Roth Conversions in Retirement: The 60–75 Window

There's a window — typically between the day you retire and the day RMDs begin — when your taxable income is lower than it has been in decades and lower than it will ever be again. Converting traditional IRA money to Roth during this window is one of the highest-leverage moves in retirement tax planning. This guide explains the math, identifies the traps, and walks through a concrete example.

Why a window exists at all

During your working years, income is high. During RMDs, the IRS forces distributions whether you need the money or not. But the years in between — after you leave your job and before mandatory distributions start at age 73 or 75 — often look like this:

• No W-2 income, no self-employment income
• Social Security not yet claimed (if you're delaying to 70)
• RMDs haven't started
• Portfolio withdrawals are the only income

This is the window. Your AGI may be the lowest it has been since your 20s. The difference between converting nothing and converting strategically during this window can easily exceed $150,000 in lifetime federal taxes for a couple with a $1.5M traditional IRA balance — not counting the estate tax benefit of passing a tax-free Roth to heirs.

Who benefits most from conversions in this window

Roth conversions in the 60–75 window make the most sense when:

• You have a large traditional IRA or 401(k) — $500K+ that will generate substantial RMDs starting at 73 or 75.
• You're delaying Social Security — every year you delay SS to 70 is a year with lower base income, creating more conversion room.
• Your heirs are in a higher bracket than you — they'd pay ordinary income tax on inherited IRA distributions under the 10-year rule; a Roth conversion now eliminates that tax.
• You expect higher rates or income in the future — RMDs can stack on top of SS to push a couple into 22–24% territory permanently.
• You're under IRMAA thresholds today — conversions that keep you below Medicare surcharge cliffs preserve thousands in annual healthcare costs.

Conversions are less compelling when your traditional IRA is small (RMDs won't be burdensome), your heirs are in low brackets, or you'll need the converted funds within five years (the 5-year rule applies to earnings).

The 2026 bracket math: where the opportunity is

For 2026, the tax brackets for married filing jointly (MFJ) are:¹

*Approximate AGI adds back the 2026 standard deduction of $32,200 (MFJ). MAGI for IRMAA purposes is typically close to AGI for most retirees.

For single filers in 2026:¹

*Adds back the 2026 standard deduction of $16,100 (single).

The IRMAA cliff: the trap that catches most DIY converters

If your MAGI (roughly AGI + tax-exempt interest) exceeds $218,000 (MFJ) or $109,000 (single) in 2026, you'll pay a Medicare IRMAA surcharge on both Part B and Part D premiums for the following year.² The surcharges are not small:

For a couple who just barely crosses the $218K IRMAA Tier 1 line with a Roth conversion, the surcharge is roughly $2,300 extra in Medicare premiums per year, per couple — an immediate, two-person cost. And IRMAA is a cliff, not a ramp: $1 over the threshold triggers the full surcharge.

This is why "fill the 22% bracket" advice — which sounds reasonable on paper — often backfires. The 22% bracket for MFJ tops out around $243,600 AGI. That's $25,600 above the $218K IRMAA threshold. A couple who converts to the top of 22% will owe IRMAA surcharges the following year. The right target is often the 22% bracket up to the IRMAA cliff, not all the way to the top of 22%.

A concrete year-by-year example

Consider a married couple who both retire at 62 in 2026. They have $1.8M in traditional IRA/401(k), $150K in a joint taxable brokerage, and $80K in Roth IRAs. Combined Social Security at 70 is projected at $64,000/year. They need $95,000/year in spending.

Ages 62–69: the prime conversion window

Base income is nearly zero — no SS, no RMDs. They pull $95K from the traditional IRA for spending. Their AGI is approximately $95,000. With the 2026 standard deduction of $32,200 (MFJ), taxable income is about $62,800 — solidly in the 12% bracket.

They have room to convert an additional ~$38,000/year before hitting the top of the 12% bracket ($100,800 taxable), bringing total AGI to about $133,000 — still below the $218K IRMAA threshold.

Over 8 years (ages 62–69), converting $38,000/year at an average 12% federal rate moves $304,000 from taxable-at-death to tax-free. All future earnings on that $304K — potentially decades of compounding — come out tax-free.

Age 70: Social Security begins

At 70, combined SS of $64,000/year begins. Up to 85% of SS benefits are taxable, adding approximately $54,400 to AGI. Combined with ~$30,000 in portfolio withdrawals, AGI is now about $84,400. They still have conversion room to reach $133K AGI (~$48,600/year), but the window is shrinking.

Age 73: RMDs begin

By age 73, if the couple has converted $350,000 over the prior 11 years, the traditional IRA balance might be around $2.0M (after withdrawals and growth). The first-year RMD on $2.0M at age 73 is approximately $75,200 (using IRS Uniform Lifetime Table divisor of 26.5).³

RMDs of $75,200 plus $54,400 taxable SS = $129,600 AGI. There's now limited room for conversions without crossing the IRMAA threshold at $218K ($88,400 of headroom). The window hasn't completely closed — but it's much tighter.

The counterfactual: no conversions

If the couple converts nothing and the portfolio grows to $2.4M by age 73, the first RMD is approximately $90,600. AGI from RMDs + SS alone is ~$145,000. By age 80, on a $2.2M balance, RMDs approach $110,000/year — pushing the couple into the 22% bracket even before accounting for conversions or other income. The couple has lost the window entirely.

The QCD alternative after 70½

Once you reach age 70½, you can direct up to $111,000 per year (2026 limit, indexed) directly from your IRA to a qualified charity as a Qualified Charitable Distribution.⁴ A QCD satisfies your RMD, counts as a distribution, and is excluded from gross income entirely — it never appears in AGI. For charitably inclined retirees, QCDs and Roth conversions are complementary tools, not alternatives: use QCDs to reduce the RMD you'd otherwise pay tax on, and convert the remaining balance systematically.

Common mistakes

Converting in December using estimated income

IRMAA is determined by MAGI for the year, and Roth conversions are irrevocable. Converting in December based on a rough income estimate risks crossing an IRMAA tier. Convert earlier in the year when you have better visibility into total annual income.

Forgetting state income tax

Roth conversions are federal ordinary income and taxable in most states. A couple in a 5–6% state income tax bracket adds that marginal rate on top of the federal 12% or 22%, making the effective rate 17–28%. This doesn't necessarily make conversions wrong — it makes them more expensive and requires the federal math to be more compelling to justify.

Converting too much in one year chasing a "large window"

Converting $300,000 in a single year to "get it done" may seem efficient but typically results in most of the conversion being taxed at 22–24% when a more gradual fill-the-bracket approach over 8–10 years would have achieved the same result at 12%. Time, not size, is the advantage of the window.

Ignoring the five-year rule

Roth IRA earnings on converted amounts must stay in the account 5 years (or until age 59½, whichever is later) to be distributed tax-free. If you convert at age 60 and draw from that specific conversion's earnings at age 62, the earnings are taxable. Contributions and converted principal (not earnings) are always accessible without tax or penalty after the conversion 5-year clock on that conversion.

When to hire a retirement income specialist

Roth conversion strategy involves modeling multiple accounts, tax brackets, IRMAA thresholds, state taxes, RMD projections, SS taxation, and estate goals simultaneously — often 20+ years forward. A mistake that crosses an IRMAA threshold by $5,000 can cost $2,300+ annually in Medicare surcharges, potentially for many years. Professionals who specialize in retirement income planning (not generalist advisors) run scenario analyses across this full set of variables before recommending a conversion amount for a specific year.

If you have over $500,000 in traditional IRA/401(k) accounts and at least a few years before RMDs begin, a professional conversion analysis typically pays for itself many times over.