IRMAA is a Medicare premium surcharge on Part B and Part D for beneficiaries whose income two years earlier crossed a threshold, and it can add hundreds of dollars a month per person.
Why this matters two to eight years from retirement
IRMAA runs on a two-year lookback, so the income you report in the first years of retirement, including any Roth conversion you execute, sets your Medicare premium two years later. A large conversion or a big capital gain in one year can trigger a surcharge you feel two years after the decision, once the cause is easy to forget. Managing MAGI in the years before and during Medicare enrollment is the only way to keep this predictable instead of a surprise that lands with the premium bill.
What this looks like for one household
In 2026, a beneficiary in the top IRMAA tier pays $689.90 a month for Part B alone, versus the standard $202.90, plus a Part D surcharge of up to $91.00 a month, according to the Centers for Medicare & Medicaid Services. Medicare sets those 2026 premiums from 2024 income. The dollar figures change most years; check the current page for the year you are planning around. The mechanism stays the same: a couple converting $150,000 in a single tax year, on top of Social Security and portfolio income, can cross a bracket they never would have hit spreading the same conversion across three smaller years instead. Sizing a conversion against the IRMAA threshold, not only the tax bracket, keeps it from becoming a Medicare bill two years later.
What to do if a one-time event inflates your income
A large capital gain, a business sale, or a big conversion in one year can trigger IRMAA even for a household whose income usually sits well below the threshold. The Social Security Administration accepts appeals for specific life-changing events, retirement or a work stoppage that lowered income among them, though a one-time gain from a planned conversion does not usually qualify on its own. The better fix is sizing the conversion against the threshold before you file, not appealing after the bill arrives.
Related reading
If the decisions on this page are ahead of you, the two of you can work through them with Robert Boeck before any of them becomes permanent.
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