Does IRMAA Affect Your Medicare Part D Premium? Yes, and It Is Billed Separately

Does IRMAA affect your Medicare Part D premium? The separate surcharge

IRMAA applies to two premiums: Part B medical insurance and Part D prescription drug coverage. The Social Security Administration uses the same income determination for both, based on your modified adjusted gross income from two years earlier. For 2026 premiums, that means your 2024 tax return.

The Part D surcharge is added to whatever your drug plan charges. If your plan premium is $40 a month and your Part D IRMAA is $14.50, you pay $54.50 for drug coverage. If your plan premium is $0, you still pay the $14.50. The surcharge follows your income, not your plan choice, so shopping for a cheaper plan does not remove it.

Here is the 2026 Part D IRMAA schedule for a single filer, per the SSA figures as published:

Married couples filing jointly use doubled thresholds, and each spouse pays their own surcharge. Two spouses in the first tier owe $29 a month combined, $348 a year, on top of two plan premiums. At the top tier, a couple owes $182 a month, $2,184 a year, for the Part D surcharge alone.

Who collects it, and why the bill looks odd

The Part D surcharge usually goes to Medicare, not to your drug plan. Most people see it deducted from their Social Security benefit alongside the Part B surcharge, or billed directly if they do not receive Social Security. Your plan still bills you its own premium separately.

That split billing is the source of most of the confusion I hear about. People call the plan, the plan says it charges only its premium, and both sides are right. The plan never sees your IRMAA money. If your Part D surcharge looks wrong, the call goes to Social Security, not to the plan.

One more wrinkle: if you are in a Medicare Advantage plan that includes drug coverage, you still owe the Part D IRMAA. The Advantage plan premium and the Part D surcharge are separate charges, and the surcharge applies even when the plan advertises a $0 premium. Our Medicare Advantage guide covers that overlap.

The $0 premium trap

This is the case that catches people. You pick a Part D plan with a $0 premium because your prescriptions are cheap and you like the price. Then the IRMAA notice arrives, and you owe $14.50 or $37.80 a month for drug coverage you thought was free.

Nothing went wrong. The $0 was the plan premium. The surcharge is a Medicare charge layered on top, and it applies to every Part D enrollee whose income crosses the threshold. The only way to avoid it is to stay under the threshold, or to not carry Part D at all, and dropping Part D to dodge a surcharge usually costs more in late-enrollment penalties later.

Medigap is the one piece IRMAA does not touch. A Medicare Supplement premium carries no IRMAA surcharge. That distinction matters for planning: a higher-income retiree pays more for Part B and Part D, but the same Medigap premium as everyone else their age in their state.

What actually moves the number

The surcharge follows your MAGI from two years ago, so the levers are the same ones that move Part B IRMAA: Roth conversions, capital gains, a home sale, a big retirement account withdrawal. Each can push you a tier higher for a full calendar year. Our Roth conversion guide works through the conversion-year spike.

If a life-changing event cut your income, a new determination is available through Form SSA-44. Retirement, marriage, divorce, death of a spouse, and loss of income-producing property all qualify. Our SSA-44 guide covers the filing.

Run your income through our IRMAA calculator and look at both columns, not just Part B. The Part D surcharge is smaller, but it is the one people forget to budget, and a forgotten $91 a month is still $1,092 a year.

The question I keep coming back to

Why does the system bill these separately at all? Part B and Part D come from different laws passed years apart, and the billing never merged. That is a history answer, not a logic answer, and it does not help you pay the bill.

What helps is treating IRMAA as one number. Add your Part B surcharge and your Part D surcharge together when you plan retirement income, and judge every Roth conversion or asset sale against the combined total. The Part D piece alone rarely changes a decision. The combined total sometimes does.

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