How much should I convert to Roth this year?

By Mario Bailey · Published June 9, 2026 · Last reviewed July 1, 2026

For a single filer who retired at 62 with $900,000 in a traditional IRA and expects $50,040 per year from Social Security at 67, the answer at age 64 is roughly $105,700 converted to fill the 22% bracket. At age 67 the same dollar target fills the same bracket on paper but leaves the filer meaningfully deeper into the 22% band because Social Security now stacks on top. At age 75, the account has been so thoroughly converted that RMDs are under $2,000 and additional conversions make no sense at all. "How much this year" is the wrong unit. The right unit is the full window from retirement to RMD start, and the answer changes every year within that window.

Why the window closes on two schedules, not one

Conversions are most valuable when bracket space sits empty. Two events fill that space back up on independent schedules. Social Security claims phase in over the 62-to-70 claiming range. Required Minimum Distributions begin at the Required Beginning Date (RBD), which for those born 1960 or later is April 1 of the year following the year they turn 75, per SECURE 2.0. Pub. 590-B Appendix B Table III governs the Uniform Lifetime divisors. At age 75 the divisor is 24.6, forcing roughly 4.1% of the account out whether the owner wants it or not.

Because Social Security and RMDs operate on different clocks, the optimal conversion amount for a specific filer changes year by year through the window. Planning only the current year's conversion without modeling the full trajectory risks under-converting in the early years (when SS is not yet running and the bracket is wide open), over-converting later (when SS and RMDs together crowd the bracket), or triggering the IRMAA lookback cliff by accident. The two-year IRMAA lookback means 2026 MAGI determines 2028 Medicare premiums; a conversion that looks fine in isolation can generate surcharges two years out.

2026 single-filer bracket structure

Under Rev. Proc. 2025-32, the 2026 single-filer brackets on taxable income are as follows. Taxable income is gross income minus the standard deduction ($16,100 for single filers, plus $2,050 for filers age 65 or older).

Taxable income (single, 2026)	Marginal rate	Note
$0 – $12,400	10%
$12,401 – $50,400	12%
$50,401 – $105,700	22%	Top of 22% target
$105,701 – $201,775	24%
Source: Rev. Proc. 2025-32. Brackets are taxable income, after standard deduction.

The calculator's fill-bracket logic computes available headroom as: (bracket ceiling in taxable income) minus (pre-conversion taxable income). For a single filer age 64 with only $4,000 of interest: the standard deduction ($16,100) exceeds the $4,000 income, so pre-conversion taxable income is $0. Headroom = $105,700 - $0 = $105,700. The conversion is set to $105,700. After converting, gross income = $4,000 + $105,700 = $109,700, and taxable income = $109,700 - $16,100 = $93,600. The conversion amount equals the bracket ceiling, but the resulting taxable income is below it because the standard deduction applies to the full gross income.

Worked example: age 64, $900k traditional IRA, Texas

Single filer, born 1962, retired at 62. Current year is the 2026 tax year; the filer is 64. Account balances: $900,000 traditional IRA, $200,000 Roth IRA. Only other income is $4,000 of taxable interest. Social Security claimed at FRA 67, projected at $4,170 per month ($50,040 per year). No state income tax (Texas). Life expectancy modeled to 92. Six percent nominal return, 2.5% inflation. Running the four canonical scenarios through the calculator:

Strategy	Lifetime tax + IRMAA	vs. do-nothing
Do nothing	$441,502	baseline
Fill to top of 12%	$344,691	-$96,811
Fill to top of 22%	$342,167	-$99,335
Fill to top of 24%	$338,563	-$102,939
Single, born 1962, $900k trad IRA, $200k Roth, $4k interest, SS $4,170/mo at FRA 67, TX (no state tax), 6% return, 2.5% inflation, life expectancy 92.

The fill-24 strategy wins here because this filer's projected RMDs, compounding on $900,000 at 6% for eleven years before the RBD, would eventually push ordinary income above the 24% threshold anyway. Converting at 24% now, and shrinking the future taxable balance, beats deferring the tax into a bracket that cannot be avoided later.

What the conversion amount actually looks like year by year

The fill-22 scenario (second-best for this filer) illustrates how the conversion amount evolves even when the strategic target (top of 22%) never changes. The year-by-year output from the calculator:

Age	Conversion	Taxable SS	Taxable income	RMD
64	$105,700	$0	$93,600	$0
65	$105,700	$0	$91,096	$0
66	$105,700	$0	$90,631	$0
67	$105,700	$42,534	$132,688	$0
68	$105,700	$42,534	$132,200	$0
69	$105,700	$42,534	$131,699	$0
70	$105,700	$42,534	$131,186	$0
71	$105,700	$42,534	$130,659	$0
72	$105,700	$42,534	$130,120	$0
73	$105,700	$42,534	$129,567	$0
74	$105,700	$42,534	$129,000	$0
75	$0	$2,640	$0	$1,261
Fill-to-22% scenario. Taxable income differs from gross conversion because of the standard deduction plus age-65 additional amount. Taxable income declines each year from age 67 onward because inflation-indexed brackets expand the 22% ceiling faster than the fixed SS benefit grows. At age 75 the Roth balance is so large that traditional IRA RMDs become trivial. Row 67 highlighted because Social Security starts, pushing taxable income above the 22% ceiling despite the identical conversion amount.

Notice what happens at age 67. The conversion amount is unchanged at $105,700 but taxable income jumps to $132,688 because $42,534 of Social Security benefits become taxable under the Pub. 915 provisional income formula. The filer is now in the 24% bracket on the top slice of the conversion, even while nominally pursuing a "fill-22%" strategy. A filer who wants to stay strictly within 22% at age 67 and beyond needs to reduce the conversion amount by the amount of SS income that crowded the bracket, not keep converting the same dollar amount as in the pre-SS years. This recalculation must happen each year because the provisional income denominator changes as the traditional IRA balance shrinks and the inflation adjustment to the brackets shifts.

The fill-22 strategy produces a taxable income of $0 at age 75 in this example because aggressive converting through the window has shrunk the traditional IRA to the point where RMDs are under $2,000 and the remaining balance sits in Roth. The strategy has effectively pre-paid the tax and eliminated the RMD problem entirely for this filer.

The five inputs that change every year

Each year's conversion decision depends on: current bracket headroom (bracket ceiling minus pre-conversion taxable income), whether the conversion crosses an IRMAA tier two years out, any RMD required this year, the projected RMD in the near future if the account is still large, and the SS inclusion rate at the planned conversion amount. None of those five is static. Each one shifts as the account balance compounds, bracket thresholds inch upward with inflation, SS starts or continues, and the RBD draws closer. No single year's answer survives contact with the following year's updated inputs without revision.

When the answer is zero

A still-working filer earning $400,000 who asks "how much should I convert this year" will find the answer is zero, or very close to it. Bracket filling assumes unused bracket space. A high-income earner in the 32% or 35% bracket on wages alone has no space at 22% or 24%. Any conversion lands at 32%-plus, which is nearly always higher than the projected RMD rate after retirement income drops. Converting at 32% to avoid 24% later is the wrong direction. The strategy only creates value when the current-year marginal rate on the conversion is lower than the projected future marginal rate on the forced distribution. If wages consume all the favorable brackets, conversion should wait until the year wages stop. For many late-career professionals, that means the answer to "how much should I convert this year" genuinely is zero for several more years, and that is the right answer.