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How to enroll in Medicare Part D

When to enroll, how to sign up, and what happens if you miss the deadline — everything you need to know in plain language.

When can you enroll?

You can only enroll in or change Part D plans during specific enrollment periods. Missing these windows can result in a permanent late enrollment penalty, so it's important to know your dates.

Initial Enrollment Period (IEP)

When you first become eligible for Medicare — typically around your 65th birthday — you have a 7-month window to enroll. This period starts 3 months before your birthday month, includes your birthday month, and ends 3 months after.

Don't miss your Initial Enrollment Period

If you don't enroll during your IEP and don't have other creditable drug coverage, you'll face a permanent late enrollment penalty added to your premium for as long as you have Part D. Learn about the penalty →

Annual Open Enrollment (AEP)

October 15 – December 7 each year. During this period, anyone with Medicare can join, switch, or drop a Part D plan. Coverage begins January 1 of the following year. This is also the time to review your current plan — formularies, premiums, and pharmacy networks can change from year to year.

Special Enrollment Periods (SEPs)

Certain life events qualify you to enroll or change plans outside the normal windows:

  • You move to an area where your current plan isn't available
  • You lose creditable drug coverage (e.g., from an employer)
  • You qualify for Extra Help (low-income subsidy)
  • You enter or leave a nursing home
  • Your plan's contract with Medicare is terminated

Full guide to enrollment periods →

How to enroll

There are several ways to enroll in a Part D plan:

  1. Online — through Medicare.gov or the plan's website
  2. By phone — call 1-800-MEDICARE (1-800-633-4227) or the plan directly
  3. Through an agent — a licensed Local Medicare Agent can walk you through your options and handle the paperwork at no cost to you
  4. By mail — complete a paper enrollment form

What you'll need

Have the following information ready when you enroll:

  • Your Medicare number (from your red, white, and blue Medicare card)
  • The date your Medicare Part A and/or Part B coverage started
  • A list of your current prescription medications and dosages

After you enroll

Once enrolled, you'll receive a membership card from your plan. This is what you'll present at the pharmacy. You'll also receive an Evidence of Coverage document and a formulary (drug list) — keep both for reference.