What is Medicare Part D?

Medicare Part D in a nutshell

Medicare Part D is the part of Medicare that helps pay for prescription drugs — both brand-name and generic medications you pick up at a pharmacy. It's optional, but most Medicare beneficiaries benefit from having it.

Part D is not run by the government directly. Instead, private insurance companies approved by Medicare offer Part D plans. You choose a plan, pay a monthly premium, and the plan helps cover your drug costs according to its formulary (drug list) and cost-sharing rules.

Who is eligible?

Anyone with Medicare Part A or Part B is eligible to enroll in a Part D plan. This includes:

• People age 65 and older with Medicare
• People under 65 with certain disabilities who have Medicare
• People with End-Stage Renal Disease (ESRD) who have Medicare

Why you should consider Part D — even if you're healthy

Even if you don't take prescription medications right now, there are important reasons to enroll in Part D when you first become eligible:

• Late enrollment penalty — if you go without Part D or other creditable drug coverage and enroll later, you'll pay a permanent penalty added to your premium. Learn about the penalty →
• Protection against unexpected costs — a single new prescription can cost hundreds or thousands per month without coverage
• Low-cost options exist — some Part D plans have premiums as low as $0 per month

What Part D covers

Part D plans cover a wide range of prescription drugs, including:

• Generic and brand-name medications
• Insulin (capped at $35/month)
• Vaccines recommended by the Advisory Committee on Immunization Practices (ACIP)
• Some specialty medications

Each plan has its own formulary (list of covered drugs). Not every drug is covered by every plan, which is why it's important to check that your medications are on a plan's formulary before enrolling.

Full guide to what Part D covers →

Learn how Part D coverage works →