on top of your other income, so each additional dollar converted is taxed at your marginal rate — which jumps at bracket edges. Converting up to the top of your current bracket captures every dollar at the low rate and stops before the price rises. The chips above compute the exact fill amounts for your inputs (including any unused standard deduction, which shelters the first slice at 0%).

The mechanics, with the worked example

Tax on the conversion = tax(other income + conversion) − tax(other income), on taxable income after the standard deduction ($16,100 single / $32,200 joint, 2026). Example: $40,000 income + $50,000 conversion, single → the conversion spans the rest of the 12% bracket and part of 22%, costing $8,350 — a 16.7% blended rate, cheaper than its 22% top marginal because most dollars fell in 12%.

The break-even, honestly

The blended rate you pay now IS the break-even: if the money would otherwise come out below that rate, converting loses. The comparison hinges on an unknowable future rate — so treat conversions as a bet you size, not a verdict you execute. The multi-year schedule above helps with the sizing, and it's honest about the failure mode: a low bracket sometimes can't clear a large balance — growth outruns the room — and the schedule shows that instead of hiding it.

What can a Roth conversion accidentally trigger?

The tax on the conversion itself is the cost you can see coming. The surprises come from everywhere else on your return — a conversion isn't taxed off by itself, it raises your income for the year, and several other things are priced off that income.

The capital-gains interaction is the subtle one. Long-term gains ride their own ladder — 0%, 15%, 20% — and that ladder sits on top of ordinary income. A conversion is ordinary income, so it fills from the bottom and pushes gains upward. Gains that were sitting comfortably in the 0% band can get shoved into 15% by a conversion in the same year. The real cost of converting in a year you're also selling shares is higher than the conversion's own bracket suggests.

Medicare's IRMAA surcharge is the delayed one. It's a cliff, not a rate — one dollar over a threshold costs the whole tier, per person, and it's priced on your income from two years earlier. The years just before Medicare are exactly when many people convert, so a conversion at 63 can set the premium at 65, long after the decision felt finished. A one-off spike costs one year of higher premiums and then falls away; if income dropped because of a life-changing event like retirement, form SSA-44 asks SSA to use current income instead.

Three mechanical catches complete the list. A conversion is irreversible — there's been no undo since 2018. The tax is due that year, and paying it from the converted money itself shrinks the very balance being moved; outside cash keeps the transfer whole. And a conversion sized carelessly can climb into the bracket it was trying to avoid, which is why the standard shape is fill-the-bracket: convert to the top of a chosen band, stop at the line, repeat next year.

None of these is a reason not to convert. They're the reason a conversion is sized against the whole return, not just the bracket table.

Common questions

Where should the tax money come from?

Outside funds (your taxable account), if at all possible. Withhold the tax from the conversion itself and less lands in Roth — and if you're under 59½ the withheld portion is also an early withdrawal with a 10% penalty. Rule of thumb: no spare cash for the tax usually means convert less.

Does a conversion trigger the 10% early-withdrawal penalty?

The conversion itself doesn't (at any age). But each converted amount must season in the Roth for 5 years before you can touch it penalty-free if you're under 59½ — the mechanic behind the "Roth conversion ladder" that early retirees use for pre-59½ access.

Can a conversion raise my Medicare premium or ACA subsidy?

Yes — conversion income counts toward Medicare IRMAA (a two-year lookback) and ACA subsidy income, both of which have cliff-like thresholds this calculator doesn't model. Near either, check the thresholds before picking your conversion size.

Should I convert everything at once?

Almost never — a lump conversion stacks the whole amount into one year's top brackets. Spreading conversions across years, each sized to a bracket top, pays a far lower blended rate. That's exactly what the multi-year schedule computes.

See conversions inside your full retirement plan

Tesserae models conversions against your real accounts — the RMDs they shrink, the conversion-ladder access they unlock before 59½, and the ending balance with and without them. Privacy-first: you enter your own numbers, and we never touch your bank login.

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