A couple in their late sixties opened a January Medicare statement and watched their combined Part B premiums double. Nothing in their 2026 budget explained it. The trigger was a Roth conversion they completed in December 2024, back when a market dip made the move look cheap. Medicare calls this a two-year lookback because 2026 premiums generally use 2024 tax information. On the actual calendar, barely 13 months separated the conversion from the first higher premium.
That lag is the whole game. The income recorded on a 2026 return will generally determine 2028 Part B and Part D surcharges. The return will not be filed until 2027, but most of the useful planning ends December 31, 2026.
Who This Actually Hits
Roughly 8% of people with Medicare Part B pay the Income-Related Monthly Adjustment Amount (IRMAA). In 2026, a single filer with modified adjusted gross income at or below $109,000, or a joint filer at or below $218,000, pays the standard $202.90 Part B premium and no Part D surcharge.
A Modified Adjusted Gross Income (MAGI) for IRMAA generally means adjusted gross income (AGI) from Form 1040 plus tax-exempt interest. Municipal-bond income that escapes federal income tax still counts here.
The 2026 Brackets, in Dollars
Each tier adds a Part B surcharge to the standard premium and a Part D surcharge to the beneficiary’s drug-plan premium. The current brackets show how quickly the cost rises. The figures governing 2028 premiums have not yet been published, but the 2026 table illustrates the size of each cliff. Each amount below is per person, per month:
| Single MAGI | Joint MAGI | Part B surcharge / mo | Part D surcharge / mo |
|---|---|---|---|
| ≤ $109,000 | ≤ $218,000 | $0.00 | $0.00 |
| $109,001–$137,000 | $218,001–$274,000 | $81.20 | $14.50 |
| $137,001–$171,000 | $274,001–$342,000 | $202.90 | $37.50 |
| $171,001–$205,000 | $342,001–$410,000 | $324.60 | $60.40 |
| $205,001–$499,999 | $410,001–$749,999 | $446.30 | $83.30 |
| ≥ $500,000 | ≥ $750,000 | $487.00 | $91.00 |
A joint filer who lands one dollar above the first threshold pays approximately $2,300 in annual household surcharges. At the top tier, the combined bill approaches $13,900.
The Traps Behind the Brackets
When one spouse dies, the survivor can generally file jointly for the year of death. The following year, filing status commonly shifts to single unless another status applies. The lower single thresholds can push the same income through multiple IRMAA tiers.
Form SSA-44 is not a general cure for an expensive tax decision. It applies when household income falls following a qualifying event such as retirement, work reduction, marriage, divorce, death of a spouse, loss of pension income, or loss of income-producing property beyond the owner’s control.
A Roth conversion is not a qualifying event. Neither is a voluntary home sale. If a deliberate transaction raised MAGI, Social Security generally will not subtract it from the calculation.
What You Can Still Do Before December 31
Three moves carry most of the weight:
- Size Roth conversions with an IRMAA estimate in view. Project 2026 MAGI, use a reasonable estimate of the 2028 thresholds, and leave room for year-end dividends, capital-gain distributions, and other income. Crossing a threshold by $5,000 can cost a couple thousands in surcharges. Stopping $5,000 short may avoid the IRMAA cliff, though it can carry other long-term tax consequences.
- Use qualified charitable distributions after age 70½. Money sent directly from an IRA to an eligible charity can satisfy part or all of an RMD without entering AGI. QCD eligibility begins at 70½, even if the donor’s RMDs have not started.
- Coordinate capital gains and losses. Realized losses offset realized gains dollar for dollar. If losses exceed gains, generally only $3,000 of the remaining net loss can reduce ordinary income that year, with the balance carried forward.
The return filed in 2027 records the result. The decisions that create it happen before the ball drops.
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