Why Paying $60,000 in Taxes at 63 Is the Smartest Move a Couple With $1.5 Million Can Make

A couple, both 63, sitting on $1.5 million in traditional 401(k) assets, writing a voluntary check to the IRS for $60,000. On paper it looks like tax malpractice. In practice, it may be the highest-return decision they will make between now and Medicare enrollment.

The scenario shows up constantly on retirement forums and in advisor Q&As. As one caller framed the question on a recent podcast episode, the debate really comes down to “taxes today versus taxes in the future”. For this couple, the future is worse than they think.

Bracket Window That Closes at 73

For a married couple filing jointly in 2026, the 22% bracket runs from $100,800 to $211,400 of taxable income, with a $32,200 standard deduction stacked on top. The 24% bracket does not end until $403,550. That gives this couple a wide runway to convert traditional dollars into Roth dollars at a known, historically low rate.

Do nothing, and the math gets ugly fast. At a 6% return, a $1.5 million balance roughly doubles by age 73, when RMDs begin. The first-year RMD alone can approach six figures, layered on top of two Social Security checks that will already be inflating with each 3.3%-ish COLA. That combination pushes ordinary income deep into the 24% bracket and makes up to 85% of Social Security taxable. The effective marginal rate on the next dollar climbs toward 40% once IRMAA is added.

Paying $60,000 in federal tax now to move roughly a quarter-million dollars into a Roth is, in effect, buying out that future liability at a discount. The Roth then grows tax-free, carries no RMD for the original owners, and passes to heirs under a 10-year tax-free window.

IRMAA Cost Nobody Prices Correctly

Here is the part that trips up 63-year-olds. Medicare uses a two-year MAGI lookback. A conversion executed in 2026 shows up on the 2028 Part B and Part D premium calculation, right as this couple enrolls at 65.

The 2026 IRMAA tiers for joint filers are unforgiving:

1. MAGI at or below $218,000: standard Part B premium of $202.90 per month, no Part D surcharge.
2. MAGI above $218,000 up to $274,000: Part B jumps to $284.10 and Part D adds $14.50.
3. MAGI above $274,000 up to $342,000: Part B hits $405.80 and Part D adds $37.50, per person.
4. MAGI above $342,000 up to $410,000: Part B climbs to $527.50.

A conversion sized to generate $60,000 in federal tax will likely land the couple in the second tier for one year. That is roughly $80 per month per person in Part B surcharges, plus small Part D adjustments. Call it about $2,000 in one-time premium noise, in exchange for permanently removing a quarter-million dollars from a future RMD stream that would trigger IRMAA every year for the rest of their lives.

Why Rates Reinforce the Case

The 10-year Treasury sits at 4.95%, near a 52-week high, and the fed funds upper bound is 3.75%. Cash and short bonds are producing real yield again, which means the taxable account used to pay the $60,000 conversion tax is not sacrificing much growth. Paying conversion tax from outside the IRA is what makes the strategy work; pulling tax dollars from the converted amount cuts the benefit in half.

Three Moves Before Year-End

1. Model a conversion that fills the 22% bracket to the $211,400 ceiling, then price the IRMAA surcharge that 2026 MAGI will trigger in 2028. If the tier-two surcharge is the ceiling, the trade almost always pencils out.
2. Pay the tax from a taxable brokerage account so the full converted balance stays invested. Every dollar of tax withheld from the IRA is a dollar that never compounds tax-free.
3. Repeat the exercise annually through age 72. The window between retirement and RMDs is the only time most couples control their marginal rate, and we sized up exactly how to use those quiet years in a free Roth conversion guide. After age 73, the IRS controls it.

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