Calculate the federal + state tax cost of converting Traditional IRA to Roth in 2026. See break-even age, bracket impact, and 5-year rule timing.
A Roth IRA conversion moves money from a pre-tax traditional IRA (or 401(k)) into a Roth IRA, and the converted amount is added to your ordinary income for the year. At the 2026 federal brackets, converting $50,000 while earning a $90,000 salary pushes you from the 22% bracket into the 24% bracket — meaning roughly $11,400 in federal tax on the conversion alone, plus any state income tax. The exact number depends on your filing status, current taxable income, the conversion amount, and whether you pay the tax from outside funds or withhold it from the conversion itself (which is almost always a mistake under age 59½).
Use the calculator below to model the marginal cost of a 2026 conversion before you pull the trigger. Most people who run the numbers discover that converting in chunks across 3–5 lower-income years beats a single lump conversion by 15–30% in lifetime tax.
By Ziv Shay · Last updated May 2026
Every dollar you convert is treated as ordinary income on Form 1040, line 4b. It stacks on top of your wages, self-employment income, interest, and short-term gains. Here are the 2026 federal brackets you need:
Standard deduction for 2026: $15,000 single, $30,000 married filing jointly. Add the $2,000 extra deduction if you're over 65.
To calculate your conversion tax: take your projected adjusted gross income, add the conversion amount, subtract your standard or itemized deduction, then apply the brackets to the resulting taxable income. Subtract what you would have owed without the conversion — the difference is your conversion tax bill.
Sarah and Mike file jointly. Mike earns $120,000, Sarah is a stay-at-home parent. They want to convert $100,000 from Mike's old 401(k) (rolled to a traditional IRA) into a Roth IRA.
Without conversion:
With $100,000 conversion:
Conversion cost: $21,415 federal — an effective 21.4% rate on the $100,000 converted. Add a state like California at ~9.3% on the marginal income and the all-in cost climbs to roughly $30,700.
If they instead converted $50,000 in 2026 and another $50,000 in 2027 (assuming similar income), they'd stay almost entirely within the 22% bracket on both conversions, saving approximately $2,800 in federal tax over the two-year sequence. That's the chunking advantage in concrete dollars.
One of the most expensive mistakes people make: withholding 24% from the conversion itself to cover the tax. If you're under 59½, that withheld amount is treated as a distribution, which means a 10% early withdrawal penalty plus the loss of all future tax-free growth on those dollars. On a $100,000 conversion with $24,000 withheld, you forfeit roughly $2,400 in penalty and surrender ~$160,000 of future tax-free growth (assuming 30 years at 7% real return).
The right move is to pay the federal and state tax from a taxable brokerage or savings account, so the entire $100,000 lands in the Roth and starts compounding tax-free immediately. If you don't have outside cash, the conversion is probably not the right move this year.
If your taxable income drops below $50,000 single or $100,000 MFJ, you can fill the 12% bracket with conversions at a permanent discount versus the 22%+ rate you'll likely face in retirement.
Large business losses, charitable contributions through a donor-advised fund, or a major medical event can create deduction headroom. A conversion mops up that headroom productively instead of letting it expire.
The TCJA brackets are scheduled to revert at the end of 2025 — though Congress extended most provisions through 2026, the 2027+ environment remains uncertain. Locking in current rates via conversion is a cheap insurance policy.
Under the SECURE Act, non-spouse beneficiaries must drain inherited IRAs within 10 years. Converting to a Roth shifts the tax burden to you (likely at a lower rate) and hands heirs a tax-free asset they can grow for a decade.
Required minimum distributions begin at age 73. Conversions in your 60s can shrink the traditional IRA balance enough to keep RMDs from pushing you into a higher bracket or triggering IRMAA Medicare surcharges.
IRMAA Medicare surcharges. If you're 63 or older, a large conversion can spike your modified AGI and trigger Medicare Part B and D premium surcharges two years later. The 2026 IRMAA threshold begins at $106,000 single / $212,000 MFJ, with surcharges ranging from $74 to $443 per month per person.
Net Investment Income Tax. Conversions don't count as investment income, but they raise your MAGI and can push other investment income (dividends, interest, capital gains) above the $200,000 single / $250,000 MFJ NIIT threshold, adding 3.8% on that income.
Social Security taxation. If you're already collecting Social Security, the conversion can push up to 85% of your benefits into the taxable bucket, an effect sometimes called the "tax torpedo."
State taxes. States with no income tax (TX, FL, TN, NV, WA, SD, WY, AK, NH) make conversions much cheaper. High-tax states (CA, NY, NJ, OR) can add 6–13% on top of federal. If you're planning a move to a no-tax state, wait to convert until after you establish residency.
If you have any pre-tax money in any traditional, SEP, or SIMPLE IRA across all your accounts on December 31 of the conversion year, the IRS forces you to convert proportionally. Example: you have $90,000 pre-tax in a rollover IRA and contribute $7,000 after-tax to a separate traditional IRA hoping to do a backdoor Roth. The IRS treats your IRAs as a single $97,000 pool — only ~7.2% ($504) of your $7,000 conversion is tax-free; the rest is taxable.
The fix: roll your pre-tax IRA into your current employer's 401(k) before December 31, isolating the after-tax contribution for a clean conversion. For more on this, see our guides on the backdoor Roth IRA calculator and mega backdoor Roth strategy.
Convert in January or February so the assets have an entire year of tax-free growth inside the Roth. But pay your estimated tax in Q4 (or via increased W-2 withholding late in the year) — that way you keep the cash earning interest in your savings account for 9–10 months. Use the IRS Form 1040-ES safe harbor: pay 100% (110% if AGI > $150k) of last year's tax liability to avoid underpayment penalties.
One nuance: the 5-year clock for tax-free Roth withdrawals on converted amounts starts January 1 of the conversion year. So a January 2026 conversion becomes accessible penalty-free in January 2031, regardless of age (though earnings still need 59½).
30s and 40s: Conversions rarely make sense unless you're in a low-income gap year. Your current marginal rate is likely close to your retirement rate, and you have decades of compounding ahead — pay the tax later.
50s: Start modeling. If you're a high earner planning early retirement, the gap years between retiring and Social Security/RMDs are golden conversion years. Build the Roth bucket now so you have tax diversification later.
60s pre-RMD: The peak conversion window. Use our retirement savings calculator and RMD calculator to project the size of your future RMDs. If they'll exceed your spending needs, convert aggressively in your 60s to drain the traditional balance.
70s+: Conversions still work but the runway is shorter. Focus on filling the 12% and 22% brackets each year and use Qualified Charitable Distributions to satisfy RMDs tax-free if you're charitably inclined.
No. The Tax Cuts and Jobs Act eliminated Roth recharacterizations in 2018. Once you convert, the tax bill is locked in. This is why running the calculator and confirming you have outside cash for taxes before converting is critical.
No annual limit. You can convert $1,000 or $1,000,000 — the only constraint is your willingness to pay the resulting tax. This is different from Roth IRA contributions, which are capped at $7,000 ($8,000 if 50+) for 2026.
No. The conversion amount is excluded from the income test for direct Roth contribution eligibility. You can convert $200,000 and still make a regular $7,000 Roth contribution if your non-conversion income is below the $161,000 single / $240,000 MFJ phase-out for 2026.
You owe tax on the value at the moment of conversion, regardless of what happens afterward. If you convert $100,000 and the account drops to $70,000 in March, you still owe tax on the full $100,000 in April. Since recharacterizations are no longer allowed, the only mitigation is to convert in smaller chunks or wait for a market dip and convert at lower valuations.
If your 401(k) plan allows in-plan Roth conversions, do it directly — this avoids the pro-rata rule entirely. If your plan doesn't, you can roll the 401(k) to a traditional IRA and then convert, but be aware this combines that money with any existing traditional IRA balances for pro-rata calculations going forward.
Disclaimer: This content is for educational purposes only and does not constitute financial, tax, or legal advice. Consult a qualified financial advisor or CPA before executing a Roth conversion — the dollar figures involved make professional review worth the fee.
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