Combined Part B and Part D IRMAA surcharges can hit $578 a month, which adds up to $6,936 annually, deducted directly from your Social Security check.
Your 2026 Part D surcharge uses 2024 income, so a large Roth conversion or property sale can trigger extra costs two years later.
Tax-exempt municipal bond interest still counts toward MAGI, quietly pushing retirees past the $109,000 threshold that triggers Part D surcharges.
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When most people learn about Medicare IRMAA surcharges, they often hear about Part B first. The income-related premium hikes that happen with doctor and outpatient coverages are often the first to get discussed in retirement circles. Not to mention, these are the same conditions that can push a monthly premium from $202.90 all the way up to $689.90.
What doesn't get mentioned as often is Part D, or the prescription drug coverage side of Medicare, which has its own separate IRMAA surcharge. The thing to remember here is that this surcharge also comes out of your Social Security check the exact same way Part B does.
As a result, most people take their time and research what kind of charges they will get with Part B and plan for this number. However, when their Social Security deposit comes the next month, it feels off, as in being lower than they had expected. The reason? They weren't planning for the Part D surcharge, which had been running in the background the whole time.
The Part D surcharge is what applies after you see that your modified adjusted gross income, better known as MAGI, crosses certain thresholds. In 2026, any individual with a MAGI of $109,000 or less, or a married couple filing jointly with a MAGI of $218,000 or less, will not have to pay a Part D surcharge.
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However, if your MAGI goes above those income levels, the story changes completely. In 2026, the monthly amount starts at $14.50 for income above $109,000 and up to $137,000, and it rises to $37.50 for any income above $137,000 up to $171,000. The story gets more expensive when you are charged $60.40 for income above $171,000 all the way up to $205,000.
When you go above $205,000 in MAGI, the next tier is even harder to swallow, as it hits $83.30 monthly if your income goes all the way up to $500,000. After the income level crosses the $500,000 mark, you can reach the maximum surcharge of $91 per month. For married couples filing jointly, the income limit is a bit higher for the $91 surcharge, as the top MAGI tier starts at $750,000.
The important part is that the $91 is not your total Part D premium; it is the IRMAA surcharge that is added to your plan's premium. So if your prescription drug plan charges $40 a month, someone in the highest IRMAA tier would pay $131 a month for Part D.
This is where the numbers start to matter. The same income that triggers Part B IRMAA can also trigger a Part D IRMAA. Social Security says that if you have both Part B and prescription drug coverage and your income is above the applicable threshold, you pay the income-related adjustments for both.
At the highest income level in 2026, Part B carries a $487 monthly IRMAA on top of the standard $202.90 premium. Part D adds another $91 a month. Together, that is $578 a month in IRMAA alone. Over 12 months, this comes to $6,936.
This still does not include the standard Part B premium or the premium charged by your Part D plan. If you are a retiree who has spent years trying to build up a predictable income plan, it's easy to miss this surcharge. Even if you think you know exactly to the dollar what your Social Security benefit is supposed to be, the deposit that is received may be smaller because Medicare premiums are taken out of Social Security checks before being deposited into any bank accounts.
