The 2026 tax brackets offer a wide 24% bracket reaching $403,550 for married filers — creating a favorable window for Roth conversions before RMDs begin at age 73
A multi-year conversion ladder at 22-24% typically beats both aggressive one-year conversions and doing nothing, by balancing tax efficiency with IRMAA avoidance
Hidden costs including Medicare IRMAA surcharges, state income taxes, the pro-rata rule, and the itemized deduction cap can add 5-15 percentage points to the effective conversion rate
The best conversion years are low-income years between retirement and age 73 — especially the gap between stopping work and starting Social Security
How a Roth Conversion Works
A Roth conversion moves money from a pre-tax retirement account — traditional IRA, SEP IRA, SIMPLE IRA, or 401(k) — into a Roth IRA. The converted amount is added to your ordinary income for the year, taxed at your marginal rate, and then grows tax-free forever.
There's no income limit on conversions. Unlike Roth IRA contributions, which phase out for single filers above $165,000 and married filers above $246,000 in 2026, anyone can convert regardless of income. This is the so-called "backdoor" that high earners have used for years.
The deadline is December 31 — not the April tax filing deadline. A conversion you want counted for 2026 must be completed by December 31, 2026. And unlike contributions, conversions are irrevocable. You cannot undo a Roth conversion once it's done.
The key tradeoff: you're prepaying taxes at today's known rate to avoid paying at an unknown future rate. That bet pays off if your future tax rate would be higher than today's. It loses if your future rate would be lower.
The 2026 Tax Bracket Opportunity
The 2026 federal tax brackets create specific conversion windows worth understanding. For married couples filing jointly, the brackets are:
2026 Federal Tax Brackets (Married Filing Jointly)
Five Strategies That Actually Work
Hidden Costs That Change the Math
When a Roth Conversion Doesn't Make Sense
Running the Numbers: A Worked Example
Conversion Strategy Comparison
The 4-year ladder costs about $45,000 more upfront than the aggressive approach but avoids IRMAA surcharges and keeps them out of the 24% bracket entirely. The "no conversion" scenario assumes $40,000+ annual RMDs starting at 73, taxed at 22-24% for 20+ years.
Conclusion
Roth conversions are one of the few legal ways to control your future tax bill. The 2026 brackets, with the 24% threshold now reaching $403,550 for married couples, create a historically wide conversion window for middle-income retirees.
But the strategy only works if you run the numbers — including IRMAA, state taxes, the pro-rata rule, and the 5-year clock. The bracket-filling approach, spread across multiple years, beats both extremes: doing nothing (and facing taxable RMDs later) or converting everything at once (and spiking into higher brackets today). Start the math now. December 31 comes faster than you think.
Disclaimer: This content is for informational purposes only and does not constitute financial advice. Consult qualified professionals before making investment decisions.
Converting a traditional IRA or 401(k) to a Roth account means paying income tax now to enjoy tax-free withdrawals later. It sounds simple, but the math behind a smart Roth conversion is anything but. The right conversion in the right year can save tens of thousands in lifetime taxes. The wrong one just accelerates a tax bill for no benefit.
With the 2026 tax brackets now set — the seven-rate structure locked in by the One Big Beautiful Bill Act — and the fed funds rate sitting at 3.64%, the conversion calculus has shifted. The 24% bracket for married filers now stretches to $403,550, giving middle-income retirees and pre-retirees a wider lane to convert at favorable rates. But new wrinkles like the 35% itemized deduction cap and Medicare IRMAA surcharges mean the effective cost of a conversion can be higher than the headline tax rate suggests.
Here's how to figure out whether a Roth conversion makes sense for you in 2026, how much to convert, and the traps that catch people who don't run the numbers.
The standard deduction for married filers is $32,200, meaning a couple with no other income can convert roughly $68,600 and stay entirely in the 12% bracket ($100,800 minus $32,200). That's a 12-cent cost for every dollar that will never be taxed again.
The real sweet spot for most pre-retirees is the 22% and 24% brackets. A married couple with $80,000 in Social Security and pension income has about $323,550 of room in the 24% bracket ($403,550 minus $80,000 in taxable income). Converting enough to fill that bracket — but not spill into 32% — is the classic "bracket-filling" strategy.
For single filers, the math is tighter. The 24% bracket caps at $201,775, and the standard deduction is $16,100. A single retiree with $50,000 in income has roughly $135,675 of 24% bracket space before hitting 32%.
1. Bracket-filling in low-income years. The highest-value conversion years are when your income is temporarily low — between retirement and age 73 when required minimum distributions (RMDs) kick in, during a sabbatical, or in a year with large deductions. Fill the gap between your current taxable income and the top of your target bracket.
2. Multi-year conversion ladder. Don't convert a $500,000 IRA in one year — that pushes you into the 35% or 37% bracket. Spread it over five to seven years, converting $60,000-$100,000 annually to stay within the 22% or 24% bracket. The patience pays off: a $500,000 IRA converted over five years at 24% costs $120,000 in taxes. Converting all at once at a blended 32% costs $160,000.
3. Market-dip conversions. When your IRA drops 20% in a market correction, the conversion tax bill drops proportionally — but the recovery happens tax-free in the Roth. With the S&P 500 currently at $673.96 (SPY), near its 52-week high of $697.84, this isn't a dip-conversion moment. But keep this strategy ready for the next pullback.
4. Early retirement bridge. If you retire at 55 and don't collect Social Security until 67, you have 12 years of potentially low income. Converting aggressively during this window — especially in the first few years when you have the most control over taxable income — can dramatically reduce your lifetime tax burden.
5. Roth conversion before RMDs begin. Once RMDs start at age 73, they fill your lower brackets first. A retiree with $1 million in a traditional IRA faces roughly $40,000 in annual RMDs, pushing any conversion on top of that into higher brackets. Converting before 73 gives you more bracket room.
The headline tax bracket doesn't tell the whole story. Several "stealth taxes" can make a conversion more expensive than it looks.
Medicare IRMAA surcharges. Conversion income increases your modified adjusted gross income (MAGI), which determines Medicare Part B and Part D premiums. The kicker: there's a two-year lookback. A 2026 conversion affects your 2028 Medicare premiums. For a married couple, crossing the $403,000 MAGI threshold triggers an extra $4,320 per year in Part B premiums alone. Factor this into any conversion over $200,000.
The pro-rata rule. If you have both pre-tax and after-tax (non-deductible) money in your traditional IRAs, you can't cherry-pick which dollars to convert. The IRS treats all your traditional IRAs as one pool. If 10% of your total IRA balance is after-tax contributions, then 10% of any conversion is tax-free and 90% is taxable. The workaround: roll pre-tax IRA money into a 401(k) first, leaving only after-tax money in the IRA.
Itemized deduction cap. The One Big Beautiful Bill Act introduced a 35% cap on the value of itemized deductions for high earners in 2026. If you're itemizing and converting a large amount, the deduction cap effectively raises your marginal rate on the conversion amount.
State taxes. Conversion income is taxable in most states. In California (13.3% top rate) or New York (10.9%), a 24% federal conversion becomes a 37%+ combined rate. Some retirees time conversions to years when they reside in no-income-tax states like Florida or Texas.
Net Investment Income Tax. Conversion income itself isn't subject to the 3.8% NIIT, but it raises your AGI, which can push investment income over the $250,000 threshold for married filers, triggering the surtax on capital gains and dividends you'd otherwise keep.
Not every situation favors conversion. Skip it if:
You're already in a high bracket and expect lower retirement income. A 35% earner who'll retire into the 22% bracket is paying 13 percentage points more than necessary. Wait.
You need the IRA money to pay the tax. Paying conversion taxes from the IRA itself defeats the purpose — you lose the tax-free growth on those dollars and may owe a 10% early withdrawal penalty if you're under 59½.
You're within two years of Medicare enrollment. The IRMAA lookback means a large conversion at age 63 will spike your Medicare premiums at 65. Plan conversions before age 63 or after premiums have already been set.
Your estate plan favors charity. If you plan to leave your IRA to a charity through a qualified charitable distribution, the charity pays no tax on the withdrawal. Converting to a Roth first means you paid taxes the charity never would have owed.
The 5-year rule creates a timing problem. Each conversion has its own 5-year clock before earnings can be withdrawn tax-free (the converted principal is always accessible). If you're 60 and converting, the 5-year rule won't matter — you'll be past 59½ and past the 5-year window. But if you're 50 and need the money before 59½, converted amounts withdrawn within 5 years face a 10% penalty.
Meet Sarah and Tom, both 62, married filing jointly. Tom just retired; Sarah earns $70,000. Their traditional IRAs total $800,000. They want to convert as much as possible before RMDs start at 73.
2026 income before conversion:
Sarah's salary: $70,000
Interest and dividends: $12,000
Total: $82,000
Minus standard deduction: -$32,200
Taxable income: $49,800
They're in the 12% bracket ($49,800 is below the $100,800 threshold for MFJ). They have room to convert:
$51,000 to fill the 12% bracket (tax: $6,120)
$110,600 more to fill the 22% bracket ($100,800 to $211,400 — tax: $24,332)
$192,150 more to fill the 24% bracket ($211,400 to $403,550 — tax: $46,116)
Total conversion: $353,750 at a blended federal rate of roughly 21.6% ($76,568 in tax).
That's aggressive — and it would trigger IRMAA surcharges in 2028. A more measured approach: convert $161,600 to fill through the 22% bracket, costing $30,452 in federal tax. Repeat for three to four years as Sarah winds down her career. Over four years, they convert $640,000 at an average 19% rate instead of paying 24%+ on RMDs later.