Most people assume everyone pays the same Medicare premium. They do not. The Income-Related Monthly Adjustment Amount, IRMAA, is a surcharge that can add hundreds of dollars a month to your Part B and Part D premiums if your income is high, and it is one of the most overlooked costs in retirement.
How IRMAA works
The Social Security Administration looks at your Modified Adjusted Gross Income (MAGI) from two years ago to set this year's premium. So your 2025 premiums are based on your 2023 tax return. Cross a threshold by even one dollar and you jump an entire surcharge tier.
Why it catches people off guard
- A large Roth conversion, capital gain, or RMD can push you over a bracket
- The surcharge applies to both Part B and Part D, per person
- It is a "cliff," not a phase-in, one dollar over means the full higher tier
- A life change (retirement, loss of income) can be appealed with form SSA-44
How to minimize it
Plan income two years ahead. Spread Roth conversions across years to stay under a threshold, harvest gains deliberately, use tax-free buckets (Roth and cash-value life insurance) for large one-off expenses, and consider Qualified Charitable Distributions to reduce MAGI. If your income dropped because of a qualifying life event, file an appeal, many people overpay simply because they never did.
IRMAA thresholds and amounts are set annually by CMS; confirm current figures at Medicare.gov or SSA.gov. This is educational information, not tax advice.