IRMAA Brackets and the Two-Year Lookback
Medicare's "premium" is not really a premium — for higher-income retirees, it is a means-tested surcharge that ratchets up by income bracket. The Income-Related Monthly Adjustment Amount (IRMAA) can add $443/month to your Part B and another $85/month to your Part D, per person, for couples whose income two years ago crossed certain thresholds.
The 2025 brackets (based on 2023 MAGI)
| Single MAGI | MFJ MAGI | Part B premium | Part D surcharge |
|---|---|---|---|
| ≤ $106,000 | ≤ $212,000 | $185.00 | $0.00 |
| $106,001–$133,000 | $212,001–$266,000 | $259.00 | $13.70 |
| $133,001–$167,000 | $266,001–$334,000 | $370.00 | $35.30 |
| $167,001–$200,000 | $334,001–$400,000 | $480.90 | $57.00 |
| $200,001–$500,000 | $400,001–$750,000 | $591.90 | $78.60 |
| > $500,000 | > $750,000 | $628.90 | $85.80 |
The amounts apply per beneficiary. A married couple both on Medicare pay double the bracket amount.
The two-year lookback
IRMAA for any year is based on your modified AGI from two years prior. 2025 premiums use 2023 tax return data, transmitted from the IRS to SSA. The lookback creates two specific planning problems:
- The conversion-year shock. A large Roth conversion in 2023 raises 2025 Medicare premiums. Most people doing conversions are aware of the current-year income tax; many do not realize the same income spikes Medicare two years later.
- The one-time event. Selling a business or vacation home in 2023, taking a large IRA distribution in 2023, or recognizing a large RSU vest can push 2025 into the top bracket — an extra $5,300+ per person of Medicare cost in a single year, on income that was a one-off.
The cliff effect
IRMAA is a cliff, not a phase-in. One dollar of MAGI above a bracket boundary moves you into the next bracket for the entire year. For a single beneficiary crossing from $106,000 to $106,001 MAGI, the cost increase is about $74/month in Part B plus $13.70 in Part D — roughly $1,053 of additional annual Medicare cost on $1 of additional income. That is a >100,000% effective marginal rate at the boundary.
Planning around the cliff: in years near a boundary, defer or accelerate income to land cleanly below the threshold, or push fully into the next bracket so the cliff is amortized over more income.
The life-changing event appeal
Form SSA-44 lets you request an IRMAA reduction if your income has dropped due to a "life-changing event" — including:
- Marriage, divorce, or death of a spouse
- Work stoppage or reduction (most relevant: retirement)
- Loss of income-producing property
- Loss of pension income
- Employer settlement payment due to bankruptcy or closure
If you retired in 2024, you can file SSA-44 to ask SSA to use 2024 or projected 2025 income instead of 2023 for the 2025 IRMAA determination. The appeal is usually granted when documentation supports the income reduction.
What MAGI includes
For IRMAA purposes, MAGI = AGI + tax-exempt interest (municipal bond income). It does not include the Roth conversion amount above AGI — the conversion is already in AGI as ordinary income. The tax-exempt-interest add-back catches retirees who shifted into munis specifically to manage Medicare premiums.
Common mistakes
- Forgetting tax-exempt interest counts. The municipal-bond hedge that avoids federal income tax still drives IRMAA.
- Doing a "tax-bracket-fill" Roth conversion without IRMAA awareness. A conversion that stays neatly inside the 22% bracket can still cross an IRMAA cliff, doubling the effective cost.
- Missing the SSA-44 deadline. The appeal must generally be filed within 60 days of the initial IRMAA determination notice, though SSA often accepts late filings with cause.
- Treating IRMAA as deductible. The surcharge portion is not separately deductible for income-tax purposes beyond the standard medical-expense itemized deduction (which most retirees do not exceed).
Sources
- Social Security Act §1839(i), IRMAA for Part B (Cornell LII): law.cornell.edu/uscode/text/42/1395r
- Social Security Act §1860D-13(a)(7), IRMAA for Part D: law.cornell.edu/uscode/text/42/1395w-113
- CMS, "2025 Medicare Parts A & B Premiums and Deductibles" (Nov 8, 2024): cms.gov 2025 Part B premium fact sheet
- SSA Form SSA-44, Medicare IRMAA Life-Changing Event: ssa.gov/forms/ssa-44.pdf
- SSA, "Medicare Premiums: Rules for Higher-Income Beneficiaries" (Publication 05-10536): ssa.gov/pubs/EN-05-10536.pdf
RetirementCheck101 maps your projected MAGI against IRMAA brackets so a conversion doesn't catch you by surprise. Explore the free educational tool.