A $1.5 Million 401(k) at 62 Becomes Two Very Different Retirements at 73, Depending on One Decision
A couple retiring at 62 with $1.5 million in a traditional 401(k) faces a silent eleven-year countdown, and the clock does not care whether they notice it.
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Picture a couple, both 62, staring at a combined 401(k) balance of $1.5 million. They plan to stop working within the year, delay Social Security, and let the account ride. Eleven years later, at age 73, the IRS forces a decision they never actually made: the first required minimum distribution. Whether that moment feels like income or an ambush depends almost entirely on what they do between now and then.
The pivot point is the Roth conversion window from age 62 to 73. Use it, and RMDs stay small and the tax cascade never triggers. Ignore it, and a balance that compounds at market rates lands in the highest tax terrain of the retiree’s life.
Why 73 Is a Tax Cliff for Retirees
Under SECURE 2.0, RMDs begin at 73. The first-year divisor from the IRS Uniform Lifetime Table is 26.5. A $1.5 million traditional balance compounding at roughly 7% for eleven years lands near $3 million, which produces an inaugural RMD of roughly $113,000 (illustrative). The real problem is what that number pulls in behind it.
At that income level, up to 85% of Social Security benefits become taxable, and the couple crosses the 2026 IRMAA threshold of $218,000 for joint filers once combined income, capital gains, and interest are layered on top. The first IRMAA tier alone adds $81.20 per person per month to Part B, on top of the standard $202.90 premium, plus a $14.50 Part D surcharge. Two people, two years of surcharges (Medicare uses a two-year lookback), and the RMD has quietly cost several thousand dollars in premiums before a dime of income tax is paid.
A Fork in the Road at 62
Retirement A: the couple lets the traditional balance ride. They live on cash and taxable brokerage income from 62 to 70, claim Social Security at 70, and take the first RMD at 73. Their taxable income that year sits near the top of the 22% federal bracket, part of it gets taxed at 24%, 85% of Social Security is pulled into taxable income, and IRMAA lands on both spouses. Effective marginal rates on the last dollars of the RMD approach 40% once premium surcharges and Social Security taxation are included.
Retirement B: the couple converts roughly $90,000 to $100,000 per year from the traditional 401(k) to a Roth IRA during the low-income years between 62 and 70, staying inside the 22% bracket that runs to $206,700 for joint filers and beneath the IRMAA line. With the 2026 standard deduction of $32,200 for married couples filing jointly, a $100,000 conversion nets an effective federal tax cost near 12% to 14% (we sized up this exact quiet-years opportunity in a free guide to the Roth conversion window). By 73, the traditional balance is closer to $1.5 to $1.7 million rather than $3 million, the first RMD is closer to $60,000, and Social Security taxation and IRMAA never trigger.
What the Rate Environment Adds
The math is friendlier now than it was three years ago. The 10-year Treasury yield at 5% means the taxable side of the portfolio can carry the couple’s living expenses from 62 to 70 without forcing large 401(k) draws that would defeat the conversion strategy. The 2027 Social Security COLA tracking near 3% makes delayed claiming at 70 more valuable, which in turn makes the pre-70 conversion window even more useful because taxable income is genuinely low.
Three Actions Before the Window Closes
- Model the first RMD now. Take today’s balance, compound at 6% to 7% to age 73, and divide by 26.5. If the answer sits above $80,000, the RMD alone will push a couple with Social Security across the $218,000 IRMAA line.
- Run partial Roth conversions that fill the 22% bracket, not the 24%. The jump from 22% to 24% at $206,700 for joint filers is small; the jump from clear of IRMAA to inside the first tier is not. Keep MAGI under $218,000.
- Coordinate conversions with Social Security timing. Convert aggressively from 62 to 69, then throttle back the year before claiming at 70. Once benefits start, every converted dollar risks pulling Social Security into taxable income at the 85% rate.
The couple who does nothing between 62 and 73 has effectively chosen Retirement A. The window to choose otherwise is exactly eleven years wide, and it closes on a birthday.
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Jake has been been working in financial media for almost 15 years. He focuses on all things personal finance for 24/7 Wall St. with high hopes to educate and entertain. Most recently, Jake spent 12 years working various roles at The Motley Fool. He started copy editing fool.com content, worked on premium and marketing campaigns, and helped launch The Ascent, a personal finance brand.
His work has been featured on platforms like MSN, Yahoo Finance, USA Today, and more. He's written about credit cards, social security, ETFs, savings accounts, and just about anything else you can imagine when thinking about money. Jake love to cook, play golf, and tell people he's never had a cavity. (It's true!)
