A physician who saves diligently in tax-deferred accounts for 25 years retires with a specific problem: the money got in cheaply and is scheduled to come out expensively. A radiologist who maxed a , a 457(b), and backdoor contributions from age 35 can plausibly reach 62 with $3,000,000 to $5,000,000 in traditional accounts. Left untouched, that balance compounds until required minimum distributions begin at age 73 — or 75 if you were born in 1960 or later — and then the tax code starts forcing income onto your return whether you want it or not. Between your retirement date and that first RMD sits a window of deliberately low-income years, and what you do with those years is one of the highest-stakes tax decisions of your life.
The window: your gap years are the cheapest tax capacity you will ever own
The logic of the gap-years conversion strategy is simple once you see the shape of your lifetime tax rate. During your attending years, every marginal dollar you recognized was taxed at 32%, 35%, or 37%. After RMDs begin, a large traditional balance can force enough income to land you back in the 32% bracket — plus Medicare premium surcharges, plus the 85% inclusion tier on your Social Security benefits. But in the years between retirement and RMDs, your taxable income can collapse to nearly nothing: some interest, some dividends, maybe a small pension. Those years offer bracket space at 10%, 12%, 22%, and 24% that will otherwise expire unused.
A Roth conversion moves dollars from a to a , recognizing the converted amount as ordinary income today in exchange for tax-free growth and tax-free withdrawals afterward, with no RMDs on the Roth for the owner during life. The arithmetic of the window is asymmetric: converting at 22% or 24% money that would otherwise emerge at 32% or higher is a permanent, riskless spread — the only requirements are that you actually have low-income years and that you fill them deliberately. Under SECURE 2.0, the RMD age is 73 for those born 1951 through 1959 and 75 for those born in 1960 or later, so a physician retiring at 60 may hold a 13-to-15-year window. That is not a rounding error; it is an entire second career of tax planning.
Whether Roth or traditional dollars should have priority in the first place is the subject of the Roth versus traditional module; this article assumes the deferred balance already exists and asks what to do with it now.
Bracket filling: the method, worked with 2026 numbers
Bracket filling means converting exactly enough each year to bring taxable income to the top of a chosen bracket — no more, no less. For 2026, married filing jointly, the standard deduction is $32,200 and the relevant bracket ceilings are $99,600 for the 12% bracket, $211,400 for the 22% bracket, and $403,550 for the 24% bracket, per Rev. Proc. 2025-32.
Example calculation
Assumptions, stated explicitly: married couple, both retired physicians, ages 61 and 60, filing jointly for 2026. Baseline income of $80,000 (pension plus taxable interest and dividends). Standard deduction of $32,200. No state income tax modeled. All figures from Rev. Proc. 2025-32.
Baseline taxable income: $80,000 − $32,200 = $47,800
Room to the top of the 22% bracket: $211,400 − $47,800 = $163,600 of conversion capacity Tax on that conversion: 12% band ($47,800 → $99,600): $51,800 × 12% = $6,216 22% band ($99,600 → $211,400): $111,800 × 22% = $24,596 Total: $30,812 on $163,600 converted = 18.8% effective rate
Room to the top of the 24% bracket instead: $403,550 − $47,800 = $355,750 of capacity Additional tax on the extra $192,150 at 24% = $46,116 Total: $76,928 on $355,750 converted = 21.6% effective rate
Every converted dollar in this example escapes a future forced distribution that could plausibly land at 32% or above once RMDs, Social Security, and survivor filing status stack up.
Notice the shape of the result: even the aggressive 24%-bracket fill carries an effective rate near 21.6%, roughly ten points below the 32% this couple paid on their last attending dollars. The spread is the strategy.
The constraint stack: three tripwires that override the bracket math
Bracket ceilings are not the binding constraint for most physician retirees. Three other systems key off your income, and each one can turn a well-intentioned conversion into an expensive mistake.
IRMAA, with its two-year lookback. Medicare premiums are means-tested against from two years prior: your 2026 conversion sets your 2028 premiums. For 2026, the standard Part B premium is $202.90 per month, and the first IRMAA tier begins at $218,000 of MAGI for joint filers, lifting Part B to $284.10 per person. These are cliffs, not phase-ins — one dollar of MAGI over the threshold triggers the full surcharge for both spouses for a full year. In the worked example above, filling the 22% bracket produces MAGI of roughly $243,600, which sails past the $218,000 threshold. A couple already on Medicare might instead cap the conversion at $138,000 to hold MAGI just under $218,000, accepting a smaller conversion to avoid roughly $1,900 per year in Part B surcharges alone, before Part D surcharges. A couple aged 61 and 60, however, will not file for Medicare until 65 — conversions executed more than two years before Medicare enrollment never appear in an IRMAA lookback at all. The window before age 63 is therefore doubly valuable.
Important
The IRMAA lookback means your conversion decisions echo forward two years, and the thresholds are cliffs. Before converting in any year in which either spouse will be 63 or older, model the premium consequence explicitly. A conversion that saves 8 points of bracket spread but triggers two years of dual-spouse IRMAA surcharges can be a net loss on amounts near the threshold.
The ACA cliff, for conversions before 65. If you retire before Medicare eligibility and buy marketplace coverage, your conversion income counts toward the MAGI that determines premium tax credits. The enhanced subsidies that temporarily removed the income ceiling expired on December 31, 2025, and for 2026 the original structure is back: premium tax credits vanish entirely above 400% of the federal poverty level. One dollar of conversion income over the cliff can cost a 60-year-old couple the whole subsidy — often $15,000 to $25,000 of annual premium support depending on age and region. For an early-retired physician on marketplace coverage, the effective marginal rate on the conversion dollar that crosses the cliff is measured in thousands of percent. Some households should convert nothing in ACA years and save the window for ages 65 through RMD age; others should abandon the subsidy deliberately in one big conversion year and defend it in the others. What rarely makes sense is drifting across the cliff by accident.
The 5-year conversion clocks. Under the ordering rules in Pub. 590-B, each conversion carries its own 5-year holding period beginning January 1 of the conversion year. Withdrawing converted principal before its clock matures triggers the 10% early-distribution penalty — but only if you are under 59½, because the penalty itself disappears at that age. Separately, tax-free treatment of Roth earnings requires both age 59½ and a 5-year clock that starts with your first-ever Roth contribution or conversion. For a physician converting at 60, the practical implications are mild: open a Roth now if you somehow never have, and treat the account as long-horizon money. For a physician executing a conversion ladder at 48 to fund early retirement, the clocks are load-bearing and each rung must be scheduled five years ahead of the spending it funds — the mechanics connect directly to the physician FIRE playbook.
| Constraint | 2026 trigger (MFJ) | Consequence | Who it binds |
|---|---|---|---|
| 22% bracket ceiling | $211,400 taxable income | Marginal rate steps to 24% | Everyone converting |
| 24% bracket ceiling | $403,550 taxable income | Marginal rate steps to 32% | Large-balance converters |
| IRMAA tier 1 | $218,000 MAGI (cliff) | Part B $202.90 → $284.10 each, two years later | Either spouse 63+ |
| ACA subsidy cliff | 400% FPL MAGI (cliff) | Entire premium tax credit lost | Marketplace coverage before 65 |
| Conversion 5-year clock | Per-conversion, from Jan 1 | 10% penalty on early withdrawal of converted principal | Converters under 59½ |
A conversion schedule, not a conversion event
The single most common execution error is treating conversion as a one-time decision. The window is a multi-year asset, and the optimization is a schedule: how much, in which years, against which constraints. A physician retiring at 60 with a January 1960 birthday holds fifteen calendar years before RMDs at 75. The schedule might look like: modest conversions inside the ACA constraint from 60 to 64, then larger fills from 65 to 74 — remembering that the lookback means conversions from age 63 onward already feed the IRMAA calculation for premiums beginning at 65, so the truly unconstrained years end earlier than they appear to. Or, if the couple claims Social Security at 70, the schedule front-loads harder into ages 65 through 69, because benefit income will consume bracket space afterward.
Sequencing conversions against Social Security timing, taxable-account drawdown, and account ordering is exactly the machinery covered in the drawdown sequencing module, and the size of the portfolio this all serves is stress-tested in the safe-withdrawal evidence article.
Key insight
Do not optimize any single year; optimize the area under the curve. A schedule of eight moderate conversions at an 18% to 22% effective rate nearly always beats two heroic conversions at 24% plus IRMAA damage, and it also spreads the risk of legislative change, market drawdowns (converting after a 25% market decline converts more shares per tax dollar), and estimation error in your own future income.
When not to convert: charity and basis change the answer
Conversion is not a universal good, and two situations argue for leaving traditional dollars alone.
First, charitable intent. Beginning at age 70½, qualified charitable distributions allow direct IRA-to-charity transfers — up to $111,000 per person in 2026 — that count toward RMDs and never touch your return. A physician who expects to give $20,000 to $50,000 per year in retirement holds a standing pipeline that drains the traditional balance at a 0% rate. Converting those dollars first at 22% and donating cash later is strictly worse. Estimate your lifetime giving, subtract it from the traditional balance, and size the conversion schedule against what remains.
Second, the terminal tax rates of heirs — and the estate itself. Traditional IRA dollars left to a low-bracket heir, or consumed in late-life medical and long-term-care years when deductions run high, may exit at rates below your conversion rate. Conversion buys certainty; it does not always buy savings. Appreciated taxable assets, by contrast, receive a basis step-up at death that conversions have nothing to do with — do not liquidate appreciated taxable holdings to pay conversion tax late in life without pricing the foregone step-up.
Quick takeaway
The gap-years conversion strategy in one paragraph: between retirement and RMD age 73 or 75, fill low brackets deliberately with Roth conversions — the 2026 MFJ arithmetic supports effective rates near 18% to 22% on six-figure annual conversions — while respecting the IRMAA cliff at $218,000 MAGI with its two-year lookback, the restored 400%-FPL ACA cliff before 65, and the per-conversion 5-year clocks if you are under 59½. Build a multi-year schedule, and carve out charitable dollars for QCDs before you size it.
Common questions
How much should I convert each year?
There is no universal number; there is a method. Start from your baseline taxable income, pick the constraint that binds first — a bracket ceiling, the $218,000 IRMAA threshold if either spouse is 63 or older, or the 400%-FPL ACA cliff if you hold marketplace coverage — and convert up to it, minus a safety buffer of $5,000 to $10,000 for late-arriving income such as fund distributions. Then repeat annually. The right answer changes every year with your income, the indexed thresholds, and market values.
Do I pay the conversion tax from the IRA or from taxable savings?
From taxable savings, almost always. Paying from the IRA shrinks the amount reaching the Roth, and if you are under 59½ the withheld portion is itself a penalized early distribution. A conversion funded with outside cash effectively stuffs extra value into the tax-free account. If you lack taxable cash to pay the tax, that is usually a signal to convert less this year, not to raid the IRA.
I am 58 and retired. Do the 5-year rules block me from touching converted money?
Each conversion you make now carries its own 5-year clock, and withdrawing that converted principal before the clock matures — while you are under 59½ — triggers the 10% penalty under the Pub. 590-B ordering rules. At 58, a conversion is locked until roughly 59½ anyway, at which point the penalty vanishes regardless of the clock. The earnings on your Roth need age 59½ plus a 5-year clock from your first Roth funding, so if you have held any Roth since before 2021, earnings are fully tax-free once you cross 59½.
Does converting make sense if I plan to leave everything to charity?
Generally no for the charitable portion. Dollars bound for charity exit a traditional IRA tax-free — through QCDs during life or a charitable beneficiary designation at death — so prepaying 22% to 24% on them destroys value. Size conversions against the balance you expect your household and non-charity heirs to actually spend.
What to do next
- Pull your most recent statements and total every traditional (pre-tax) balance across 401(k), , 457(b), and IRA accounts — the size of the future RMD problem determines whether this strategy matters at all.
- Find your RMD age — 73 if born 1951–1959, 75 if born 1960 or later — and count the gap years between your planned retirement and that date.
- Project your baseline gap-year income (pension, interest, dividends, any part-time clinical work) and compute your 2026-equivalent conversion capacity to the top of the 22% and 24% brackets.
- Overlay the constraint stack: mark the years either spouse is 63 or older for IRMAA exposure, and the years before 65 if you will hold marketplace coverage.
- Draft a year-by-year conversion schedule and estimate the tax bill for the first year; confirm you can pay it from taxable cash.
- Revisit the schedule every December with actual income figures before executing that year's conversion, since conversions cannot be undone.
The gap years reward the same habit that got you through residency: a written plan, executed annually, adjusted on real data. Whether you run the schedule on a spreadsheet or inside a planning tool, the protocol above works with or without us. This is education, not individualized financial advice.