Updated October 2026
How much should you convert to a Roth? Enough to “fill up” your current tax bracket without spilling into the next one — or past the nearest Medicare (IRMAA) income cliff, whichever comes first. For most retirees in the gap years before RMDs, that’s a slice sized each year, not one giant conversion that spikes your tax bill and your Medicare premiums.
Wait — didn’t I need to convert before 2026?
That was the old advice, and it had a shelf life. For years, planners warned that the 2017 tax cuts would “sunset” after 2025 and rates would jump, so you’d better convert while brackets were cheap.
Then the One Big Beautiful Bill Act (signed July 4, 2025) made the seven brackets — 10% through 37% — permanent. The top rate stayed at 37% instead of snapping back to 39.6%.
So the ticking-clock reason to convert is gone. Here’s the part most people miss: that doesn’t make conversions pointless — it just changes the question from “how fast?” to “how much?” The deadline died. The math didn’t.
Why convert at all if rates aren’t going up?
Because the rate Congress sets isn’t the rate you’ll actually pay in retirement. Four forces can quietly shove your future self into a higher bracket than you’re in today:
- RMDs. Required minimum distributions start at 73 (75 if you were born in 1960 or later). A seven-figure IRA can force out six-figure withdrawals you don’t even need.
- The widow’s penalty. When one spouse dies, the survivor usually files single — on roughly the same income but with brackets about half as wide. (More on that in our guide to the widow’s penalty tax.)
- IRMAA and the Social Security tax torpedo. Higher income means Medicare surcharges and more of your Social Security taxed — every single year.
- The 10-year rule. Heirs who inherit your traditional IRA must drain it within 10 years, often during their peak earning years at their highest rates.
A Roth conversion lets you pay tax now, on your terms, to defuse all four later. The trick is paying at a low rate — which is exactly what bracket-filling is built to do.
What does “filling up the bracket” actually mean?
Tax brackets are marginal: you only pay the higher rate on the dollars that land inside that bracket. “Filling up” means converting just enough to reach the top edge of your current bracket — and then stopping before the next, pricier dollar.
Here’s where the 2026 brackets break for a married couple filing jointly (taxable income, after the $32,200 standard deduction):
| 2026 rate | Married filing jointly | Single filer |
|---|---|---|
| 12% | up to $100,800 | up to $50,400 |
| 22% | $100,800 – $211,400 | $50,400 – $105,700 |
| 24% | $211,400 – $403,550 | $105,700 – $201,775 |
| 32% | $403,550 – $512,450 | $201,775 – $256,225 |
Say a 66-year-old couple has $90,000 of taxable income before any conversion. The 22% bracket runs all the way up to $211,400. That’s about $121,000 of “room” they could convert and still pay no more than 22% on the converted dollars.
Compare that to the alternative. If those same dollars get forced out as RMDs at 73 — stacked on Social Security and a pension — they could land in the 24% or 32% bracket. Paying 22% today to dodge 32% tomorrow is the entire game.
The ceiling most people forget: IRMAA
Here’s the counterintuitive part. For a lot of couples, the tax bracket isn’t the first wall you hit — the Medicare cliff is.
In 2026, the first IRMAA surcharge tier for a married couple kicks in at $218,000 of MAGI (about $109,000 single). Trip over that line by one dollar and your Medicare Part B and Part D premiums jump — for the whole year. And IRMAA uses a two-year lookback, so your 2026 income sets your 2028 premiums.
Notice the squeeze: the 22% bracket tops out at $211,400 of taxable income, and the IRMAA cliff sits at $218,000 of MAGI. Those are close enough that a big conversion can blow through both at once. That’s why the honest ceiling is “the top of your bracket or the next IRMAA tier, whichever comes first” — and why it’s smart to leave a cushion. Our full breakdown of the 2026 IRMAA brackets walks through the exact tiers.
One big conversion or spread over several years?
Spread, almost always. Doing it in slices keeps each year’s income low enough to stay in a cheap bracket and under the IRMAA cliff. One jumbo conversion does the opposite — it stacks all the income into a single year and pays the top rate on the overflow.
| Spread: ~$80k/yr for 5 yrs | Lump: $400k in one year | |
|---|---|---|
| Top bracket touched | Stays in 22–24% | Spills into 32% |
| IRMAA surcharge | Avoidable with planning | Almost certain |
| Social Security taxation | Managed year to year | Maxed in the big year |
| Flexibility if life changes | High — adjust each year | None — it’s irreversible |
That last row matters. Since 2018, you cannot undo (recharacterize) a conversion. Once it’s done, it’s done — so sizing it right the first time is the whole ballgame.
When are the best years to convert?
The sweet spot is the “gap years” — after you stop working but before RMDs and (ideally) before you claim Social Security. Income is temporarily low, brackets are temporarily empty, and you can fill them cheaply. This is the same window that makes a plan to reduce taxes on RMDs so effective, and it closes the moment RMDs begin.
One wrinkle for 2026: there’s a temporary senior deduction of up to $6,000 per person age 65+ ($12,000 for a couple) running 2025 through 2028. It phases out above $75,000 of MAGI (single) or $150,000 (joint) and disappears entirely at $175,000/$250,000. A large conversion can shrink or erase it — one more reason to go in slices, not all at once.
Who should think twice before converting?
Conversions aren’t free money, and they’re not for everyone. The tax is due in the year you convert, so you want outside cash to pay it — using IRA money to cover the bill defeats the purpose and can trigger a penalty if you’re under 59½. (The clock on accessing converted dollars has its own trap; see the Roth conversion 5-year rule.)
Think hard if your time horizon is short, if you have no cash outside the IRA to pay the tax, or if you’re already in — and expect to stay in — the same bracket you’d convert at. In those cases, the “pay now to save later” trade may not pay off.
Frequently asked questions
How much should I convert to a Roth each year?
Enough to reach the top of your current bracket (often the 22% or 24% band) without crossing into the next one or past the nearest IRMAA threshold. The dollar amount is simply that ceiling minus your other taxable income for the year.
Is there still a deadline to convert before taxes go up?
No. OBBBA made the 10%–37% brackets permanent in 2025, so the old “convert before the 2026 sunset” urgency is gone. The reason to convert now is to beat your own future RMD- and survivor-driven rate, not a legislated hike.
Does a Roth conversion count toward the IRMAA income limit?
Yes. Converted dollars raise your MAGI, which is exactly what IRMAA measures — so a conversion can push you over a Medicare surcharge cliff even though the money never left your control.
Can I undo a Roth conversion if I convert too much?
No. Recharacterizing a conversion has been off the table since 2018. That irreversibility is the single best argument for converting in measured annual slices.
Do Roth conversions reduce my RMDs?
Yes. Every dollar you move out of a traditional IRA is a dollar that won’t be subject to a future RMD — and Roth IRAs have no RMDs during your lifetime at all.
The bottom line
The deadline everyone worried about quietly expired, but the opportunity didn’t. The smartest conversions aren’t about racing a calendar — they’re about sizing each year’s slice to fill a cheap bracket, dodge the IRMAA cliff, and quietly shrink the tax bill your future self (or your spouse, or your kids) would otherwise inherit.
How much you should convert depends on your income, your Social Security timing, your Medicare bracket, and how your whole plan fits together — which is exactly the kind of thing worth mapping out before you pull the trigger. If you’d like a clear look at where your bracket-filling room actually is, a quick Tax-Free Wealth Secrets review is a low-pressure place to start.
This article is for educational purposes only and is not tax, legal, or financial advice. Roth conversions have real tradeoffs — the tax is owed in the year you convert, conversions can’t be reversed, and the right move depends on your personal situation. No outcome is guaranteed. Please consult a qualified advisor or tax professional before acting. Figures reflect 2026 IRS inflation adjustments and the One Big Beautiful Bill Act.
About the author
Matt Selph helps pre-retirees build tax-efficient, protected retirement income as the founder of Straight Answer Wealth Group. He writes about the strategies that actually move the needle — minus the hype. Connect on LinkedIn.
Sources: IRS, Roth IRAs; IRS, Required Minimum Distributions (RMDs) FAQs.
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