Prescription Drug Coverage (Part D)
Standalone drug coverage tailored to the medications you take
Overview
Medicare Part D covers prescription drugs. You can enroll in a standalone Medicare drug plan alongside Original Medicare (and, in some cases, certain Medicare Cost, Private Fee-for-Service, or MSA plans), or get Part D built into a Medicare Advantage plan. You must have Part A and/or Part B to join a separate Medicare drug plan.
What Medicare Part D is
Part D is Medicare's prescription drug coverage. It's sold by private insurance carriers approved by Medicare & can be purchased two different ways: as a standalone drug plan (PDP) that sits next to Original Medicare or a Medigap policy, or built into a Medicare Advantage plan (MAPD).
Each Part D plan publishes a formulary — the list of covered drugs & their tiers — that resets every January 1. Reviewing your plan each year during Annual Enrollment is essential, because a medication that was low-cost this year may move tiers or leave the formulary next year.
What Part D covers
- Generic medications — usually the lowest-cost tier on the formulary
- Preferred & non-preferred brand-name drugs
- Specialty medications used to treat complex conditions
- ACIP-recommended adult vaccines at $0 cost-share
How the 2026 standard benefit works
Part D coverage moves through three stages each calendar year:
- Stage 1 — Deductible: plans may set a deductible up to $615. You pay 100% of covered drug costs until the deductible is met. Some plans have a $0 deductible or exclude Tiers 1 & 2.
- Stage 2 — Initial Coverage: you pay up to 25% coinsurance on covered drugs until you reach the $2,100 out-of-pocket maximum. Any deductible you paid counts toward this cap.
- Stage 3 — Catastrophic Coverage: once you hit the $2,100 out-of-pocket cap, you pay $0 for covered Part D prescriptions for the rest of the year.
Who is eligible
- Anyone enrolled in Medicare Part A and/or Part B
- Original Medicare or Medigap members who need drug coverage
- People currently taking prescription medications
- Lower-income beneficiaries who qualify for Extra Help / the Low-Income Subsidy
Why someone chooses Part D
Without Part D, Medicare pays almost nothing toward your prescriptions. Enrolling on time locks in a plan tailored to your medications, protects you from unlimited out-of-pocket drug spending thanks to the new $2,100 annual cap, & avoids the 1%-per-month late-enrollment penalty that stays with you for life.
Important benefits & limitations
- 2026 national base Part D premium is $38.99; higher-income beneficiaries also pay a Part D IRMAA
- The $2,100 out-of-pocket maximum resets every January 1
- Formularies, tiers, & preferred pharmacies can change each year
- You generally can't have both a Medicare Advantage plan with drug coverage (MAPD) & a standalone Part D plan
- Late-enrollment penalty is 1% of the national base premium for every month you were eligible without creditable drug coverage — & it lasts as long as you have Part D
IRMAA on Part D
Higher-income beneficiaries pay a Part D IRMAA on top of their plan premium — from $14.50 up to $91.00 per month in 2026, based on 2024 income. The Part D IRMAA is billed directly by Medicare & must be paid even if a third party pays your plan premium.
Key highlights
- 2026 national base Part D premium: $38.99
- 2026 maximum annual deductible: $615
- Annual out-of-pocket maximum threshold of $2,100 on covered drugs
- $0 cost-sharing after you reach the out-of-pocket maximum (Catastrophic Coverage)
- Formularies, deductibles, & tiers reset every January 1
- Extra Help / Low-Income Subsidy available for qualifying incomes
What it covers
Generic medications
Typically the lowest-cost tier on the plan's formulary.
Brand-name drugs
Preferred & non-preferred brand tiers.
Specialty medications
High-cost drugs for complex conditions.
Vaccines
ACIP-recommended adult vaccines at $0 cost-share.
2026 Part D — three-stage standard benefit
| Stage | What happens | What you pay |
|---|---|---|
| Stage 1 — Deductible | Plans may set a deductible up to $615 (some plans have $0, others exclude Tiers 1 & 2) | 100% of gross covered prescription costs until the deductible is met |
| Stage 2 — Initial Coverage | Ends when you reach the $2,100 out-of-pocket maximum. Any deductible you paid counts toward this cap. | Up to 25% coinsurance for covered Part D drugs |
| Stage 3 — Catastrophic Coverage | You've hit the $2,100 out-of-pocket max | $0 for covered Part D prescriptions |
All contributions toward the maximum threshold reset on January 1 each year. Part D premiums (including any IRMAA) are separate from these cost-sharing amounts & must be paid directly to Medicare when IRMAA applies. 2026 standard-benefit parameters ($615 maximum deductible, $2,100 out-of-pocket threshold) are set by CMS; for 2027 CMS has announced a $700 maximum deductible & a $2,400 out-of-pocket threshold.
IRMAA on Part D
Higher-income beneficiaries pay a Part D IRMAA on top of their plan premium — from $14.50 up to $91.00 per month in 2026, based on 2024 income. Unlike Part B IRMAA (which is added to your monthly bill), the Part D IRMAA is billed directly by Medicare & must be paid even if a third party pays your plan premium.
Frequently asked questions
What's the Part D out-of-pocket cap?+
Once you spend $2,100 out of pocket on covered Part D drugs in a calendar year, you pay $0 for the rest of the calendar year (Catastrophic Coverage).
Can I change my plan each year?+
Yes — during Annual Enrollment (October 15 – December 7) you can switch Part D plans for the following year. Formularies change each year, so an annual review is essential.
What if I already have Medicare Advantage?+
Most Medicare Advantage plans include Part D (MAPD). If yours does, you don't need — & generally can't have — a separate standalone Part D plan.
Do I need Part D right away?+
If you don't enroll when first eligible & don't have other creditable drug coverage, you'll pay a 1%-per-month late-enrollment penalty for as long as you have Part D.
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