Prescription Drugs
Medicare Part D
Quick answer
Medicare Part D is prescription drug coverage sold by private insurance companies approved by Medicare. You get it either as a stand-alone drug plan (PDP) with Original Medicare or bundled inside most Medicare Advantage plans.
Plain-English definition
Each Part D plan has its own formulary, pharmacy network, deductible, and copay structure. Under the Inflation Reduction Act, Part D now includes an annual out-of-pocket cap.
Why it matters
Not enrolling in creditable drug coverage when first eligible creates a permanent late-enrollment penalty added to your premium.
A simple example
You take three generics and one brand. You choose the Part D plan whose formulary lists all four at the lowest tiers with a preferred pharmacy nearby.
Common mistakes & misconceptions
- Skipping Part D because you don't take medications today — the penalty is lifelong.
- Ignoring preferred pharmacies — the same tier can cost far less at one.
Related terms
Formulary
A formulary is the official list of prescription drugs a Medicare Part D or Medicare Advantage plan covers, organized by tier. Every plan has its own formulary, and the same drug can be a different tier from one plan to another.
IRMAA (Income-Related Monthly Adjustment Amount)
IRMAA is an income-based surcharge added to Medicare Part B and Part D premiums for higher earners. Social Security calculates it from your IRS tax return two years prior.
Medicare Advantage (Part C)
Medicare Advantage, also called Part C, is a way to receive your Medicare benefits through a private insurance plan approved by Medicare. Plans bundle Part A and Part B, usually include Part D drug coverage, and often add dental, vision, and hearing.
Medicare Part B
Medicare Part B is the medical insurance half of Original Medicare. It covers doctor visits, outpatient care, preventive screenings, mental health services, and durable medical equipment.
Prescription Drug Plan (PDP)
A Prescription Drug Plan (PDP) is a stand-alone Part D plan you add to Original Medicare (or to certain Medicare Advantage plans that don't include drug coverage).
Frequently asked questions
Do I need Part D if I don't take any medications?+
Enrolling in a low-cost plan when first eligible avoids the permanent late-enrollment penalty later.
Is there a cap on my drug costs?+
Yes. Part D now includes an annual out-of-pocket cap.
People also ask
Can I have Part D and Medicare Advantage?
Most MA plans already include Part D. Enrolling in a separate PDP will usually disenroll you from your MA plan.
Sources & references
📚 Where this information comes from
- Medicare.gov — official U.S. government site for people with Medicare ↗Primary source for benefits, enrollment periods, and plan comparison.
- CMS.gov — Centers for Medicare & Medicaid Services ↗Federal rulemaking, program updates, and official guidance.
- Social Security Administration — Medicare enrollment & premiums ↗Enrollment, premium withholding, and IRMAA determinations.
When you're ready, compare plans on your own terms
See Medicare Advantage plans from the insurance companies we represent, or walk the course with a licensed agent whenever you'd like a second set of eyes.
We help compare Medicare Advantage plans from the insurance companies we represent, and we don't offer every plan available in your area.
Medicare Caddies is an independent insurance agency. We are not affiliated with, endorsed by, or connected to the U.S. government, the federal Medicare program, or the Centers for Medicare & Medicaid Services (CMS). We help compare Medicare Advantage plans from the insurance companies we represent, and we don't offer every plan available in your area.