Two Income-Related Adjustments
Part B vs. Part D IRMAA: How Medicare’s Two Surcharges Work
Part B and Part D IRMAA use the same income information, but they attach to different parts of Medicare. One raises the Part B premium; the other is paid in addition to the premium for prescription coverage.
Quick answer
Part B IRMAA Raises Part B; Part D IRMAA Sits Beside the Drug-Plan Premium
When IRMAA applies, the Part B adjustment is included in the beneficiary’s total monthly Part B premium. Part D IRMAA is a separate amount owed to Medicare in addition to the premium charged for prescription drug coverage.
Choosing a different Medicare Advantage, Part D or Medicare Supplement plan does not by itself remove either adjustment. Social Security determines IRMAA from tax information.
Part B and Part D IRMAA Compared
Part B IRMAA
Added to the Medical Insurance Premium
Every person enrolled in Part B owes the applicable Part B premium. When IRMAA applies, the income-related amount increases the total Part B premium for that beneficiary.
Part D IRMAA
Added to Prescription Coverage Cost
A beneficiary with Medicare drug coverage can owe Part D IRMAA in addition to the plan premium. This includes Part D built into a Medicare Advantage plan.
| Question | Part B IRMAA | Part D IRMAA |
|---|---|---|
| What does it attach to? | Medicare Part B medical insurance | Medicare prescription drug coverage |
| Who determines it? | Social Security | Social Security |
| What income is used? | Generally the same MAGI and tax filing status from two years earlier | Generally the same MAGI and tax filing status from two years earlier |
| Who receives the payment? | Medicare, often through a benefit deduction or Medicare bill | Medicare—not the prescription plan—even though it relates to Part D |
| Does a $0-premium plan erase it? | No | No |
| Can Medicare Advantage avoid it? | No | No, when the plan includes Part D and the beneficiary owes IRMAA |
2026 example
How the Two Adjustments Appear in the Same Income Tier
For 2026, an individual with 2024 MAGI above $137,000 through $171,000—or a married couple filing jointly with MAGI above $274,000 through $342,000—falls in the second IRMAA level.
- Part B: The total 2026 Part B premium is $405.80 per month for each affected beneficiary.
- Part D: The beneficiary owes $37.50 per month in Part D IRMAA in addition to the prescription plan’s premium.
If both spouses are enrolled in Part B and Part D, each can owe their own adjustment even though the same joint return established the household’s income tier.
How IRMAA Is Usually Collected
When a beneficiary receives Social Security or Railroad Retirement benefits, Medicare premiums and applicable IRMAA amounts are often withheld from the monthly benefit. When they are not withheld, Medicare may send a premium bill.
Part D IRMAA is not normally paid to the insurance company. It is owed to Medicare in addition to the plan premium. A beneficiary should follow the billing instructions received from Social Security, Medicare or the Railroad Retirement Board.
How Medicare Advantage Changes—and Does Not Change—the Picture
Medicare Advantage replaces how a beneficiary receives Part A and Part B services, but it does not eliminate the requirement to have Part B and pay the applicable Part B premium. Therefore:
- Part B IRMAA can apply to a Medicare Advantage enrollee.
- If the Medicare Advantage plan includes Part D, Part D IRMAA can also apply.
- A plan’s Part B premium reduction benefit does not change Social Security’s IRMAA determination.
- Part D IRMAA remains owed to Medicare rather than to the Medicare Advantage carrier.
What About Original Medicare and Medigap?
A person using Original Medicare with a Medicare Supplement policy still pays the applicable Part B premium, including Part B IRMAA. The Medigap premium is a separate private-policy cost.
If that person also has a stand-alone Part D plan, Part D IRMAA may be owed in addition to the plan’s premium. Changing Medigap companies does not change IRMAA.
The Income Calculation Is Shared
Both adjustments generally use the same Medicare MAGI: adjusted gross income plus tax-exempt interest. Social Security usually looks back two years. Read what counts as income for Medicare IRMAA and the broader 2026 IRMAA explainer for the thresholds and timing.
If income fell after retirement or another recognized life-changing event, the beneficiary may be able to request a new determination using more recent information. See our SSA-44 guide.
Frequently asked questions
Part B and Part D IRMAA Questions
Can I owe Part B IRMAA but not Part D IRMAA?
Yes. A person enrolled in Part B but without Medicare prescription drug coverage would not owe a Part D adjustment for that period. When a beneficiary has both Part B and Part D and exceeds the income threshold, both adjustments generally apply.
Does a $0-premium Medicare Advantage plan eliminate IRMAA?
No. The plan’s premium is separate from the Part B premium and any Part B or Part D IRMAA owed to Medicare.
Is Part D IRMAA paid to my insurance carrier?
No. Part D IRMAA is generally paid to Medicare, often through a benefit deduction or separate Medicare billing, in addition to any premium owed to the plan.
Can my Medicare broker remove IRMAA?
No. Social Security makes IRMAA decisions. A broker can explain how the amount fits into the total Medicare cost and help compare private plan options.
Are the Part B and Part D brackets different?
They generally use the same MAGI tiers and filing-status thresholds for the premium year, but each tier produces a different Part B and Part D dollar adjustment.
Medicare premiums and IRMAA series
Continue the IRMAA Guide Series
Official information
Medicare and Social Security Resources
Compare the complete cost
Include Part B, Part D and IRMAA in Your Plan Review
Thompson Medicare Brokerage helps people in Missouri and Illinois compare the private Medicare coverage options we represent while accounting for the Medicare premiums that exist outside the plan.
Social Security makes IRMAA determinations. We can help you understand how those amounts fit beside Medicare Advantage, Part D or Medicare Supplement costs.
This article provides general Medicare information and does not provide tax, investment, accounting or legal advice. Premiums and thresholds change annually. Social Security and Medicare make official determinations.