The RMD Tax Trap That Costs Retirees Six Figures Without These Three Moves Before Year-End
Most retirees never realize a single 401(k) distribution can quietly trigger a Medicare surcharge bill two years later, and by the time that notice arrives, it is already too late to undo the damage.
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A 73-year-old sitting on $1.6 million inside a traditional 401(k) is about to cross a threshold most retirees never see coming. The first required minimum distribution arrives on schedule, and a second, invisible bill starts building inside Medicare two years later.
The RMD math is straightforward. Using the IRS Uniform Lifetime Table, the divisor at age 73 is 26.5, which turns a $1.6 million balance into a first-year distribution of roughly $60,400. That amount is not optional. It counts as ordinary income the day it leaves the plan, and it resets higher every year the account keeps growing.
Where the Tax Bomb Actually Detonates
The $60,400 is only the visible cost. Stack it on top of a typical Social Security benefit and any pension or dividend income, and modified adjusted gross income for a single filer easily clears the first IRMAA threshold of $109,000, or $218,000 for a couple filing jointly. IRMAA functions as a cliff: exceeding a threshold by even one dollar triggers the full surcharge for that entire tier, not just the amount over the line.
Once MAGI crosses that first threshold, 2026 Medicare Part B premiums step up from the standard $202.90 per month to $284.10, and Part D layers another $14.50 per month on top of the plan premium. For a single retiree in that first surcharge bracket, the combined annual cost is close to $1,150. Push MAGI past $137,000 and Part B jumps again to $405.80 per month, which adds up to roughly $2,435 per year in Part B surcharges alone. It is worth noting that 2026 IRMAA surcharge amounts rose about 9% from 2025 levels, even as the income thresholds themselves moved up only around 3%.
The trap is the two-year lookback. A 2026 RMD sets the IRMAA bracket that appears on 2028 Medicare premiums. By the time that surcharge notice arrives, the income that triggered it is two years old and cannot be unwound.
Why the First RMD Hits Harder Than the Next One
For someone whose RMD age was pushed to 73 under SECURE 2.0, the first distribution can legally be deferred until April 1 of the following year. That option sounds generous until you run the numbers: it stacks two full RMDs into a single tax year, doubling the income spike and often bumping the retiree into a higher IRMAA tier and a higher federal bracket at the same time. Taking the first RMD in the year you turn 73 is almost always the cheaper path.
Inflation is quietly compounding this problem. The 2026 Social Security COLA came in at 2.5%, meaning larger monthly benefit checks. Those checks are welcome, but they also lift MAGI closer to the IRMAA cliffs with each passing year.
What Actually Softens the Blow
Qualified Charitable Distributions are the cleanest offset available to a 73-year-old. A QCD sent directly from an IRA satisfies the RMD dollar for dollar and never shows up in AGI. The 2026 annual QCD ceiling is $111,000 per person, up from $108,000 in 2025. For a retiree who already gives to charity, routing $10,000 or $20,000 of the $60,400 through a QCD can be the difference between clearing the $109,000 threshold and staying comfortably beneath it. QCDs are also more valuable in 2026 than in prior years because the One Big Beautiful Bill Act placed new limits on itemized charitable deductions for some taxpayers, while QCDs remain entirely unaffected by those restrictions. One important caveat: QCDs are not permitted from a 401(k), so a direct rollover to an IRA before year-end is the prerequisite.
Where the after-tax proceeds land also matters. The FDIC national average for a 12-month CD sits near 1.7%, while the 10-year Treasury is paying around 4.65%. On a fully reinvested $60,400 RMD, that spread is worth roughly $1,800 more in annual interest, and Treasury interest escapes state income tax.
Three Moves Before December 31
- Run the RMD yourself. Take your December 31, 2025 balance, divide by 26.5, and treat that as a floor. If the account has grown in 2026, next year’s RMD will be higher again on a smaller divisor.
- Model the IRMAA cliff before withdrawing. Add the RMD to expected Social Security (up to 85% taxable), pension, and investment income. If the total lands within $5,000 of $109,000 single or $218,000 joint, a QCD or a modest Roth conversion completed earlier in the year is worth the effort to stay under.
- Roll a slice to an IRA now. QCDs, more flexible beneficiary options, and easier Roth conversions all live on the IRA side. Complete the plan’s RMD first, then move the rest.
Editor’s note: This update corrects the 2026 Social Security COLA from 2.8% to the actual announced figure of 2.5%, refreshes the 10-year Treasury yield to approximately 4.65% based on current market data, confirms the 2026 QCD limit at $111,000 per person (up from $108,000 in 2025), and adds context on how the One Big Beautiful Bill Act of 2026 has made QCDs a more attractive giving vehicle by restricting some itemized charitable deductions.
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Marc Guberti is a personal finance writer who has written for US News & World Report, Business Insider, Newsweek and other publications. He also hosts the Breakthrough Success Podcast which teaches listeners how to use content marketing to grow their businesses.
