Learn more about Medicare Part A and Part B enrollment.

Initial Enrollment Period

Late Enrollment and Changes to Medicare Coverage

Initial Enrollment Period

The Initial Enrollment Period is a limited window of time when you can enroll in Original Medicare (Part A and/or Part B) when you are first eligible. After you are enrolled in Medicare Parts A and B you can, if interested, select other coverage options (e.g. Medicare Advantage, Medigap, Part D, etc.) from approved private insurers.

When to Enroll

When you are first eligible, your Initial Enrollment Period for Medicare Part A and Part B lasts seven months and starts when you qualify for Medicare, either based on your age or an eligible disability.

Individuals Aged 65 or Older

Your Initial Enrollment Period is based on the month in which you turn 65. It begins three months before your birth month and extends until three months after your birth month.

Graphic demonstrating the 7 month window for the Initial Enrollment Period

Example: If you are born on June 18, 1952, your Initial Enrollment Period is from March 1, 2017 until September 30, 2017.

Individuals Aged Under 65 with an Eligible Disability

Your Initial Enrollment Period is based on when you began receiving Social Security or Railroad Retirement Board (RRB) disability benefits. It begins the 22nd month after you began receiving benefits and continues until the 28th month after you began receiving benefits.

Graphic demonstrating the 7 month window for the Initial Enrollment Period

Example: If you are began receiving disability benefits in January 2015, your Initial Enrollment Period is from November 1, 2016 until May 31, 2017.

How to Enroll

If you already receive Social Security or certain retirement benefits, you may be automatically enrolled in Original Medicare during this time period. Otherwise, you will need to sign up manually through the U.S. Social Security Administration.

Automatic Enrollment

You will be automatically enrolled in Medicare Part A and Part B if you reach age 65 and receive Social Security or Railroad Retirement Board (RRB) retirement benefits. You will also be automatically enrolled if you are under age 65 with an eligible disability.

You will receive a Medicare card in the mail three months before your 65th birthday or your 25th month of disability. It will include instructions for opting out of enrollment for Part B, should you wish to do so.

Manual Enrollment

You can apply for Medicare Part A and Part B under certain conditions:

  • You are eligible for Social Security or Railroad Retirement Board (RRB) benefits, but don’t receive them.
  • You qualify for Medicare due to End-Stage Renal Disease (ESRD).
  • You don’t qualify for premium-free Part A coverage.

Note: If you live in Puerto Rico and receive Social Security benefits, you will automatically be enrolled in Part A. However, you will need to apply for enrollment in Part B.

Choosing Other Medicare Coverage

After you enroll in Medicare Part A and Part B, you can choose a Medicare coverage option (such as a Medicare Advantage plan). You can change your coverage later, during the annual Open Enrollment Period. However, if you enroll in a Prescription Drug Coverage (Medicare D) coverage after your Initial Enrollment Period, a late enrollment penalty may be added to your premium.

Learn More

Late Enrollment and Changes to Medicare Coverage

Your Initial Enrollment Period provides a limited time window to enroll in Medicare Part A and Part B (Original Medicare). If you miss this enrollment period you can still enroll later, but you must manually apply for Medicare A and B, and some penalties may apply. There is no automatic enrollment outside of your Initial Enrollment Period.

Open Enrollment Period

October 15 through December 7

The Medicare Open Enrollment Period provides an annual opportunity to review, and if necessary, change your Medicare coverage options.  Coverage becomes effective on January 1. During Open Enrollment, some examples of changes that you can make include:

  • Join a Medicare Advantage (Part C) plan.
  • Discontinue your Medicare Advantage plan and return to Original Medicare (Part A and Part B).
  • Change from one Medicare Advantage plan to another.
  • Add or Change your Prescription Drug Coverage (Part D) plan if you are in Original Medicare.

General Enrollment Period

January 1 through March 31

The General Enrollment period offers an annual opportunity to enroll in Medicare Part A and/or Part B.  If you enroll in Medicare during the General Enrollment Period, your coverage starts July 1. For example, you can:

  • Sign up for Original Medicare if you weren’t automatically enrolled and missed your Initial Enrollment Period.
  • Enroll in Part B if you have opted out of automatic enrollment or dropped your coverage.

If you enroll in Part B after your Initial Enrollment Period, then you will spend more on your premium, unless you qualify for a Special Enrollment Period.

Special Enrollment Period

There are certain situations that may allow you to enroll in the Medicare program or Medicare options outside of the Initial and annual Open Enrollment Periods. 

If you have coverage through your employer and that coverage terminates, you may be eligible for a Special Enrollment Period. 

More information about Special Enrollment Periods is available on the Social Security website.

Medicare overview information on this website was developed by the Blue Cross and Blue Shield Association to help consumers understand certain aspects about Medicare. Viewing this Medicare overview does not require you to enroll in any Blue Cross Blue Shield plans. To find out about premiums and terms for these and other insurance options, how to apply for coverage, and for much more information, contact your local Blue Cross Blue Shield company. Each Blue Cross Blue Shield company is responsible for the information that it provides. For more information about Medicare including a complete listing of plans available in your service area, please contact the Medicare program at 1-800-MEDICARE (TTY users should call 1-877-486-2048) or visit www.medicare.gov.

Medicare has neither reviewed nor endorsed this information.

The Blue Cross Blue Shield Association is an association of 36 independent, locally operated Blue Cross and/or Blue Shield companies.