Should you do a Roth conversion, and how much?
Enter your numbers and I’ll work out how much to convert and when — including what it costs with federal and state taxes, a hidden tax effect on Social Security benefits, Medicare exposure, and the odds you’ll live long enough to benefit.
Your traditional IRA holds money the IRS hasn’t taxed yet — deferred, not exempt. Withdrawals generally become required and taxable starting at age 73 (75 if you were born in 1960 or later).
EXAMPLE
$380K IRA Converted Gradually
Traditional IRA
Tax owed on every withdrawal in retirement — and it compounds over time
VS
After Converting
More take-home — grows tax-free from here on
Converting saves ~$38K in total taxes vs keeping traditional (on this $380K IRA)
Pays today's known tax rate — more take-home, no required withdrawals from the Roth
Full-retirement totals from a multi-year conversion — the real payoff depends on future rates, returns, and lifespan matching these assumptions.
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Last year's tax return is your best starting point — adjust if your income or tax situation has changed significantly this year
2
See the true all-in cost — including the often-missed hidden tax on Social Security
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Use the Bottom Line as a starting point with your advisor
Do I need a Roth account already?
No. If you don't have one, the conversion creates it. The company holding your IRA (Fidelity, Vanguard, Schwab, etc.) handles this automatically when you convert.
Is there an income limit?
No — not since 2010. Anyone can convert regardless of income. You owe regular income tax on the converted amount — there's no earning cap.
Do I have to convert everything at once?
Not at all. You can convert any dollar amount. Converting a smaller amount to stay within your current tax bracket is one of the most common strategies.
Is there a penalty for converting?
No early withdrawal penalty on conversions, even before age 59½. You owe regular income tax on the converted amount — and depending on your situation, that can also mean higher Social Security taxability, Medicare premiums, or net investment income tax. Your breakdown below shows exactly what applies to you.
Is there a deadline each year?
Yes — December 31 of the tax year. Conversions processed by year-end count for that tax year. January 1st starts a new window.
When do I pay the tax?
When you file your return — not immediately. For smaller conversions, your regular withholding may already cover the bill. The larger the conversion, the more likely estimated taxes are due by January 15th to avoid an underpayment penalty. Your tax software will calculate exactly what you owe and when.
What does this tool model — and what does it simplify?
Modeled, from primary sources: 2026 federal brackets and standard deductions (IRS Rev. Proc. 2025-32), long-term capital gains and qualified dividend brackets (same source) stacked correctly on top of ordinary income, the 2025–2028 senior deduction including its phase-out and its exclusion for married-filing-separately filers (One Big Beautiful Bill Act), Social Security taxability (IRS Pub 915 worksheet), Medicare Income-Related Monthly Adjustment Amount (IRMAA) premium tiers for all filing statuses (official CMS 2026 rates), Required Minimum Distribution divisors (IRS Pub 590-B), and survival odds (SSA 2023 Period Life Table, exact figures).
Simplified, on purpose: Married-filing-separately Social Security taxability assumes you lived with your spouse during the year (the harsher, more common case — filers who lived apart all year get milder treatment this tool doesn't model). The multi-year plan holds income flat within each phase, including the assumption that today's investment income continues unchanged. Survival modeling ends at age 100. See "What This Calculator Doesn't Model" below for state and capital-gains caveats. When simplifying, this tool errs toward overstating your tax, not hiding it.
Simplified, on purpose: Married-filing-separately Social Security taxability assumes you lived with your spouse during the year (the harsher, more common case — filers who lived apart all year get milder treatment this tool doesn't model). The multi-year plan holds income flat within each phase, including the assumption that today's investment income continues unchanged. Survival modeling ends at age 100. See "What This Calculator Doesn't Model" below for state and capital-gains caveats. When simplifying, this tool errs toward overstating your tax, not hiding it.
Ready to see your own numbers?
Fill in what you know below — results update instantly.
EXAMPLE
About you
Income & accounts
How much
Medicare & assumptions
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About you
In plain English: Most married couples file "jointly," which usually means lower taxes. "Separately" is uncommon and often more expensive — especially for Medicare. "Single" is for unmarried filers; "Head of Household" applies to some single parents.
New for 2026: A new law gives people 65+ an extra $6,000 tax deduction per qualifying person, on top of the regular standard deduction. This can meaningfully reduce the tax cost of a conversion. Phases out above $75K (single) or $150K (joint). Not available if married filing separately — the law requires a joint return, so this selection has no effect if you file separately.
Optional, but affects your own numbers — used only for the survival-probability estimate (skip it and you get a reasonable default; answer it and your own odds are accurate)
Why this matters: State income taxes can materially change the cost of a Roth conversion. Some states also exempt IRA withdrawals in retirement — meaning you’d pay state tax on the conversion today but nothing when you withdraw later, which affects the comparison. Selecting your state adds these numbers automatically.
Planning to move before you convert?
Shows what the same conversion would cost if you wait until you’re a resident of this state instead — using your same age, income, and conversion amount. See the full breakdown below for the comparison.
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Income & accounts
Quick: Add lines 1z (wages), 2b (taxable interest), 3b (dividends), 7a (capital gains), and 8 (other income from Schedule 1) from your most recent federal return — rough estimates are fine. For more precision: use 3b minus 3a here and move line 3a (qualified dividends) and any long-term gains from Schedule D to the Qualified Dividends & Long-Term Capital Gains field in the optional section below, since those are taxed at lower preferential rates. Enter pension/IRA income (lines 4b/5b) in the field below — some states shelter it differently. Do NOT include Social Security (line 6b) here — it goes in its own field so the tool can model how converting makes more of it taxable.
What to include: A pension, annuity, or IRA/401(k) distributions you’re already receiving this year — not the conversion itself. Several states, including Michigan, shelter this specific kind of income from state tax up to a cap, but that cap doesn’t apply to wages. Splitting this out from the field above means the state-tax number reflects the real cap, instead of assuming your whole income competes for it. Leave at $0 if you’re still working and not yet drawing a pension or other retirement account. On your most recent federal return, this is lines 4b (IRA/401(k) distributions, taxable amount) and 5b (pensions and annuities, taxable amount). If line 4b includes a prior-year Roth conversion, subtract that amount — this field is for ongoing distributions only.
Not sure? Enter $0 — this only matters if you’re already receiving pension or retirement-account income separate from this year’s conversion
Why this field changes everything: Social Security benefits become partly taxable when your income reaches certain thresholds. A Roth conversion can push more of your SS into taxable territory — a hidden extra cost called the Social Security tax effect. At worst, each $1 converted triggers 85¢ more of SS taxation, pushing your real tax rate to ~40% even in the 22% bracket. Enter $0 if you do not receive SS yet. Use line 6a from your most recent federal return — your total benefit before any taxability calculation. Do not use line 6b (the taxable amount); the tool calculates the taxable portion itself.
Enter your total annual SS benefit, or $0 if not yet receiving
Enter $0 if you do not have one yet
Brokerage & investment income
What is this field? Qualified dividends (1099-DIV box 1b, or line 3a on your return) and net long-term capital gains (Schedule D, line 15) — these get the federal preferential rate (0%, 15%, or 20%) instead of your ordinary bracket rate, and this tool models that correctly, stacking them on top of your other income the way the IRS actually calculates it. A Roth conversion is ordinary income that stacks underneath this, so converting can push some of this income into a higher preferential-rate bracket — this tool accounts for that too. This income still counts toward Medicare IRMAA, Social Security taxation, and the 3.8% Net Investment Income Tax (NIIT) surcharge, just not your ordinary federal bracket. Enter $0 if this doesn’t apply to you.
Mutual funds, ETFs, and index funds report this on your 1099-DIV, Box 1b. Enter $0 if you don’t have a taxable brokerage account. This affects your Social Security taxability calculation.
What is this field? Interest, non-qualified dividends, short-term capital gains, and rental income — enter your annual total here. This tool taxes it at your ordinary income rate and includes it in the income that determines your tax bracket, Social Security taxation, and Medicare IRMAA tier, the same as wages or pension income. It also adds the 3.8% federal Net Investment Income Tax (NIIT) surcharge once your total income tops $200,000 (single) or $250,000 (married) — a Roth conversion counts as income and can push you over that threshold. Have qualified dividends or long-term capital gains? Those get a lower preferential rate (0/15/20%) — enter them in the field above instead, not here. If you filed Form 8960 last year, that’s the cleanest starting point — it already categorizes each type of NII. Otherwise, on a 1099-DIV, box 1a (ordinary dividends) already includes box 1b (qualified dividends) as a subset — put only the non-qualified portion (1a minus 1b) here to avoid double-counting. Enter $0 if this doesn’t apply to you.
Non-qualified dividends, interest (savings, bonds, CDs), rent, or short-term gains. Enter $0 if none of these apply.
IRA basis (most people: $0)
Have you ever contributed already-taxed money to a traditional IRA? If so, that amount is called your "basis." It matters because the IRS requires every conversion to be a proportional mix of taxed and untaxed money — you can’t cherry-pick just the pre-tax portion. The already-taxed share converts tax-free. If this applies to you, the number lives on IRS Form 8606, line 14. Most people enter $0 — the vast majority of IRA money is pre-tax.
Only applies if you’ve made non-deductible IRA contributions. Check IRS Form 8606, line 14.
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How much are you converting?
What to enter: Add up all your pre-tax retirement accounts — traditional IRAs, 401(k)s, 403(b)s, SEP-IRAs. Don’t have a statement handy? A rough estimate is fine for planning purposes. Every dollar here will eventually be taxed when withdrawn.
Pick a threshold as your starting point:
How much is right? It depends on your bracket, Medicare thresholds, and how much of your Social Security is currently taxable. Your results show all three common stopping points. There’s no income limit on conversions — anyone can convert in any year.
Your numbers are saved here automatically and will be waiting when you come back. Clicking Clear removes this saved copy too.
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Medicare & assumptions
The hidden two-year trap: Medicare charges higher premiums to people with higher incomes — called IRMAA. It’s based on your income from 2 years ago. A large Roth conversion in 2026 can raise your Medicare bill in 2028. This is one of the most commonly missed costs of converting.
What counts as income for Medicare? Medicare adds up all your income from all sources — wages, IRA withdrawals, taxable Social Security, dividends, and capital gains. A Roth conversion counts as income dollar-for-dollar, which is why large conversions can push you into a higher premium tier.
What counts as income for Medicare? Medicare adds up all your income from all sources — wages, IRA withdrawals, taxable Social Security, dividends, and capital gains. A Roth conversion counts as income dollar-for-dollar, which is why large conversions can push you into a higher premium tier.
7%
What to use? Historically ~7% after inflation for a diversified stock portfolio. A balanced mix of stocks and bonds might average 5–6%. Try sliding it to see how sensitive your results are.
Federal only — I add your state rate automatically. Enter your expected federal bracket rate on IRA withdrawals. Select your state above and I’ll fold the state rate in automatically so the comparison is apples-to-apples. Use the estimator below if you are unsure.
Not sure what rate to enter? Calculate it here ↓
Enter your expected retirement income sources and I’ll compute the marginal federal rate on your IRA withdrawals — including how conversions can trigger extra tax on Social Security benefits.
SS and pension start filled in from what you entered above — change them here only if you expect different amounts by the time you retire. Keep continued work or consulting income in "Wages or other" — a few states, including Michigan, shelter pension income differently than wages. If your income above includes dividends, interest, or rental income that continues in retirement, enter that portion in "Wages or other" as well.
This matters more than people expect: Paying from outside savings puts the full converted amount into the Roth tax-free. Paying from inside means less money enters the Roth — you’d be giving up tax-advantaged growth on the tax payment itself.