What is IRMAA, and why does my Medicare premium depend on income?
IRMAA is an extra monthly charge on Medicare Part B and Part D when your income is above certain lines.
The short version
Everyone on Medicare pays a standard Part B premium ($202.90 a month in 2026). If your income from two years earlier was above a threshold, you pay that premium plus a surcharge. The surcharge is called the income-related monthly adjustment amount, or IRMAA.
It is a cliff, not a ramp
Unlike tax brackets, IRMAA tiers are cliffs. For a single filer in 2026, income of $109,000 has no surcharge. Income of $109,001 adds $81.20 a month to Part B (plus $14.50 for Part D). One dollar over the line changes the whole tier.
Which income counts
Medicare uses modified adjusted gross income (MAGI) from your tax return two years back: your 2024 return sets 2026 premiums. In practice, a Roth conversion, a large capital gain, or a big IRA withdrawal today can raise premiums two years from now.
What you can do
- Spread large income events across several years so you stay under a line.
- If your income fell because you retired, ask Social Security to use a newer year (form SSA-44).
Check your tier with the IRMAA calculator →
Sources: Medicare.gov; SSA.