IRMAA (the Income-Related Monthly Adjustment Amount) raises your Medicare Part B premium based on your MAGI from two years ago. The tiers are cliffs, not phase-ins: one extra dollar of income — a Roth conversion, a capital gain, an RMD — can cost the full year's surcharge. Check how close you are.
| MAGI up to | Monthly surcharge | Annual cost |
|---|---|---|
| $109K← you | — | $0 |
| $137K | $81.20 | $974 |
| $171K | $202.90 | $2.4K |
| $205K | $324.60 | $3.9K |
| $500K | $446.30 | $5.4K |
| Above all thresholds | $487.00 | $5.8K |
Part B surcharges shown (2026, SSA POMS HI 01101.020). Part D carries additional smaller surcharges at the same thresholds. IRMAA is assessed on MAGI from two years prior — plan conversions with the lag in mind.
The free planner runs this calculation inside your full picture — taxes, Social Security, RMDs, and withdrawals together — and returns a ranked list of moves worth real dollars, each with the math shown.
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