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I didn’t enroll in Medicare when I turned 65. Can I sign up later?

Kimberly Lankford,

Updated January 24, 2024

AARP

En español

Published February 10, 2023

/ Updated January 24, 2024

Yes, but you can enroll only at certain times. You may also have to pay a late enrollment penalty unless you qualify for what’s considered a special enrollment period (SEP).

While you’re eligible for Medicare at age 65, you’re automatically enrolled if you began receiving Social Security or Railroad Retirement Board benefits at least four months before your 65th birthday. Otherwise, you need to take steps to sign up yourself.

When is the earliest I can enroll in Medicare?

Unless you qualify for Medicare before age 65 because of a disability, the first time you’re eligible to sign up is during your initial enrollment period (IEP), which begins on the first day of the month three months before the month you turn 65 and lasts for three months after your birthday month.

That means even if you’re a few months past your 65th birthday, you still may be in your initial enrollment period. Where you are in your IEP determines when your Medicare coverage starts:

If you enroll during those first three full months before your birthday, your coverage begins on the first day of the month you turn 65 or the first day of the previous month if your birthday is on the first of the month.

If you sign up during the month you turn 65 or the three months after your birthday month, coverage begins on the first day of the following month.

What if I’m past my initial enrollment period?

The enrollment rules are different for Medicare Part A, which provides coverage for hospitalization, than for Medicare Part B coverage, which helps pay for doctor and outpatient services.

If you qualify for premium-free Part A, like most people, you can sign up for that coverage during your initial enrollment period or any time after without a penalty. Your Part A coverage is retroactive for up to six months but no earlier than the month you turned 65.

Part B isn’t as flexible. If you missed your initial enrollment period, you may be able to sign up later without penalty if you qualify for a special enrollment period.

You can qualify for a special enrollment period if you or your spouse is still working and you have health insurance from that employer. In that case, you have a SEP to sign up for Medicare any time while you have that coverage and for up to eight months after the employment or coverage ends, whichever occurs first.

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Only coverage from a current employer counts. You won’t qualify for a SEP if you have coverage from your former employer’s plan through COBRA, the federal Department of Veterans Affairs, military retiree health coverage from Tricare, a labor union retiree plan or any other retiree health plans. You or your spouse must be actively working for the company providing the insurance.

If you sign up while still working or during the first month after you leave the plan, Part B coverage will begin on the first day of the month after you enroll or the first day of any of the following three months.

If you sign up during the remaining seven months after you or your spouse stops working, your coverage begins on the first day of the following month. For example, if you stop working in April but you sign up for Part B in June, your coverage begins in July.

The SEP terms expanded in 2023 to include other circumstances, like missing an initial enrollment period because of a natural disaster.

Premium-free Part A coverage begins six months retroactively, but no earlier than the month you turn 65.

What if I don’t qualify for a special enrollment period?

People who qualify for premium-free Part A can sign up at any time after they’re eligible without penalty.

But you can only sign up for Part B during Medicare’s general enrollment period (GEP) — from Jan. 1 to March 31 each year — if you miss your initial enrollment period and don’t qualify for a special enrollment period. Your coverage will take effect the beginning of the following month, and you may have to pay a Part B late enrollment penalty.

The GEP also applies if you have to pay Part A premiums because you or your spouse haven’t paid enough quarters of Medicare taxes .

Keep in mind

Part D. The enrollment and penalty rules are different for Part D prescription drug coverage.

If you missed your initial enrollment period and have other prescription coverage considered at least as good as Part D, called “creditable coverage,” you can usually delay signing up for Part D. You usually have to buy a Part D plan within two months after losing creditable coverage or else you may have to pay a Part D late enrollment penalty. You won’t be subject to a late enrollment penalty, however, if you qualify for Extra Help, the federal program that helps people with low incomes and assets pay Part D premiums and out-of-pocket costs.

Medigap. If you’re 65 or older, you can get any Medigap policy available in your area for the six months starting on the first of the month that you have Medicare Part B. During that time insurers can’t deny you coverage or charge you more for a preexisting condition.

You can apply for coverage at any time. But after six months, Medigap insurers in most states can reject you or charge more because of your health.

Medicare Advantage. To enroll in Part C, better known as an all-in-one Medicare Advantage plan, you must first have Part A and Part B coverage. You can sign up during your initial enrollment period for Medicare. After that, if you’ve missed your initial enrollment period, you can sign up during Medicare’s annual open enrollment period from Oct. 15 to Dec. 7 each year. Coverage starts on Jan 1. You may also be eligible to enroll in Medicare Advantage during other times, such as when switching into a plan that receives a five-star quality rating if one is available in your area.

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Kimberly Lankford is a contributing writer who covers Medicare and personal finance. She wrote about insurance, Medicare, retirement and taxes for more than 20 years at Kiplinger’s Personal Finance and has written for The Washington Post and Boston Globe. She received the personal finance Best in Business award from the Society of American Business Editors and Writers and the New York State Society of CPAs’ excellence in financial journalism award for her guide to Medicare.