How IRMAA works

Most Medicare beneficiaries pay the standard Part B premium. But if your income for Medicare purposes — MAGI — is above a threshold, you pay extra: IRMAA. It applies to both Part B and Part D, uses five income tiers, and is a true cliff — crossing a boundary by one dollar means the full surcharge for that tier applies to every dollar of your income, not just the amount above the line.

2026 IRMAA brackets (CMS-confirmed)

Married filing separately gets hit hardest

If you lived with your spouse at any point during the year but file separately, there's no graduated middle tier. Cross $109,000 and you jump straight to the second-highest bracket ($649.20/month) — and at $391,000 or more, you're at the top tier. This compressed structure is one of the costliest filing-status traps in the tax code for couples near Medicare age.

Planning around the two-year lookback

Because IRMAA looks back two years, the income decisions you make today don't hit your premium until two years later — which is both a trap and an opportunity. A large Roth conversion, an unusually big capital gain, or your first RMD year can all push you over a threshold without warning. If a life-changing event (retirement, divorce, death of a spouse) caused your income to drop since the lookback year, you can file Form SSA-44 to ask Social Security to use more current income instead.

For broader retirement income planning, see how withdrawals affect your overall tax position with the income tax calculator and net income calculator, and model long-term savings with the retirement calculator.