The $83,000 RMD Problem: Why 67-Year-Olds With Large 401(k)s Can’t Wait Until 73 to Plan

A recent Reddit thread on r/retirement spread quickly with a title that summed up a common regret: “Don’t miss the Roth Conversion window (I did).” The poster had waited until Social Security checks and required distributions stacked on top of each other, narrowing tax planning options to almost nothing. For a 67-year-old couple sitting on $1.8 million in a traditional 401(k) and planning to file Social Security at 70, that window is open right now, and it closes faster than most retirees appreciate.

The stretch between full retirement age and the first required distribution at 73 is the last time your household income is soft enough to reshape. Waste it, and the tax cascade that arrives with the first RMD becomes permanent.

The RMD That Lands on Top of Everything Else

At 73, the IRS Uniform Lifetime Table divides your prior-year 401(k) balance by 26.5. If $1.8 million grows to roughly $2.2 million by then at a moderate net return, the first-year RMD is about $83,000. It is mandatory, ordinary income, and lands on top of everything else.

Stack Social Security next. A married couple with strong earnings histories who both delay to 70 can pull down roughly $80,000 to $90,000 in combined annual benefits, boosted by the 2.8% 2026 COLA that compounds into their claim year. Add dividends and interest from the taxable account and the household clears $180,000 of modified adjusted gross income before discretionary spending.

The 2026 IRMAA thresholds for joint filers begin at $218,000, then step up at $274,000, $342,000, $410,000, and $750,000. Each tier is a hard cliff. Cross by a single dollar and the surcharge applies to the full year of Medicare premiums for both spouses.

The Two-Year Lookback Turns Age 67 Into the Decision Point

IRMAA is set using tax returns from two years earlier. Your 2028 Medicare premiums come from your 2026 return, and 2029 premiums from 2027. That is why the drawdown window closes right now for a 67-year-old, not later when the RMD hits.

The surcharges are real money. A couple in the first IRMAA tier pays roughly $2,297 per year in combined Part B and Part D surcharges above the standard premium. Tier two runs about $5,772, tier three climbs past $10,000. Combined with taxation of up to 85% of Social Security benefits, a retiree nominally in the 22% federal bracket can face an effective marginal rate close to 40% on RMD dollars. Standard Part B alone is $202.90 per month in 2026, and that is the floor before any surcharge stacks on.

Filling the 24% Bracket Without Tripping the Cliff

The 2026 24% federal bracket for joint filers runs from $211,400 to $403,550, and the standard deduction for a couple is $32,200. That leaves a retired couple with no other income room to convert north of $220,000 per year and stay inside the 24% band.

The catch is IRMAA. To dodge the first surcharge tier, MAGI on the 2026 return needs to finish under $218,000. Converting to about that line each year from 67 through 69, then living on the Roth and taxable buckets while Social Security grows at roughly 8% per year of delay, can shift $600,000 to $700,000 out of the traditional 401(k) before benefits and RMDs push income up permanently.

For the taxable side funding day-to-day spending during the conversion years, income-focused vehicles keep the drawdown gentle. Schwab U.S. Dividend Equity ETF (NYSEARCA:SCHD) yields about 3.3%, and the 10-year Treasury near 5% makes a laddered bond sleeve useful for the first time in a decade. Persistent services inflation running at roughly 4% year over year also argues for keeping some equity exposure through the conversion window.

Three Moves to Make This Quarter

1. Project your age-73 RMD by taking your expected 401(k) balance at that point and dividing by 26.5, then layer in projected Social Security. If the combined figure clears the $218,000 IRMAA cliff for joint filers, you have a conversion job to finish before 70.
2. Size each annual Roth conversion so your 2026 MAGI lands around $217,000. That fills the 24% bracket, stays off the first IRMAA tier, and locks in current rates ahead of the next scheduled bracket sunset.
3. If crossing the first IRMAA threshold looks unavoidable in a given year, front-load the conversion into a single tier rather than dribbling into two. A fee-only advisor paid a flat retainer earns the fee back on tier management alone once joint MAGI exceeds $218,000.

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