Medicare IRMAA Surcharge Calculator

How the IRMAA surcharge works

Most people pay the standard Medicare Part B premium and whatever their Part D drug plan charges. Above certain income levels Medicare adds an extra monthly amount on top of both — the Income-Related Monthly Adjustment Amount, or IRMAA. It is not a tax on the income itself; it is a permanent-feeling increase in what your health coverage costs for a year.

The income it looks at is two years old

Your 2026 premiums are set from the modified adjusted gross income on your 2024 tax return, because that is the most recent return the IRS has finished processing when premiums are announced each fall. MAGI here means your adjusted gross income plus any tax-exempt interest, so it captures wages, pensions, IRA and 401(k) withdrawals, Roth conversions, capital gains, the taxable portion of Social Security, and municipal bond interest. Withdrawals from a Roth account you already own do not count.

That two-year lag is the whole planning problem. A large distribution, a property sale, or a conversion done in the year you retire arrives as higher Medicare premiums two years later — frequently in the first year your income has actually dropped.

The brackets are cliffs, not slopes

Cross a threshold by a single dollar and you owe the entire surcharge for that tier, the same as someone thousands of dollars above it. There is no phase-in and no proration. Near a boundary at the end of the year, a modest change — deferring a withdrawal, harvesting a loss, making a charitable distribution straight from an IRA — can be worth more than it looks. Each spouse enrolled in Medicare pays the surcharge separately from the same joint income, so for a couple the household cost is double the figures above.

If your income has already fallen

Retiring is itself grounds for an appeal. Social Security will replace the two-year-old figure with your current estimate when a life-changing event caused the drop — work stoppage or reduction, marriage, divorce, death of a spouse, or loss of a pension among them. The form is SSA-44, filed with documentation such as a letter from your employer. It is one of the few places in the Medicare system where asking reliably works, and it is missed constantly.

Planning the other direction, the Roth conversion calculator finds the largest conversion that stays under your next IRMAA tier, and the RMD projection shows how much required income is coming your way in future years.

Frequently asked questions

What income counts toward IRMAA?

Modified adjusted gross income: your adjusted gross income plus any tax-exempt interest. That sweeps in wages, pensions, IRA and 401(k) withdrawals, Roth conversions, capital gains, the taxable part of Social Security, and municipal bond interest. Withdrawals from a Roth account you already own are not included.

Why is Medicare looking at a tax return from two years ago?

Because it is the most recent return the IRS has finished processing when premiums are set each fall. The two-year lag is the reason retirement-year planning matters: a large Roth conversion or a home sale shows up in your Medicare premiums two years later, long after the money is spent.

What happens if I go one dollar over a bracket?

You pay the entire surcharge for that tier. IRMAA is a cliff, not a phase-in — crossing a threshold by a single dollar costs the same as crossing it by thousands. This is why the brackets are worth checking before you take an extra distribution late in the year.

Can I get IRMAA reduced after I retire?

Yes, if a life-changing event caused the drop in income. Work stoppage or reduction, marriage, divorce, death of a spouse, loss of a pension, and a few others qualify. File form SSA-44 with documentation and Social Security will use your current estimated income instead of the two-year-old return.

Do both spouses pay the surcharge?

Each person enrolled in Medicare pays it separately, based on the same joint income. For a couple where both are enrolled, the household cost is twice the per-person figure — which is what the "both spouses" option above shows.

Does a Roth conversion trigger IRMAA?

It can. A conversion is ordinary income and counts fully in the MAGI that sets your premiums two years later. Converting up to — but not across — the next tier is the usual way to handle it, and the Roth conversion calculator on this site works out exactly where that line falls.