Roth Conversion Tax Bracket Calculator: Fill Your Bracket, Not the IRS’ Coffers (2026)

A Roth conversion moves money from a traditional pre-tax IRA or 401(k) into a Roth IRA, and the tax bill lands on your current-year return at your current-year rates. Done right, the strategy is one of the most powerful retirement moves available: you convert dollars at 12% or 22% today to avoid paying 24% or 32% later, and everything the Roth earns from that day forward is tax-free forever. Done wrong, a single oversized conversion pushes you into a higher bracket, triggers the Medicare IRMAA surcharge two years out, and converts your cheapest dollars at your most expensive rates.

The whole strategy lives or dies on one number: bracket room — the distance between your taxable income and the ceiling of your current bracket. This page gives you a working Roth conversion tax bracket calculator built on the official 2026 federal brackets, runs three conversion strategies head-to-head (bracket-fill, even spread, and all-at-once), and answers the question most conversion guides never touch: if you stop converting at the bracket ceiling, how much tax do your heirs owe on what stays traditional — and what would a term life insurance policy that covers that bill cost per month?

How Roth Conversion Taxes Actually Work

When you convert, the amount you move is added on top of your taxable income for the year. If you file single with $60,000 of taxable income, you sit inside the 22% bracket, which in 2026 runs from $50,400 to $105,700. You can convert up to $45,700 — the calculator's default room — before a single dollar crosses the 24% line. That converted amount is taxed exactly like ordinary income: the first dollars fill the remainder of your 22% bracket, and every dollar past the ceiling is taxed at 24%, then 32%, then 35%, then 37%.

Three mechanical rules matter as much as the rates:

• Conversions have no required distributions. Roth IRAs are exempt from lifetime RMDs, so converting early eliminates the forced taxable income that RMDs create from age 73 (75 for those born in 1960 or later).
• The 10-year rule is why heirs care. Under the SECURE Act, most non-spouse beneficiaries must empty an inherited traditional IRA within 10 years, paying ordinary income tax on every withdrawal. A large pre-tax balance can shove an adult child into the top brackets during the drain years. Inherited Roth IRAs must also be emptied within 10 years for non-eligible beneficiaries, but the withdrawals are tax-free.
• You cannot undo a conversion. The recharacterization rule that once let investors reverse conversions was repealed in 2017 (TCJA). Every conversion is final.

The 2026 Federal Brackets the Calculator Uses

The calculator embeds the official 2026 inflation-adjusted brackets from IRS Revenue Procedure 2025-32, for single and married-filing-jointly filers:

Two cliff details the brackets don't advertise. First, the gap between brackets is not uniform: 22% sits 2 points under 24%, but 24% sits 8 points under 32% — the single biggest jump in the schedule. Filling your bracket to the ceiling is cheap; drifting one dollar past it into the 32% band on a big conversion is where conversions go wrong. Second, conversions stack on top of income that already fills lower brackets, so the calculator computes the marginal cost of each strategy as the change in total tax, not the average rate applied to the conversion.

What the Calculator Shows: Three Strategies Head-to-Head

The tool runs your balance through the same three strategies every conversion analysis should test — the "convert none, convert all, convert some" framework retirement planners use:

1. Bracket-fill. Each year, convert exactly the amount that fills your current bracket to its ceiling — the room the calculator displays up top. Repeat until the window closes. This is the classic low-bracket strategy, and it works best when your balance is small relative to the room you have across the window.
2. Even spread. Divide the balance evenly across the conversion years, even when that pushes past the ceiling. This is the strategy for large balances: it deliberately pays some higher-bracket tax in exchange for actually finishing the job within the window.
3. All at once. Convert everything in year one. Almost always the most expensive path — the calculator shows exactly how many bracket rungs a lump conversion climbs and what average rate it produces — but it is occasionally rational when a known future event (RMDs, the 10-year rule, a move to a high-tax state) would tax the balance even harder later.

At the default inputs — a $400,000 pre-tax balance, $60,000 of taxable income, single, a six-year window, 5% growth — the comparison is stark. Bracket-fill converts $274,200 at a 22.0% average rate but leaves $209,648 still traditional at the end of the window. Even spread converts the whole balance (roughly $453,000 after growth, because unconverted years keep compounding) at 22.8%. The all-at-once path converts everything at 30.5%, climbing three bracket rungs in a single year. Which strategy "wins" depends on what you're optimizing: bracket-fill wins on rate, even spread wins on completeness, and the heirs' tax bill on the remainder is the number that connects the two.

The Heirs' Tax Bill: Why Conversions Are Also a Life Insurance Decision

Here is the part of the conversion math that gets skipped in most guides. Suppose you follow the textbook advice — convert only up to your bracket ceiling every year — and die with a large traditional balance remaining. Your heirs don't get a tax holiday. Under the SECURE Act's 10-year rule, a non-spouse adult child must drain that inherited IRA within a decade, paying ordinary income tax at their rates, on their return, at their peak earning years. A $400,000 traditional remainder landing on a child earning $120,000 is taxed at 24% federal plus state — a five-figure bill due on a schedule they don't control.

The calculator sizes the problem and prices the fix. It multiplies whatever still stays traditional at window end under your winning strategy by your marginal rate (a proxy for the heirs' blended rate), rounds up to the nearest $25,000, and prices a level term policy on that face. At the defaults, the heirs' tax bill on the bracket-fill remainder is roughly $46,000 — and a $50,000 20-year term policy for a 58-year-old male standard class costs about $24 per month. For the price of one dinner out per month, your heirs receive the cash to pay the conversion-completion tax on their schedule, without selling investments or draining other accounts to do it.

Read that table again and notice the real insight: the bracket-fill strategy and the life insurance backstop are a package deal. You get the lowest average rate today, and a modest term policy hands your heirs the money to finish the conversion you didn't live to complete — taxed once, at your rate rather than theirs, through a premium you can afford. The alternative (even spread) finishes the job without insurance but pays 22.8% blended, including dollars pushed into the 24% bracket. Neither is "correct" — they're different allocations of the same tax budget.

Paying the Tax From Outside vs. Inside the IRA

The calculator has a funding toggle because this choice changes everything:

• Pay from outside savings. The full converted amount lands in the Roth, the tax comes from your bank account. This is the gold-standard method — Vanguard's retirement research frames it as the single biggest driver of whether a conversion adds wealth, because outside funding seeds the Roth with its full balance and preserves the IRA's remaining compounding.
• Pay from inside the IRA. You withdraw extra to cover the tax. The withdrawn slice is taxed but never converts, and if you're under 59½ the 10% early-distribution penalty stacks on top. The calculator models this explicitly: it grosses up the withdrawal so the net conversion still fills the bracket room, applies the penalty when your age qualifies, and shows how much smaller your ending Roth balance is. In the default scenario, inside funding cuts the final Roth balance by nearly half and adds roughly 5 points to the effective rate. Under 59½, inside funding is almost always a mistake.

When a Roth Conversion Backfires

The calculator's warning branch fires when your income already fills the 37% bracket — there is no cheap room, and every converted dollar costs your top marginal rate. But there are subtler traps it discloses in the assumptions:

• IRMAA. A conversion raises your modified adjusted gross income, and Medicare's income-related monthly adjustment amount looks back two years. A conversion that crosses an IRMAA threshold can raise Medicare Part B and D premiums for both spouses — the calculator doesn't model it, but the thresholds sit low enough ($109,000 single MAGI for the first tier in 2026) that early retirees hit them easily.
• The 59½ age floor. Conversions themselves are never penalized at any age, but paying the tax from inside the IRA before 59½ is. And the five-year rule applies to each conversion's earnings for early withdrawals.
• State tax. The calculator adds your state rate input to every marginal calculation. Moving states mid-strategy is legitimate planning — converting while a resident of a zero-tax state is one of the few genuinely free lunches left in the code.
• Bracket-fill with a shrunk balance. If your balance is small relative to the room across your window, bracket-fill finishes the job anyway and even-spread wins nothing — the calculator handles this crossover automatically rather than assuming spread always wins.

Who Should Use Which Strategy

How the Heirs' Backstop Compares to Converting Everything

The insurance-funded hybrid has one more property worth naming: it is reversible at every step. A conversion is final the year you make it — you cannot un-pay 30% tax if rates change, if you need long-term care, or if a financial shock makes the converted dollars worth less than you paid for them. The bracket-fill-plus-backstop strategy converts only what the cheap brackets can absorb, keeps the powder dry, and lets a $25-per-month policy carry the tail risk instead. If Congress changes the rules, you've lost only a few years of modest conversions, not a decade of 30-cent dollars. For households whose estate plan already includes estate tax insurance, the heirs' conversion backstop slots into the same logic: pay pennies for the optionality, convert only what's certainly cheap.

Assumptions and Limitations

• The calculator uses 2026 federal brackets from IRS Rev. Proc. 2025-32 for single and MFJ filers; state tax is a flat user input and does not model state-specific Roth or retirement-income exclusions.
• The standard deduction, itemized deductions, and credits are not modeled — the "taxable income" input is post-deduction by definition.
• IRMAA Medicare surcharges, net investment income tax, capital-gains stacking interactions, and the kiddie tax are outside the engine. A conversion large enough to cross IRMAA lines deserves a tax professional's review before execution.
• The heirs' tax bill uses your marginal rate as a proxy for the heirs' blended rate; an heir in a different bracket pays a different amount.
• Backstop premiums use level-premium term anchors interpolated from a 2026 market table shared across this site's calculators — an estimate, not a quote.
• Conversions from employer plans (401k) carry plan-level rules — in-plan Roth rollovers, after-tax subaccounts, and employer-match treatment differ from IRA conversions and are not modeled.

Frequently Asked Questions

How much can I convert without moving up a tax bracket?

For a single filer with $60,000 of taxable income in 2026, the answer is $45,700 — the distance to the $105,700 ceiling of the 22% bracket. The calculator computes this automatically for your income and filing status, and shows how the room changes at income levels $20K–$80K above and below yours so you can see the sensitivity. Married filers get roughly double the room at every bracket.

Is it better to convert everything at once or spread it out?

For almost everyone, spreading wins. The calculator's default scenario shows a lump conversion taxed at 30.5% average versus 22.0-22.8% for the spread strategies. A single-year conversion only makes sense in a genuinely low-income year — a business loss, a gap year, the first year of semi-retirement — when your brackets are temporarily bottom-tier.

Do Roth conversions count as income for IRMAA?

Yes. Conversion amounts flow into modified adjusted gross income, and Medicare's IRMAA determination uses MAGI from your tax return from two years prior. A conversion that pushes you past a 2026 IRMAA threshold ($109,000 single MAGI at the first tier) raises Part B and Part D premiums for both spouses two years out. Converters near Medicare age should model IRMAA explicitly with a tax professional — the calculator deliberately does not, and its assumptions section says so.

What happens to an inherited traditional IRA under the 10-year rule?

Most non-spouse beneficiaries — adult children primarily — must fully empty the inherited account within 10 years of death, paying ordinary income tax on each withdrawal at their own rates. There is no annual minimum in most cases, but the deadline is absolute, and a large balance drained late can stack on top of the heir's peak-earning-year income. This is exactly the exposure the calculator's heirs' tax card quantifies and the backstop policy covers.

Can life insurance really pay my heirs' conversion tax bill?

It hands them the cash to pay it. The calculator sizes the tax exposure on the traditional balance that remains under your strategy, rounds up to the nearest $25,000, and prices a level term policy on that face. The death benefit is income-tax-free to beneficiaries, arrives outside probate, and lands exactly when the 10-year clock is running. At typical sizes ($25K–$100K of coverage for a household in its late 50s), premiums run $15–$60 per month — a fraction of the tax bill itself.

Should I pay the conversion tax from savings or from the IRA?

From outside savings whenever possible. Paying from inside the IRA shrinks the amount that actually converts, and before age 59½ it adds a 10% penalty on the withdrawn tax money. The calculator's funding toggle shows the damage: in the default scenario, inside funding cuts the final Roth balance by roughly half versus outside funding and raises the effective rate about 5 points.

Do conversions make sense if I'm already retired and in a high bracket?

Often still yes, but the math is tighter. If RMDs will push you from 24% into 32% at age 73, converting at 24% today beats waiting. If your RMDs will stay inside your current bracket forever, conversions are neutral-to-negative. The calculator's high-income warning branch flags the case where no cheap room exists; partial conversions of whatever room remains, plus the heirs' backstop, remain available.

Key Takeaways

• Bracket room — the distance from your taxable income to your bracket's ceiling — is the single number that governs conversion sizing. In 2026, a $60K single filer has $45,700 of room; the calculator computes yours instantly.
• Bracket-fill (convert to the ceiling, stop) is the cheapest strategy per dollar; even-spread finishes large balances the cheap brackets can't absorb; all-at-once is almost always the most expensive path.
• The heirs' tax bill under the SECURE Act 10-year rule is the hidden cost of stopping at the ceiling — and a term policy sized to that bill costs $15–$60 per month at typical household sizes.
• Pay conversion taxes from outside savings whenever you can; inside funding before 59½ triggers the 10% penalty and shrinks what actually converts.
• Conversions are final (no recharacterization since 2017) — which is precisely why converting only the certainly-cheap brackets and insuring the remainder is the more robust plan.

Related Resources

• Inherited IRA Tax Calculator — the heirs' side of this page: SECURE Act windows, RMD schedules, and the exact tax bill your beneficiary inherits.
• Widow Survivor Income Phase Calculator — when a surviving spouse faces the MFJ-to-single bracket squeeze, conversions before the squeeze are the fix.
• Life Insurance Duration Calculator — how long a death benefit lasts against a monthly need, for survivors draining an inherited account.
• Financial Underwriting Capacity Calculator — how much coverage a carrier will issue at your income level, relevant for larger backstop policies.
• MYGA vs CD Calculator — where to park the savings funding your conversion taxes during the strategy years.

External references: IRS Publication 590-B (distributions from individual retirement arrangements, including conversion rules), IRS RMD rules, NAIC consumer resources, and AM Best carrier ratings for vetting the insurer behind any backstop policy.