The answer
Does IRMAA use last year's income?
No, IRMAA does not use last year's income; it uses your income from two years earlier.
IRMAA, the Income-Related Monthly Adjustment Amount, is a surcharge on Part B and Part D premiums for higher earners, and Social Security calculates it using your most recent tax return on file, which is generally from two years back. That means your 2026 IRMAA is based on your 2024 income. This two-year lookback is why a one-time income event, such as selling property or a large withdrawal, can raise your premium a couple of years later. If your income has since dropped because of a life-changing event, you can ask Social Security to use more current figures. To understand the timing for your situation, reach out to a licensed Goodsurance advisor at 1-888-301-8091 (TTY 711), Mon to Fri 8 am to 5 pm PT.