A $1.8 Million 401(k) RMD Could Cost You $974 a Year in Hidden Medicare Surcharges. Here’s How to Stop It

Consider a widowed 73-year-old with $1.8 million still sitting in her 401(k). Her first required minimum distribution lands this year, and because her husband passed two years ago, she now files as a single taxpayer. That change in filing status is where the trouble starts, and it is the exact scenario dominating recent r/retirement threads.

The RMD itself is straightforward. Using the IRS Uniform Lifetime Table divisor of 26.5 at age 73, she owes a withdrawal of roughly $67,900. What she often does not model is what that withdrawal does to her Medicare premiums two years from now.

The Two-Year IRMAA Lookback Nobody Priced In

Medicare’s Income-Related Monthly Adjustment Amount uses a two-year lookback on modified adjusted gross income. Her 2026 tax return determines her 2028 Part B premium, and the surcharge brackets for a single filer are unforgiving:

1. MAGI at or below $109,000 pays the standard $202.90 monthly Part B premium in 2026. No surcharge.
2. MAGI between $109,000 and $137,000 adds an $81.20 monthly surcharge, taking the total to $284.10. That is an extra $974 a year.
3. Cross $137,000 and the surcharge jumps to $202.90 a month, or a total premium of $405.80, an extra $2,435 a year.
4. The top bracket at or above $500,000 in MAGI carries a $487.00 monthly surcharge and a $689.90 total premium.

Where Her MAGI Actually Lands

Stack the pieces. The $67,900 RMD counts as ordinary income. Social Security of $36,000 adds $30,600 taxable at the 85% threshold. Bond and CD interest rounds out the picture, plausible given today’s 10-year Treasury is yielding around 4.7% and FDIC national average 12-month CD sits near 1.7%.

She has stepped over the first single-filer threshold by less than $5,000, and it will cost her nearly a thousand dollars in 2028 Part B premiums she did not owe the year before. If the 2026 Social Security COLA of 2.8% repeats and her balance grows through the year, next year’s RMD will be larger and the IRMAA cliff gets closer, not farther.

Also worth naming: the same MAGI that triggers IRMAA has already pushed 85% of her Social Security into the taxable column and dropped her into the 22% federal bracket, which for single filers in 2026 begins at $50,400 and runs to $105,700. Effective marginal rates in this zone routinely land near 40% once IRMAA is included.

Three Moves That Change the 2028 Bill

1. Run the RMD math against the single-filer IRMAA table before December 31. If your projected MAGI is within $10,000 of a bracket, a Qualified Charitable Distribution paid directly from the IRA to a 501(c)(3) reduces the taxable portion of the RMD dollar for dollar and is excluded from MAGI entirely.
2. Model Roth conversions during any pre-RMD gap year, especially if you retire between 65 and 73. Filling the 22% bracket voluntarily now costs less than filling it involuntarily later while paying a Part B surcharge on top.
3. If your MAGI already exceeds the first IRMAA threshold at $109,000 single or $218,000 joint, the tax-planning fee alone justifies a fee-only advisor. The break-even math is easy: a single bracket jump can cost more than $2,400 a year in premiums for the rest of your life.

The RMD is a fixed obligation. The premium surcharge attached to it is a variable you can plan around.

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