Understanding Medicare enrollment periods

Figuring out when you can sign up for Medicare or switch Medicare health plans can feel a little confusing. That’s because Medicare has several “parts,” each with its own sign-up rules. Plus, there are a few different enrollment windows to keep in mind.

There are 6 main sign-up periods for Medicare:

Initial enrollment
General enrollment
Special enrollment
Annual open enrollment
Medicare Advantage open enrollment
5-star special enrollment

Enrollment dates at a glance

Here’s a quick look at enrollment periods, deadlines, and what you can do.

Enrollment period	When it happens	What you can do
Initial enrollment period	It’s a 7-month window tied to your 65th birthday. It starts 3 months before and ends 3 months after the month you turn 65.	Enroll in Medicare Parts A and B (Original Medicare). After you’re enrolled in Parts A and B, you can enroll in optional Part C or Part D coverage.
General enrollment period	If you miss your initial enrollment period, you can sign up between January 1 and March 31 each year.	Enroll in Medicare Parts A and B (Original Medicare). After you’re enrolled in Parts A and B, you can enroll in optional Part C or Part D coverage.
Special enrollment period	The time frame varies and is based on your qualifying special circumstance.	Enroll in a Medicare Advantage plan or switch from one Medicare Advantage plan to another.
Annual open enrollment period	Happens each year between October 15 and December 7.	Make changes to your Medicare plan, such as switching from Original Medicare to a Medicare Advantage plan or joining a Part D plan.
Medicare Advantage open enrollment period	Happens each year between January 1 and March 31.	Switch from one Medicare Advantage plan to another, or switch from a Medicare Advantage plan to Original Medicare (Parts A and B).
5-star special enrollment period	Happens each year between December 8 and November 30. Applies to plans for the year that get a 5-out-of-5-Star rating from the Centers for Medicare & Medicaid Services (CMS).	Switch to a 5-Star Medicare Advantage plan.

Overview of enrollment dates

Here’s a detailed breakdown of each enrollment period to help make sense of it all.

Initial enrollment period for Part A and Part B

It all starts with your initial enrollment period. This is the first time you can sign up for Medicare Part A and Part B because of your age. This deadline is specific to you because it’s centered around your 65th birthday. The initial enrollment period lasts 7 months — it starts 3 months before and ends 3 months after the month you turn 65.

You’ll need to have Part A and Part B (Original Medicare) before you can get Part C (Medicare Advantage). You’ll need Part A, Part B, or both before you can get Part D.

If you enroll in Medicare Part B or Part D after your 7-month initial enrollment period, you may have to pay a late enrollment penalty.

General enrollment period for Part A and Part B

If you missed your initial enrollment period and didn’t enroll in Medicare, you can sign up for Medicare Parts A and B during the general enrollment period. This enrollment window is January 1 through March 31 each year, for coverage starting on July 1.

Special enrollment periods for Part A and Part B

Once your initial enrollment period ends, you may have the chance to sign up for Medicare Parts A and B during a special enrollment period. This is a special circumstance — like retiring after age 65, or losing coverage through your employer — that allows you to sign up for Medicare at various times throughout the year.

Special enrollment periods for Part C

You may qualify for a special enrollment period if any of these situations apply:

You recently moved to an area that isn’t served by your Medicare health plan.
You’re eligible for both Medicare and Medicaid (Medi-Cal in California), in which case you may qualify for a Special Needs Plan. If you qualify, you can enroll at any time.
You had a Special Needs Plan, but recently lost eligibility for it.
You’re eligible for Medicare and Medicaid (Medi-Cal in California) or you recently lost eligibility.
You qualify for Extra Help to pay for your prescription drug costs or you recently lost eligibility.
You’ll soon be enrolling in, are currently enrolled in, or recently left a health plan offered through an employer.
You recently lost prescription drug coverage from an approved plan (other than Medicare).
You currently live in or recently left a nursing home.

Annual open enrollment period

You can join a Medicare health plan, switch plans, or drop a plan during the annual open enrollment period. This happens each year between October 15 and December 7. This is your chance to make changes. For example, you can:

Switch from Original Medicare to a Medicare Advantage (Part C) plan
Join, change, or drop a Medicare Advantage plan
Join, change, or drop a Medicare Part D prescription drug plan
Join a Medicare Cost plan with a Part D prescription drug plan
Add a Part D drug plan to a Medicare Cost plan that you’re already enrolled in

Changes made during the annual open enrollment period take effect on January 1 of the next year.

Medicare Advantage open enrollment period

If you’re already enrolled in Medicare Part C, you can switch plans during the Medicare Advantage open enrollment period. This sign-up window happens each year from January 1 to March 31. You can switch to a different Medicare Advantage plan or switch to Original Medicare (Parts A and B) plus a separate Part D drug plan. You can make a change one time during this enrollment period.

5-star special enrollment period for Part C and Part D

Every year, CMS gives out star quality ratings. They rate Medicare Advantage plans and Medicare Part D drug plans nationwide. If a plan for the year is rated 5 out of 5 Stars, you can switch to that plan before the next annual open enrollment period. This sign-up period is December 8 to November 30 each year. The 5-star special enrollment period lets you make one change during this time.