Medicare Part D
Why some Mount Pleasant retirees pay more for Medicare Part B and D
Mount Pleasant, S.C. — As Medicare's Annual Enrollment Period runs through Dec. 7, many South Carolina retirees are opening letters from Social Security that mention something called IRMAA. If you've never seen the term before, it can be jarring. Here's what it means for your 2027 Part B and Part D costs, and how to avoid a surprise you didn't see coming.
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Key takeaways
- IRMAA is an extra charge added to Part B and Part D premiums for people whose income is above a certain level, based on tax returns from two years earlier, so 2027 premiums are based on 2025 income.
- For 2026, the surcharge starts once income crosses $109,000 for a single filer, or roughly double that for a married couple filing jointly, with higher tiers costing more.
- If income has dropped due to a life-changing event, beneficiaries can file form SSA-44 with documentation to ask Social Security to reconsider the surcharge.
- Switching Part D plans during Annual Enrollment (Oct. 15 – Dec. 7) won't lower or remove IRMAA, since it's based on income rather than which plan is chosen.
What IRMAA actually is
IRMAA stands for the Income-Related Monthly Adjustment Amount. It's an extra charge added to your Medicare Part B (doctor visits and outpatient care) and Part D (prescription drug) premiums if your income is above a certain level.
Most people don't pay it. According to Medicare, only a small share of beneficiaries have income high enough to trigger the surcharge. But if you do, it's added on top of the standard premium you'd otherwise pay.
One important detail: IRMAA is not based on your income today. Social Security looks at your tax return from two years ago. So your 2027 Medicare premiums are based on your 2025 tax return.
The 2027 income thresholds
For 2026, IRMAA starts once your modified adjusted gross income (MAGI) crosses $109,000 for a single filer or roughly double that for a married couple filing jointly. Below that line, you pay the standard Part B premium and no Part D surcharge.
Above that line, there are several tiers. The higher your income, the higher the surcharge — for both Part B and Part D. At the top tier, the total monthly cost can be several times the standard premium.
The exact tier amounts are published each year by the Centers for Medicare & Medicaid Services (CMS) at medicare.gov. It's worth checking the current chart before you assume you'll owe a surcharge — the brackets shift a little each year with inflation.
How the surcharge shows up
If you owe IRMAA, Social Security will mail you a determination letter, usually late in the year. The Part B portion is deducted from your Social Security check (or billed directly if you're not yet drawing benefits). The Part D portion is billed separately by Medicare — even if your drug plan premium is otherwise paid another way.
That last point trips people up. You can be enrolled in a Part D plan through a private insurer, but the IRMAA surcharge comes from Medicare itself. Missing those bills can put your coverage at risk.
Life changes can lower what you owe
Because IRMAA looks back two years, it doesn't always reflect what's happening now. If you've had a major life event that reduced your income, you can ask Social Security to reconsider.
Qualifying events include:
- Retirement or reduced work hours
- Death of a spouse
- Divorce or marriage
- Loss of a pension
- Loss of income-producing property (not from your own sale)
The form is SSA-44, "Medicare Income-Related Monthly Adjustment Amount – Life-Changing Event." You'll need documentation, like a letter from a former employer or a death certificate. This is the single most common way people in the Mount Pleasant area lower an IRMAA bill they shouldn't be paying.
What this has to do with AEP
Mount Pleasant is in Charleston County, where beneficiaries have a range of stand-alone Part D plans and Medicare Advantage plans with drug coverage to choose from during Annual Enrollment (Oct. 15 – Dec. 7).
Here's the catch: IRMAA follows you regardless of which plan you pick. Switching Part D plans won't reduce or eliminate the surcharge, because the surcharge is based on your income, not your plan's premium. What changing plans can do is affect the base premium, deductible (the Part D maximum deductible is $615 in 2026 and $700 in 2027), and how your drugs are covered under the annual out-of-pocket cap, which is $2,100 in 2026 and $2,400 in 2027.
If drug costs are still hard to manage month-to-month, ask about the Medicare Prescription Payment Plan, a new option that spreads your out-of-pocket drug costs across the calendar year instead of hitting all at once at the pharmacy counter.
Mistakes to avoid
- Assuming your premium is wrong. If your income two years ago was high — even from a one-time event like selling a house — IRMAA can look like a billing error. It usually isn't.
- Ignoring the appeal option. If your income has genuinely dropped, don't just pay. File Form SSA-44.
- Forgetting the Part D piece. The Part D surcharge is separate and easy to miss until a bill arrives.
- Waiting to check the numbers. The 2026 brackets are already published on medicare.gov.
By the numbers
Medicare Part B premium, 2006–2026
The standard monthly Part B premium has climbed from $88.50 in 2006 to $202.90 in 2026. Hover any point for that year’s premium.
Source: CMS. Standard premium shown; in some hold-harmless years many existing enrollees paid less. Confirm at Medicare.gov.
By the numbers
How people get Medicare in Charleston County
(MA penetration in Charleston County)
MA penetration from CMS enrollment data; Medigap share is an estimate. U.S. average is about 54% Medicare Advantage. These are area-level figures, not plan-specific.
Higher-income surcharges
IRMAA income brackets: what to watch for
If your income is above a threshold, you pay an income-related surcharge (IRMAA) on top of your Part B and Part D premiums. Your 2026 surcharge is based on your 2024 tax return.
| Income — single filer | Income — married, joint | Part B monthly premium | Part D surcharge |
|---|---|---|---|
| $109,000 or less | $218,000 or less | $202.90 | Plan premium only |
| $109,001 – $137,000 | $218,001 – $274,000 | $284.10 | + $14.50 |
| $137,001 – $171,000 | $274,001 – $342,000 | $405.80 | + $37.40 |
| $171,001 – $205,000 | $342,001 – $410,000 | $527.50 | + $60.40 |
| $205,001 – $500,000 | $410,001 – $750,000 | $649.30 | + $83.30 |
| Above $500,000 | Above $750,000 | $689.90 | + $91.00 |
Standard Part B premium is $202.90/month. Part D surcharges are added to your drug plan’s premium. Married-filing-separately uses a different, compressed schedule. Confirm current amounts at Medicare.gov.
Try it
Find your 2026 Medicare premium
Most people pay the standard Part B premium. If your 2024 income was higher, an income-related surcharge (IRMAA) applies. Enter your details to see your bracket.
Surcharges are added to your premiums and based on your 2024 tax return. Married-filing-separately uses a different schedule. Confirm at Medicare.gov.
Try it
How the 2026 Part D drug cap works
Slide to your estimated yearly prescription costs and see how the new $2,100 out-of-pocket cap protects you. This illustrates the standard Part D benefit; your plan may structure costs differently.
Once your out-of-pocket spending on covered drugs reaches $2,100, you pay nothing more for the rest of 2026. Confirm details at Medicare.gov.
Good to know
Frequently asked questions
Does IRMAA apply if I have Medicare Advantage instead of Original Medicare?
My income last year was much lower than 2024. Do I have to wait for it to catch up?
Is IRMAA permanent?
- CMS — Medicare costs & IRMAA (medicare.gov)
For personalized answers, contact Medicare.gov, 1-800-MEDICARE, or your local SHIP.