How Medicare IRMAA works
Everyone who enrolls in Medicare Part B pays a standard monthly premium ($202.90 in 2026). If your modified adjusted gross income (MAGI) is above a limit, you pay that premium plus an income-related adjustment, and Medicare drug coverage carries its own adjustment on top of the plan premium. The limits depend on your tax filing status, and Social Security looks at your return from two years before the premium year: the 2026 premium is set by your 2024 income.
Because the lookback is two years, a decision you make now (a Roth conversion, a large withdrawal, selling a rental property) is paid for later. And the steps are cliffs, not slopes: crossing a limit by one dollar raises the surcharge for the whole year.
2026 Part B and Part D surcharge levels
| Level | Single income (2024 MAGI) | Joint income | Part B total / month | Part D surcharge / month |
|---|---|---|---|---|
| None | $109,000 or less | $218,000 or less | $202.90 | $0.00 |
| 1 | Above $109,000 up to $137,000 | Above $218,000 up to $274,000 | $284.10 | $14.50 |
| 2 | Above $137,000 up to $171,000 | Above $274,000 up to $342,000 | $405.80 | $37.50 |
| 3 | Above $171,000 up to $205,000 | Above $342,000 up to $410,000 | $527.50 | $60.40 |
| 4 | Above $205,000 up to $500,000 (not including) | Above $410,000 up to $750,000 (not including) | $649.20 | $83.30 |
| 5 | $500,000 or more | $750,000 or more | $689.90 | $91.00 |
Source: CMS fact sheet for 2026 Medicare premiums, released 2025-11-14. Married people filing separately who lived together at any time in the year have only two surcharge levels: above $109,000 up to $391,000 (level 4), and $391,000 or more (level 5). CMS publishes new figures each fall; this page is updated once the next year's tables are available and verified.
What counts as income for a federal retiree
- Included: the taxable part of your FERS or CSRS annuity, withdrawals from a traditional TSP or IRA, the taxable part of Social Security, wages and any annual leave lump sum in your final working year, interest, dividends and capital gains, and a Roth conversion.
- Not included: qualified withdrawals from a Roth TSP or Roth IRA, the portion of your annuity that is a tax-free return of contributions, and Social Security that is not taxable.
- Also included: tax-exempt interest, which is added back to adjusted gross income.
Your first year of retirement can be unusually high because it holds a final stretch of salary and a lump-sum payout for unused annual leave, and that year's income can raise your premium two years later. Retirement is a recognized life-changing event, so you can ask Social Security to use your lower, current income.
Ways people use this calculator
- See how much additional income, such as a Roth conversion, fits under the next limit.
- Check whether a one-time withdrawal from a traditional TSP pushes a year into a higher level.
- Estimate your Medicare cost alongside FEHB in retirement when deciding whether to keep Part B.
Frequently asked questions
What is IRMAA?
IRMAA is the income-related monthly adjustment amount: an extra amount added to your Medicare Part B premium, and separately to your Part D drug-plan premium, when your modified adjusted gross income is above set limits. Most people pay the standard premium and no surcharge.
Which year's income sets my Medicare premium?
Social Security uses your tax return from two years earlier. The 2026 premium is based on your 2024 income; income you earn in 2026 sets your 2028 premium. If the return from two years back is not available, it uses the one before that.
Is IRMAA a cliff or a gradual increase?
A cliff. When your income moves from at or below a limit to even one dollar above it, the surcharge for the whole year steps up to the next level. It is not charged only on the dollars over the limit.
What counts as income for IRMAA?
Modified adjusted gross income: the adjusted gross income on your tax return plus tax-exempt interest. For a federal retiree that usually includes the taxable part of your FERS annuity, withdrawals from a traditional TSP or IRA, the taxable part of Social Security, wages in your final working year, and any Roth conversion. Qualified withdrawals from a Roth TSP or Roth IRA are not part of adjusted gross income.
Can a Roth conversion raise my Medicare premium?
Yes. A conversion is taxable income in the year you do it, and that year's income sets your premium two years later. Spreading a conversion over several years, or sizing it to stay under a limit, is one way people manage this. This page shows only the Medicare side; the Roth conversion analyzer covers the tax cost.
My income dropped because I retired. Do I still pay the higher premium?
Not necessarily. Stopping work is one of the life-changing events for which you can ask Social Security to base your premium on more recent income instead of the older return. Others include marriage, divorce, the death of a spouse, a work reduction, and the loss of income-producing property or pension income. You make the request with Social Security (Form SSA-44) and provide evidence.
Does FEHB change my IRMAA?
No. FEHB premiums do not set your IRMAA, and FEHB drug coverage is not Medicare Part D, so the Part D surcharge does not apply to it. IRMAA matters for retirees who also enroll in Medicare Part B, or in a Medicare drug plan.
Are the numbers on this page official?
They are estimates built from CMS's published tables. Social Security decides your actual IRMAA from the tax information the IRS sends it, and the base Part D premium, Medigap and Medicare Advantage premiums are not included.