This article answers the question: "When Do I Enroll In Medicare?" It is a primer, reviewing the different and important enrollment dates for Medicare Parts A, B, C, D, and Medigap.  For questions, you can always call Medicare directly at 800.633.4227 (1.800.MEDICARE) or see the Medicare Resource section below.

Initial Medicare Enrollment Period

The time to start thinking about enrolling in Medicare for the first time is around your 65th birthday. The initial enrollment period is extremely important because missing the enrollment period can mean higher health insurance costs forever! Make sure to enroll in Medicare Part A and Medicare Part B  (three months
before, the month of, and three months after).

  • For example, if you were born on August 2, 1952, you would be turning 65 on August 2, 2017. Your initial enrollment window would then be between May 1st and November 30th  2017. 

One must to enroll in Medicare Part A and B in order to enroll in Medicare Advantage, Part D or Medigap / Medicare Supplement. If you require prescription drug coverage (who doesn’t), be sure to enroll for Medicare Part C / Medicare Advantage (with a drug plan) or a Part D Plan in the same initial enrollment period (the seven calendar months surrounding your 65th birthday). If you
fail to do so, you may wind up paying more for Part D Prescription coverage forever. 

  • ‍ TIP: if you are approaching your 65th birthday (enrolling for the first time): be safe and get Part A and B AND either Medicare Advantage (Part C) with a drug plan or Part D Prescription Drug Plan. Pay more now and then scale back rather than paying a penalty for enrolling late (for life).

How to Enroll in Original Medicare

To enroll in Medicare Part A and B, go to and sign up online, or visit a local social security office, or call 800.772.1213.

Subsequent Medicare Enrollment Periods

After you have initially enrolled (or if you missed your initial enrollment period), subsequent enrollment periods for Medicare are as follows: 

Medicare Part A and B | Original Medicare Enrollment Periods

  • Every year, January 1st through March 31st is the general enrollment period. Coverage would then start that July 1st.
  • Once 65 years old and enrolled in Medicare Part B, you have six months to purchase a Medigap policy.
  • Annual Election Period: October 15 – December 7 can switch to Medicare Advantage or different Prescription drug coverage plan.

Medicare Part C | Medicare Advantage Dates

  • Initial Election Period: same as above (in the seven months surrounding 65th birthday)
  • Annual Election Period: October 15 through December 7, can switch to Original Medicare or another Medicare Advantage Plan.
  • Special Dis-enrollment Period: January 1 through February 14 can leave Medicare Advantage and switch to an Original Medicare plan.

Special Enrollment Period

Once your Initial Enrollment Period ends, you may have the chance to sign up for Medicare during a Special Enrollment Period. If you're covered based on current employment, you have a Special Enrollment Period to sign up for Part A and/or Part B any time as long as you or your spouse (or family member if you're disabled) is working, and you're covered by a group health plan through the employer. 

If you (or your spouse) are currently working, and you're covered by an employer or union group health plan based on that employment, and you are turning 65, ask your employer or union benefits administrator if they require you to sign up for Medicare. If the employer doesn't require you to sign up for Medicare right away, you can sign up within the 8 month special enrollment period that starts the month after the employment ends (or the group health plan based on current employment ends, whichever comes first).

Dangers of Late Medicare Enrollment

If you fail to take Medicare when you are initially eligible (and don't have other coverage that is considered allowed by Medicare) or don't have any other coverage, you will likely face higher Medicare premiums (because penalties are assessed) when you enroll later in life. Your Part B coverage will increase by 10% per year that you failed to start Medicare Part B when you otherwise could have.

The late-enrollment Medicare penalty will not apply if you are of age and receive health insurance from you or your spouse's current employer. The penalty will apply for retiree health plans and COBRA health insurance plans.


Medicare Resources

When and How to Sign Up For Medicare Part A and Part B

When and How to Sign Up for Medicare Part C and Part D

When Can I Obtain a Medicare Advantage or Prescription Drug Plan

What Is the Difference Between Medicare and Medicaid?

Medicare 101: Medicare Basics