Why is my Medicare premium higher because of IRMAA?

Why is your Medicare bill so much higher than your neighbor’s for the exact same coverage? Because Medicare charges high earners a surcharge called IRMAA, the Income-Related Monthly Adjustment Amount. It sits on top of the standard premium for Part B and Part D, and it’s driven entirely by your income, not your health.

What you actually pay

For 2026, the standard Medicare Part B premium is $202.90 a month. That’s what most people pay. Once your income crosses the first IRMAA threshold, a surcharge stacks on top, and it climbs through six tiers.

At the high end, the numbers stop being trivial. The top Part B tier in 2026 runs $689.90 a month, the $202.90 base plus a $487.00 surcharge, and there’s a separate Part D surcharge of up to $91.00 a month layered onto whatever your drug plan already costs. For a couple where both spouses are on Medicare, every one of these is per person, so you double it.

The two-year lookback is the trap

Here’s what catches people. Your 2026 IRMAA is based on your income from 2024. Medicare looks back two years, because that’s the most recent tax return it has on file when premiums are set.

That delay is the second-order effect almost nobody plans for. A big one-time income event, a business sale, a large Roth conversion, a giant capital gain, doesn’t just raise your taxes that year. It raises your Medicare premiums two years later, often after you’ve forgotten the event even happened. People do a smart conversion at 63 and get blindsided by a Medicare bill at 65 they never connected to it.

IRMAA is a cliff, not a ramp

The cruelest part of the design: IRMAA jumps in steps, not slopes. Earn one dollar over a threshold and you owe the entire next tier’s surcharge, not a sliver of it. A single dollar of extra income can cost a couple thousands of dollars across the year in higher premiums.

That makes the dollars right at each breakpoint extraordinarily expensive, and it’s why managing income near a threshold is worth real attention. A capital gain you could have deferred, an IRA withdrawal you could have trimmed, a conversion sized a hair too large, any of them can tip you over.

How affluent retirees manage it

The defense starts years early. Doing Roth conversions in your 60s, before RMDs and Social Security stack onto your income, shrinks the forced income that later drives IRMAA. A Qualified Charitable Distribution sends RMD money straight to charity and keeps it out of the income that’s measured. And if your income dropped because of a “life-changing event” like retirement or the death of a spouse, you can file Form SSA-44 to ask Medicare to use current income instead of the two-year-old figure.

IRMAA punishes the unplanned income spike and rewards the household that smooths its income on purpose. See the full IRMAA brackets and plan your income against them before you trip a tier you can’t undo.