An envelope shows up from Social Security and your Medicare premium has gone up, sometimes by a lot. It has a name most people never hear until it hits them: IRMAA, the income-related monthly adjustment amount. It's a surcharge stacked on your standard Part B and Part D premiums once your income crosses certain lines. Below: what triggers it, why it runs on income from two years ago, why it behaves like a cliff, and what you can do about it.
What is IRMAA, the Medicare high income surcharge?
The Medicare high income surcharge has an official name, and IRMAA is the short version of it. Most people on Medicare pay the standard Part B premium, $202.90 a month in 2026. IRMAA is an extra amount on top of that, and on top of your Part D premium, once your income crosses a threshold. The government normally covers about 75% of your Part B cost. Cross a line and you pay a larger share instead: 35%, 50%, 65%, 80% or 85% of the total, depending on your tier. The higher your income, the bigger the surcharge. Source: SSA, Medicare Premiums: Rules for Higher-Income Beneficiaries (2026 figures).
The two-year lookback
IRMAA ignores this year's income. It runs on your tax return from two years ago. Your 2026 surcharge is generally set by the return you filed in 2025 for tax year 2024, and if SSA couldn't get that one it used 2023 instead. So one spike back then, selling a house, a big Roth conversion, a year with extra capital gains, can drive a surcharge today even though your income has since dropped back to normal.
What counts as income for IRMAA (MAGI)?
IRMAA uses your MAGI, and the official definition reaches wider than the income you pay tax on. In SSA's words it's your adjusted gross income plus your tax-exempt interest income. That matters:
- Tax-exempt (muni-bond) interest still counts. You can owe zero income tax on it and still have it push you over an IRMAA line.
- Capital gains from selling a home or stock flow in.
- Traditional IRA and 401(k) withdrawals count.
- Roth conversions count in the year you convert.
So the income that triggers IRMAA is wider than your taxable income. Knowing what lands in that bucket is how you stay under a line, and that is what Medicare surcharge planning amounts to: watching one number in the years before it counts. Note the IRMAA Social Security connection too, because SSA is the agency that decides your amount and usually deducts it straight from your check.
Why it's a cliff, not a slope
IRMAA doesn't phase in. It's a cliff. One dollar over a threshold moves you into the whole next tier at the full higher surcharge, for the entire year, on both Part B and Part D. That's why the lines are worth planning around. A tiny overage costs real money that a little timing would have avoided.
Here is where the lines sit for 2026. The income column is the MAGI on the return you filed in 2025 for tax year 2024:
| 2024 MAGI — single | 2024 MAGI — joint | Part B total / month | Part D add-on / month |
|---|---|---|---|
| $109,000 or less | $218,000 or less | $202.90 | plan premium only |
| over $109,000 to $137,000 | over $218,000 to $274,000 | $284.10 | +$14.50 |
| over $137,000 to $171,000 | over $274,000 to $342,000 | $405.80 | +$37.50 |
| over $171,000 to $205,000 | over $342,000 to $410,000 | $527.50 | +$60.40 |
| over $205,000, under $500,000 | over $410,000, under $750,000 | $649.20 | +$83.30 |
| $500,000 and above | $750,000 and above | $689.90 | +$91.00 |
Crossing that first line by a single dollar costs $81.20 a month, about $974 for the year for one person, and roughly twice that for a couple both on Medicare, before the Part D add-on. Married filing separately, having lived with your spouse at any time during the year, runs on its own shorter schedule. Source: CMS, 2026 Medicare Parts A & B premiums and deductibles; SSA, 2026 IRMAA guidance.
If your income already fell: Form SSA-44
A life-changing event that cut your income, retirement or work stoppage, loss of a pension, the death of a spouse, divorce, means you don't have to accept a surcharge built on your old, higher income. File Form SSA-44 and ask Social Security to use your current income instead. One thing to get right before you start: that isn't an appeal, and SSA says most people in this position shouldn't file one. We walk through the form, the eight qualifying events and the evidence in how to file a Medicare IRMAA appeal. Going forward you can also manage MAGI on purpose: spread big withdrawals across years and size Roth conversions to stay under a bracket line.
Go to the source
The brackets move every year, so check the current figures at the source rather than trusting a number you found somewhere. Handle all of it at medicare.gov and ssa.gov, never with a middleman who found you first. If a pitch makes you panic or reach for your wallet, it's bait.
Free 1-page "IRMAA Cliff" cheat sheet
The 2026 brackets, what counts toward MAGI, the two-year lookback and the SSA-44 route, on a single page.
Get the cheat sheet→Sources
• Medicare.gov — Medicare costs 2026 (standard Part B $202.90, deductible $283)
• SSA — Medicare Premiums: Rules for Higher-Income Beneficiaries (2026 IRMAA brackets + MAGI)
• SSA — Form SSA-44 (Medicare IRMAA — Life-Changing Event)
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Common questions
What income does IRMAA use?
IRMAA uses your MAGI, meaning your adjusted gross income plus any tax-exempt interest income. Tax-exempt muni-bond interest still counts. Capital gains, traditional IRA withdrawals, and Roth conversions all flow into it, so the income that triggers IRMAA is broader than the income you pay tax on.
Why is my 2026 Medicare premium based on old income?
IRMAA runs on a two-year lookback. Your 2026 surcharge is generally set by the tax return filed in 2025 for tax year 2024. A one-time 2024 income spike, such as a home sale or a big Roth conversion, can raise your 2026 premium even if your income has since dropped.
How do I appeal or lower IRMAA?
If your income fell because of a life-changing event (retirement, work stoppage, loss of a pension, death of a spouse, or divorce), file Form SSA-44 to have Social Security use your current, lower income instead of the two-year-old return. You can also manage future MAGI by spreading out withdrawals and keeping Roth conversions under a bracket line.