What IRMAA is, and why it surprises people twice
IRMAA, the income-related monthly adjustment amount, is Medicare's income test: above certain income levels, you pay more for Part B and Part D. It surprises people in two specific ways. First, the two year lookback: your 2026 premiums are set by the income on your 2024 tax return, so the year you sold the house, converted an IRA, or took a final bonus before retiring echoes into your premiums two years later, often after the income itself is long gone. Second, every threshold is a cliff, not a phase-in: crossing a line by one dollar triggers the entire tier's surcharge for the whole year, for both spouses if you both have Medicare.
This calculator places your MAGI in the 2026 table and then does the two things a table cannot: it prices the cliff behind you (what the dollars over the last line are actually costing) and the cliff ahead (how much headroom you have before the next one, and what crossing it would add). Those two numbers are what make IRMAA plannable instead of just annoying.
The 2026 IRMAA table
Final figures from CMS (published November 14, 2025), based on 2024 MAGI. Part B amounts are the total monthly premium; Part D amounts are added to whatever your drug plan itself charges.
| Single MAGI | Joint MAGI | Part B / month | Part D surcharge |
|---|---|---|---|
| $109,000 or less | $218,000 or less | $202.90 | none |
| to $137,000 | to $274,000 | $284.10 | $14.50 |
| to $171,000 | to $342,000 | $405.80 | $37.50 |
| to $205,000 | to $410,000 | $527.50 | $60.40 |
| under $500,000 | under $750,000 | $649.20 | $83.30 |
| $500,000 and up | $750,000 and up | $689.90 | $91.00 |
Married filing separately has its own harsher schedule: the standard premium up to $109,000, then straight to the $649.20 tier, and the top tier from $391,000. MAGI here means adjusted gross income plus tax-exempt interest, which is why municipal bond income, invisible to the income tax, still counts against these lines.
Worked example
A couple filing jointly, both on Medicare with drug plans, had a $280,000 MAGI in 2024 (a Roth conversion year). That lands in the second surcharge tier: Part B becomes $405.80 each and Part D adds $37.50 each: $443.30 a month per person, $886.60 as a couple, $10,639.20 a year, of which $5,769.60 is IRMAA.
The sharper number: they are just $6,000 over the $274,000 line, and those six thousand dollars are costing $3,472.80 a year in extra premiums: an effective 57.9% rate on the income past the line, on top of the income tax it already paid. Had the conversion been $6,000 smaller, the surcharge tier would have been one lower. The next cliff sits at $342,000, with $3,470.40 a year at stake.
Planning around the cliffs, honestly
The two year lookback makes IRMAA a planning problem, and the cliffs make precision pay. The classic collisions: a Roth conversion sized without checking the lines (our Roth conversion calculator now has a reason to know your IRMAA thresholds), a large capital gain taken in one year instead of straddling two, and RMDs stacking on top of everything else after 73. The classic reliefs: qualified charitable distributions come straight out of MAGI, gains can sometimes be split across tax years, and conversions can be sized to fill a tier without breaching the next line. None of this is advice to earn less; it is advice to notice that $1 of income at the wrong line can cost hundreds of premium dollars, which is a rate worth planning around.
And if the high-income year is already behind you and your income has since dropped for one of Social Security's listed life-changing events (stopping or reducing work, marriage, divorce, a spouse's death, losing a pension, a disaster loss), do not just absorb the surcharge: file form SSA-44 with evidence of the newer income, and SSA can re-run the numbers on the current reality instead of the two year old return. Premiums are re-determined every year, so even without an appeal, one expensive year buys exactly one expensive premium year.