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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 →

Free help choosing the right plan to enroll in

Before you enroll, make sure you've compared plans for your specific medications. The Medicare.gov Plan Finder is the official tool, and PlanMatch offers an alternative comparison tool. Licensed Medicare agents can also run comparisons for you and explain the tradeoffs at no cost.

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.