Eligibility for Medicare

You are generally entitled to Medicare if you meet any of the following criteria: 

  • You are age 65 or above.
  • You already receive Social Security or Railroad Retirement Board (RRB) benefits.
  • You have been diagnosed with end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS, “Lou Gehrig’s disease”).

Enrolling in Medicare

Learn more about the timeframes for Medicare enrollment.

Initial Enrollment Period

Your Initial Enrollment Period is when you first become eligible for Medicare. This is a seven-month window when you can enroll in Original Medicare (Part A and/or Part B). You can also enroll in a Medicare Prescription Drug (Part D) plan if you are already enrolled in Original Medicare.

Alternatively, you can choose a Medicare Advantage plan through a private insurer that covers all Parts A and B services and typically includes Medicare Prescription Drug (Part D) coverage. 

Once your Initial Enrollment Period has ended, you can only make enrollment changes during either the Medicare Open Enrollment Period or General Enrollment Period, unless you qualify for a Special Enrollment Period.

Open Enrollment Period

October 15 through December 7

The Medicare Open Enrollment Period provides an annual opportunity to review and, if necessary, make enrollment changes to your Medicare coverage. During Open Enrollment, some examples of changes that you can make include:

  • Join a Medicare Advantage (Part C) plan.
  • Discontinue your Medicare Advantage coverage and return to Original Medicare.
  • Change from one Medicare Advantage plan to another.
  • 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 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.

During the General Enrollment Period, 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 had opted out of automatic enrollment, didn’t enroll or dropped your coverage.

If you enroll in Part B after your Initial Enrollment Period, you will pay a penalty added to your monthly Part B premium.

Special Enrollment Periods

There are certain situations when you can enroll in the Medicare program or other Medicare options, outside of the Initial or annual Open Enrollment Periods. For example, if you have health coverage through your employer that is terminated, you may be eligible for a Special Enrollment Period where you could enroll in Part B, as well as other Medicare options, such as Medicare Advantage.

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

More Enrollment Details

Medicare has different parts (referred to as Parts A, B, C and D) designed to address your healthcare needs. Learn more about enrollment for:

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.