A $900,000 401(k) at 73 Produces a $34,000 RMD That Quietly Lifts a Couple’s Medicare Premiums, and Here’s the Fix

A 73-year-old retiree in Cleveland posted on a personal-finance forum that her first required minimum distribution arrived smoothly. Her tax software flagged something else. Both her and her husband’s Medicare Part B premiums were about to rise, and the trigger was a $34,000 line item she did not control.

Their situation is a common one. A $900,000 traditional 401(k), both spouses on Medicare, combined Social Security and a small pension that sits comfortably below the first IRMAA threshold. The RMD did not look like much on its own. It was the combination that broke the seal.

How $900,000 Becomes a $34,000 Bill

The IRS Uniform Lifetime Table assigns a divisor of 26.5 at age 73. Divide $900,000 by 26.5 and the first-year RMD lands at roughly $33,962. Most readers round to $34,000 and move on.

That single number does three things at once. It enters federal taxable income as ordinary income. It counts toward the Social Security taxation formula, pushing up to 85% of combined benefits into the taxable column. And it lands in modified adjusted gross income, which Medicare uses, with a two-year lookback, to set next year’s Part B and Part D premiums.

The 2026 standard Part B premium is about $203 per month. For a married couple filing jointly with MAGI at or below $218,000, that is the bill. Cross $218,000 by even a dollar and the premium jumps to about $284 per month per spouse. Cross $274,000 and it hits about $406. Part D adds a smaller surcharge on top, about $15 per person at the first tier and about $38 at the second.

The Math the RMD Does Quietly

Picture the couple with $52,000 in combined Social Security, a $48,000 pension, and $85,000 in dividends and interest from a taxable brokerage. They sit at $185,000 MAGI, well under the first cliff. Add the $34,000 RMD and the line moves to roughly $219,000. They are one thousand dollars over the threshold.

That single dollar triggers the full first-tier surcharge for both spouses. Two people times roughly $81 per month for Part B works out to about $1,949 a year. Add two times $14.50 for Part D and the household surcharge climbs to roughly $2,297. None of it phases in. It applies in full at the first dollar of overage.

If the same couple has higher dividend income or a larger RMD because the balance sits closer to $1.3 million, they can land in the $274,000 to $342,000 tier instead. The Part B portion alone runs near $4,870 per year for the household, and Part D adds another $900.

Layer in federal tax on the RMD itself (the 22% joint bracket runs from $100,800 to $211,400 in 2026) and the effective cost of that last $34,000 withdrawal climbs toward 27% before state tax.

The Fix That Actually Works at 73

The cleanest tool for this couple is the Qualified Charitable Distribution. After rolling the 401(k) to a traditional IRA, each spouse can direct up to $108,000 of their RMD straight to a qualified public charity in 2026. The amount counts toward the RMD, but it never lands in MAGI. A $10,000 QCD from the $34,000 obligation pulls income back under the $218,000 line and erases the IRMAA surcharge for both spouses.

Three steps make this concrete:

1. Run a draft 1040 in November using estimated dividends and the actual RMD. If MAGI lands within $10,000 of $218,000 or $274,000, the IRMAA math is in play and worth a phone call to the IRA custodian before December.
2. Direct the QCD from the IRA custodian to the charity before December 31. The check must travel from the IRA directly to the qualified charity. A reimbursement of a personal donation does not qualify, and a 401(k) cannot make a QCD, which is why the rollover step matters.
3. If a one-time event (loss of pension, a spouse’s death, work stoppage) caused the income spike two years ago, file Form SSA-44. Social Security can reset the IRMAA tier for the current year without waiting for the lookback to catch up.

The threshold crossing is what drives the cost. A household with a $900,000 balance can almost always engineer income back under the line if they look at the full stack of pensions, dividends and Social Security before December rather than after the surcharge notice arrives in the mail.