The short answer
Most people know about the IRMAA surcharge on Part B, but there's a separate one on Part D that high earners often forget. If your income is above the IRMAA thresholds, you pay an extra amount on top of your Part D drug plan premium — and it applies whether you have a stand-alone Part D plan or a Medicare Advantage plan that includes drug coverage.
So a high-income beneficiary faces two surcharges, not one, and the Part D piece catches people off guard.
How it's calculated and billed
The Part D IRMAA uses the same income thresholds and two-year lookback as the Part B surcharge — it's based on your modified adjusted gross income from two years prior. The amount is set by your income tier. Our guide to the 2026 IRMAA brackets shows those tiers.
Here's a billing quirk: even though the surcharge relates to your drug plan, it's typically paid to Medicare (often deducted from Social Security), not to your Part D insurer. So you pay your plan its premium and Medicare the surcharge separately.
What to know
The Part D surcharge applies even if you have a very cheap or $0-premium drug plan, because it's based on your income, not your plan's premium. And it applies to the drug coverage inside a Medicare Advantage plan too. If your income drops due to a life change, the same appeal process that applies to Part B IRMAA applies here.
The takeaway: if you're a higher earner, budget for both surcharges. Our doctor and drug coverage tool helps you plan your Part D coverage.
Frequently Asked Questions
What is Part D IRMAA?
An income-based surcharge added to your Part D premium for higher earners, separate from the Part B IRMAA. It uses the same income thresholds and two-year lookback.
Do I pay Part D IRMAA even with a cheap drug plan?
Yes. The surcharge is based on your income, not your plan's premium, so it applies even to a $0-premium plan and to the drug coverage inside a Medicare Advantage plan.
How is the Part D surcharge billed?
It's typically paid to Medicare (often deducted from Social Security), not to your drug plan insurer — so you pay your plan its premium and Medicare the surcharge separately.
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