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Most people on Medicare pay the standard Part B premium. About one in twelve pays more, sometimes a lot more, because of a surcharge called IRMAA. It stands for Income-Related Monthly Adjustment Amount, and it catches people off guard because it is based on income from two years ago, including one-time spikes like selling a house or cashing out retirement accounts.
How it works
Social Security looks at the modified adjusted gross income (MAGI) on your tax return from two years prior. MAGI is your adjusted gross income plus tax-exempt interest, so municipal bond interest counts even though it is not taxed. If that number is above the threshold for your filing status, a surcharge is added to your Part B premium and, separately, to your Part D premium.
For 2026, the numbers come from your 2024 tax return. Single filers with MAGI of $109,000 or less pay the standard $202.90 Part B premium and no Part D surcharge. Above that, there are five more tiers. The Part B premium climbs to $284.10, $405.80, $527.50, $649.20, and finally $689.90 a month at the top tier, which starts at $500,000 for single filers. Married couples filing jointly get roughly double the thresholds, starting at $218,000 and topping out at $750,000. The Part D surcharge runs from $14.50 to $91 a month on top of your plan’s premium.
The figures come from the Centers for Medicare and Medicaid Services, released each fall. They move a little every year with inflation, so the exact thresholds shift, but the structure stays the same.
The two-year lookback is the trap
Because IRMAA uses income from two years earlier, a single unusual year follows you. Sell a business, take a big IRA distribution, do a large Roth conversion, realize capital gains on a property sale, and your Medicare premiums jump two years later even if your income is back to normal. About 8 percent of Part B beneficiaries pay IRMAA in a given year, and a meaningful share of them are paying because of one spike, not ongoing high income.
If you are planning a large Roth conversion or asset sale in your 60s, run the IRMAA math before you execute. Crossing a threshold by a few thousand dollars can cost thousands in surcharges over the following year. Sometimes splitting a conversion across two tax years keeps you under the line.
You can appeal, and many people should
If your income has dropped since the tax year Medicare used, you can ask Social Security to recalculate. The appeal uses Form SSA-44 and requires a qualifying life-changing event: retirement or reduced work hours, marriage, divorce, death of a spouse, or loss of income-producing property. You provide evidence of the event and your current income, and Social Security adjusts the surcharge.
This is not a loophole. It is the designed process. The most common successful appeal is retirement: your 2024 return shows your last full working year, your actual income is now much lower, and the surcharge gets reduced or removed. If you retired recently and got an IRMAA notice, file the appeal before you pay a year of surcharges you do not owe.
What does not help
Appeals based on disagreement with the thresholds themselves go nowhere. The brackets are set by law and adjusted annually. And switching to a Medicare Advantage plan does not avoid IRMAA; the surcharge applies to Part B and Part D regardless of whether your coverage comes from Original Medicare or a private plan.
The realistic strategies are timing large income events, using the appeal when life changes your income, and keeping an eye on MAGI in the years before Medicare starts. If you are still mapping out the basics of what Medicare charges, the parts A through D guide is the place to start.
