Medicare IRMAA Calculator

The two-year lookback that catches retirees off guard

The surcharge this tool estimates is not based on what you earn the year you pay it. Medicare looks back two years. Your 2026 Part B and Part D premiums are set by the modified adjusted gross income on your 2024 tax return, the most recent return the IRS has shared with the Social Security Administration when 2026 rates are calculated. That lag is why a clean retirement year can still arrive with a surcharge attached. If you sold a rental, took a large IRA distribution, or exercised options in 2024, the bill shows up in 2026, often a surprise to people who assume their now lower income should govern.

MAGI here means your adjusted gross income plus any tax exempt municipal bond interest. Roth withdrawals do not count, which is one reason Roth balances are so useful in retirement. The tool uses the 2026 thresholds shown in its bracket table, which are estimated from the 2025 figures and standard inflation indexing. Treat them as planning estimates, not final numbers, until Medicare publishes the official 2026 amounts in the fall of 2025.

How the surcharge stacks on Part B and Part D

IRMAA is not a tax on your income. It is a flat dollar add on to two premiums. Each bracket carries a fixed Part B surcharge and a separate Part D surcharge, and you pay both every month for the full year. The Part D piece applies even though your prescription coverage comes from a private plan, because the surcharge is collected by Medicare on top of whatever your plan charges. Married couples each pay their own surcharge once both are enrolled, so a couple in a high bracket pays the figure twice.

A single filer at $160,000 of MAGI

Take a single retiree whose 2024 MAGI lands at $160,000. That figure sits above the second threshold but at or below $171,000, so the calculator places them in the third bracket: a Part B add on of $200 a month and a Part D add on of $37 a month. Combined, that is $237 every month, which the tool annualizes to $2,844 for the year. Here is the arithmetic the page runs.

The chart shows how that single filer's annual surcharge jumps from one tier to the next. Notice the steps are tall and flat, not a smooth ramp.

Cliffs, not slopes

The most expensive mistake in IRMAA planning is treating these thresholds like ordinary tax brackets. They are not marginal. One dollar of MAGI over a line moves your entire premium to the higher tier. A retiree who lands at $171,001 pays the same Part B and Part D add on as someone at $204,000. That is why I tell clients to manage the last few thousand dollars of income near a threshold with real care. A Roth conversion that pushes you $500 past a cliff can cost more in surcharges than the conversion saves. Watch capital gains distributions from mutual funds in December too, since they can quietly nudge you over without any action on your part.

A practical tip: if you are doing Roth conversions in your sixties to draw down a traditional IRA, size each conversion to stop just under the next threshold rather than filling a tax bracket. The IRMAA cliff is often the binding constraint, not the income tax rate.

Appealing a surcharge after a life change

If your income dropped because of a qualifying life changing event, you do not have to accept a surcharge built on stale income. File Form SSA-44 with the Social Security Administration. Qualifying events include retirement, marriage, divorce, the death of a spouse, and loss of pension income. The form lets Social Security use your estimated current year income instead of the two year old figure. Retirement is the most common reason this matters, a high earning final working year sets a surcharge that no longer reflects your situation.

Does selling my house trigger IRMAA?

It can, but only the taxable gain counts toward MAGI. If you are single you can exclude up to $250,000 of gain on a primary residence you have lived in for two of the last five years, and married couples can exclude up to $500,000. Gain above the exclusion lands in your AGI two years later and may push you into a higher bracket. A large home sale is one of the classic one time events that creates a temporary surcharge, and it is generally not appealable through Form SSA-44 because a property sale is not a listed life changing event.

Is the standard Part B premium included in these figures?

No. This calculator shows only the IRMAA surcharge, the extra amount above the standard premium that everyone pays. Your total Part B cost is the standard premium plus the Part B surcharge shown here. The Part D surcharge is likewise added on top of whatever your prescription drug plan charges. Budget for the base premiums separately when you plan your full Medicare cost.