Your opportunity to enroll in the different Medicare plans depends on several factors. Below is a summary of the various enrollment dates for Original Medicare Parts A and B, Medicare Advantage plans and Medicare Supplement plans. Review this information to help you better understand when the best time is to enroll in the right Medicare plan for you.

Initial Enrollment Period for Original Medicare and Medicare Advantage

If you’re 65 or about to turn 65, you’re eligible for Original Medicare during your Initial Enrollment Period. This seven-month period includes:

  • The three months before your birth month
  • Your birth month
  • The three months after your birthday month

During this time, you can apply for a Medicare Advantage plan if your Original Medicare Part A or B coverage has started and you are paying your Part B premium.

Medicare Supplement Open Enrollment

The best time to buy a Medicare Supplement plan is during your initial six-month open enrollment period. This period starts the first day of the month you turn 65 years old and are enrolled in both Medicare Parts A and B. It's important to remember that Medicare Supplement's open enrollment period is different than Medicare Advantage's initial enrollment period.

During the open enrollment period, you can buy any Medicare Supplement insurance policy your state offers. Once you're enrolled, you're automatically guaranteed to be renewed each year, regardless of your health status, (as long as you pay your premiums).

Medicare Open Enrollment: Annual Enrollment Period

If you are enrolled in Original Medicare, a Medicare Advantage plan or a stand-alone Part D plan, you may change or add plans from October 15 through December 7 each year.  This is known as the Annual Enrollment or Annual Election Period (AEP). With a few exceptions, this is the only time you may add or switch Medicare Advantage or stand-alone Part D plans and the new coverage you enroll in during this period will begin January 1.

Special Enrollment Period

Enrolling in Original Medicare at a Later Retirement Age

If you are employed and covered by your employer’s health plan when you turn 65, you don’t have to enroll in Original Medicare during your Initial Enrollment Period. You can enroll when that employment or coverage ends without incurring a penalty. This Special Enrollment Period runs for eight months after the employment or health insurance ends, whichever comes first. If your employer has fewer than 20 employees, the rules may be different. Contact your plan administrator for more details. Once you are enrolled in Original Medicare, you can enroll in a Medicare Advantage Plan during this Special Enrollment Period.

Special Enrollment Period for Medicare Advantage

There are additional specific circumstances that let you enroll in a Medicare Advantage plan at any time. Examples that may qualify you for special enrollment include, but are not limited to:

  • You were enrolled in a plan but moved out of the plan’s service area
  • You are eligible for both Medicare and Medicaid
  • You entered a nursing home or facility
  • You meet low income requirements
  • You have left an employer group health plan

Enrolling in Original Medicare at a Later Retirement Age

If you are employed and covered by your employer’s health plan when you turn 65, you don’t have to enroll in Original Medicare during your Initial Enrollment Period. In this case, you are eligible to enroll at a later age. When you retire, you have eight months to enroll in Original Medicare – after your employment ends or after your group coverage ends, whichever comes first. Once you are enrolled in original Medicare, you can enroll in a Medicare Advantage plan during the Special Enrollment Period.

General Enrollment Period for Original Medicare and Medicare Advantage

If you miss your Initial Enrollment Period for Original Medicare and are NOT eligible for a Special Enrollment Period described above, you can still enroll during the next General Enrollment Period, which occurs from January 1 to March 31 each year. Your coverage will start July 1 of that year and you may have to pay a higher premium for late enrollment in Medicare Part A and/or Medicare Part B.

If you enroll in Original Medicare during the General Enrollment Period, you are eligible to enroll in a Medicare Advantage plan or a Medicare prescription drug plan (Part D) from April 1 - June 30 of the same year.


Have a Question? We Can Help!

Speak with a Medical Mutual licensed insurance agent or call your insurance agent.

Call (866) 406-8777 (TTY 711 for hearing impaired)

Mon.-Fri. 8 a.m. to 8 p.m.

Page last updated on 2/17/2017
H4497_H6723_WS_2016_Jun15 CMS Approved
C1757-MCS R1/16