A 66-year-old widower in Ohio has a $90,000 Roth conversion penciled in for December. His broker is watching the federal tax brackets. Medicare is looking over his shoulder. The conversion would join his pension, investment income, and taxable Social Security on his 2026 return. That return will generally become the income record Social Security uses to set his Medicare premiums for 2028.
He cannot know the exact cost yet. The 2028 premiums and income brackets will not be published until late 2027. What he can know is that the income is being created now. December closes the return Medicare will eventually read.
How 2026 Income Reaches Into 2028
The Income-Related Monthly Adjustment Amount (IRMAA) adds a surcharge to Medicare Part B and Part D premiums for people above certain income levels. Social Security normally looks back two years, so the return covering 2026 will generally determine what someone pays in 2028.
For this purpose, modified adjusted gross income (MAGI) is adjusted gross income from Line 11 of Form 1040 plus tax-exempt interest from Line 2a. Municipal-bond interest may escape federal income tax while still counting here. Roth conversions, traditional individual retirement account distributions, required minimum distributions (RMDs), capital gains, and the taxable portion of Social Security can also lift the number. The 2028 brackets are not known yet. The current 2026 schedule can serve as a planning reference, but not as a promise of where the future lines will land.
| 2026 MAGI (single) | Part B surcharge (per month) | Part D surcharge (per month) | Combined annual surcharge |
|---|---|---|---|
| ≤ $109,000 | $0 | $0 | $0 |
| $109,001–$137,000 | $81.20 | $14.50 | $1,148.40 |
| $137,001–$171,000 | $202.90 | $37.50 | $2,884.80 |
| $171,001–$205,000 | $324.60 | $60.40 | $4,620.00 |
| $205,001–$500,000 | $446.30 | $83.30 | $6,355.20 |
| ≥ $500,000 | $487.00 | $91.00 | $6,936.00 |
These are 2026 figures, not 2028 projections. Most joint income thresholds are double the single amounts, except the top tier, which begins at $750,000. Because the table shows per-person costs, a couple would pay about $2,297 at the first tier and $13,872 at the top.
The Cliff and the Survivor Trap
IRMAA has no gentle phase-in. Crossing a bracket by a small amount can trigger the entire next surcharge for the year. A little extra income in December can therefore cost more than the ordinary tax attached to it. Widows and widowers face a second problem. A couple may file jointly for the year one spouse dies, but the survivor commonly moves to single filing afterward. Income may fall only modestly while the Medicare brackets narrow sharply.
A pension may continue. The survivor keeps the larger of the couple’s two Social Security benefits, not both, and may still have required distributions and portfolio income. The household lost a person, but not necessarily half its income. That mismatch is how someone who never approached IRMAA as part of a couple can encounter it after becoming single.
The Appeal Form Has Boundaries
Form SSA-44 can ask Social Security to use newer, lower income after certain life changes. Those include marriage, divorce, the death of a spouse, stopping or reducing work, an involuntary loss of income-producing property, the loss of pension income, and qualifying employer settlements.
The form is valuable when income genuinely falls for one of those reasons. It does not erase income someone deliberately created. A Roth conversion, voluntary property sale, or large retirement distribution generally does not become appealable simply because it produced an expensive Medicare year. The widower may qualify for relief because of his spouse’s death if the event lowered his household income. He would not qualify merely because he later decided the $90,000 conversion was larger than Medicare liked.
Give December Decisions a Medicare Column
The precise 2028 brackets are still missing, so this is a year for ranges and cushions, not false precision. Three checks can keep a tax decision from producing a Medicare surprise:
- Project 2026 MAGI before making the final conversion or realizing another large gain. Use Line 11 plus tax-exempt interest, then compare several possible 2028 threshold estimates.
- Leave room for December dividends, interest, and mutual-fund capital-gain distributions. A conversion that fills an estimated bracket perfectly in November may overflow it when the remaining tax documents arrive.
- Look at discretionary income events together. A Roth conversion, property sale, and large retirement distribution may each fit separately. Stacking them in one calendar year can be what pushes the return into a higher tier.
December 31 does not reveal the 2028 Medicare bill. It closes the ledger that will help produce it. The price arrives later, but most of the numbers are being written now.
Contact [email protected] for any questions or corrections.
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