When is the best time to enroll in Medicare?

  • By
  • medicareresources.org Contributor
  • March 5, 2018

Q: When is the best time to enroll in Medicare?

A: The best time to enroll is during the open enrollment window around your 65th birthday – preferably in the three months before the month you turn 65, so that you’ll have Medicare coverage by the time you turn 65.

Your open enrollment window for Medicare A and B is seven months long, and includes the month you turn 65 as well as the three months prior to that month, and the three months after. EXAMPLE: If your birthday is April 22, your open enrollment window runs from the beginning of January to the end of July.

If you enroll during the three-month window before the month you turn 65, your coverage will take effect on the first of the month that you turn 65. (If your birthday is the first of the month, your coverage takes effect the first of the month before your birthday, as long as you enrolled prior to that.) So for the example above, if you enroll during January, February, or March, Medicare coverage will be effective on April 1.

Reasons to not wait

You can wait and enroll during the month you turn 65, or during one of the three following months, but your coverage will be delayed by up to three additional months: If you enroll during the third month after you turn 65, you’ll have to wait another three months for your coverage to become effective, meaning you’d have coverage starting six months after you turn 65.

If you’re already receiving Social Security or Railroad Retirement Benefits, you’ll be automatically enrolled in Medicare Part A and Part B on the first day of the month you turn 65, although you’ll have a chance to make changes to how your coverage works prior to turning 65. Most seniors do not pay a premium for Part A, but everyone pays a premium for Part B (except some individuals who are also eligible for Medicaid, and for whom the Medicaid program pays the Part B premiums).

If you’re going to be automatically enrolled, you’ll get information in the mail from Medicare about three months before you turn 65. You’ll be able to decide whether you want to go ahead with the auto-enrollment, skip enrollment, or sign up for Medicare Part C (Medicare Advantage) instead. You’ll also get information about enrolling in Medigap (supplemental insurance) and Medicare Part D (prescription drug coverage).

If you miss your window

If you don’t enroll in Medicare A and/or B during your seven-month open enrollment window, you’ll have a chance to enroll during general open enrollment, which runs from January 1 to March 31 each year.

But there’s a penalty for late enrollment in Medicare Part B, amounting to a 10 percent premium increase for each full 12 month period that you could have been enrolled in Medicare B but weren’t – this penalty continues for as long as you’re enrolled in Medicare, so it’s best to enroll when you’re first eligible. The penalty for late enrollment in Part B does not apply if you had creditable coverage from an employer-sponsored plan (from your own current employer or your spouse’s current employer) during the time that you delayed enrollment in Part B. When that employer-sponsored coverage ends, you’ll have an eight-month window during which you can enroll in Part B, without a penalty.

But if you delay Part B enrollment to save money on premiums, without having coverage from a current employer in place, you’ll likely be subject to the late enrollment penalty when you do enroll during the general enrollment period in a future year.

(There’s a penalty for late enrollment in Medicare A too, but it only applies to people who have to pay a premium for Medicare A, and most seniors receive Medicare A with no premium.)


Louise Norris is an individual health insurance broker who has been writing about health insurance and health reform since 2006. She has written dozens of opinions and educational pieces about the Affordable Care Act for healthinsurance.org. Her state health exchange updates are regularly cited by media who cover health reform and by other health insurance experts.