How to Sign Up for Medicare: Your Guide to Enrollment

When you can enroll for health coverage, the best ways to do it and how to avoid penalties

Dena Bunis and Kimberly Lankford,

AARP

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En español

Published December 08, 2022

/ Updated September 09, 2024

AARP (Source: Getty Images)

Key takeaways

You get a seven-month window to sign up for Medicare.
You’ll need to take steps to enroll.
You can delay enrolling if you or your spouse has employer coverage.
Expect to make additional coverage decisions.
Several resources are available to help.

Turning 65 is a milestone for most Americans because they become eligible for Medicare health care coverage.

But you can sign up only at certain times, and you need to make important decisions about other types of coverage, so doing your homework before your birthday is a good idea. If you make Medicare enrollment mistakes, you could end up with lifetime late enrollment penalties and expensive coverage gaps.

Here are the most important things you need to know about when and how to enroll in Medicare.

When can I sign up for Medicare?

Your 65th birthday sets the stage for your initial enrollment period (IEP) when you can enroll in Medicare without fear of a penalty for signing up late. Your IEP lasts seven months: the three months before your birthday month, your birthday month and the three months after.

At this time, you can sign up for Medicare Part A, which covers hospitalization, and Part B, which covers doctors’ services and outpatient care.

You can delay signing up for Medicare at 65 if you or your spouse still works and you have health insurance from that employer. In that case, you will qualify for a special enrollment period (SEP) that lasts up to eight months after you lose employer coverage.

If you neglect to sign up for Medicare Part B during your IEP and don’t qualify for a SEP, you’ll get another chance to sign up during Medicare’s annual general enrollment period Jan. 1 to March 31 each year. Your coverage will begin the first of the month after you enroll, but you’ll likely have to pay a late enrollment penalty for as long as you have Medicare.

Some people younger than 65 qualify for Medicare if they receive disability benefits or have certain conditions, such as end-stage renal disease (ESRD), better known as kidney failure, or amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease.

How do I sign up for Medicare for the first time?

If you receive Social Security or Railroad Retirement Board (RRB) benefits at least four months before your 65th birthday, you’ll be enrolled automatically in Medicare Part A and Part B. Rules are different for residents of Puerto Rico.

You’ll receive your Medicare card in the mail and can start using it the month you turn 65. If your birthday falls on the first day of a month, your coverage will start a month earlier. If you hold off enrolling in Part B, send back the Medicare card and enroll later.

If you’re not getting Social Security or RRB benefits at 65, you can sign up on the Social Security Administration website during your initial enrollment period or a special enrollment period if you delayed enrolling while you had employer coverage. If you miss those deadlines, call Social Security at 800-772-1213, or visit a local office to sign up during a general enrollment period.

Do I have to sign up for Medicare at 65 if I have insurance?

You may not have to enroll in Medicare at age 65 if you or your spouse is still working and has comprehensive health insurance through that employer. The rules depend on the size of the employer:

Help to enroll in Medicare

The Social Security Administration (SSA), which handles Medicare enrollment, recommends signing up online for Medicare. If you need additional assistance to sign up, you can meet with a representative at a local SSA office.

You also can get enrollment help through your State Health Insurance Assistance Program (SHIP) and other resources.

If the company has 20 or more employees, the employer coverage is primary and Medicare is secondary. The employer can’t require you to sign up for Medicare at 65.

You’ll qualify for an SEP to sign up for Medicare without penalty while you have the employer coverage and for up to eight months after that job-based coverage ends.

Even though you aren’t required to enroll in Medicare at 65, many people sign up for Part A during their IEP because you typically don’t pay premiums for Part A. You can delay signing up for both Part A and Part B if you want to make tax-advantaged contributions to a health savings account (HSA).

If the employer has fewer than 20 workers, it may require that you enroll in Medicare Parts A and B. Your work insurance often becomes secondary and fills gaps in Medicare coverage.

You’ll also have to sign up for Medicare at 65 if you have:

The Affordable Care Act’s (ACA) health insurance marketplace. When you turn 65 with ACA, you must transition from an ACA plan to Medicare.
Consolidated Omnibus Budget Reconciliation Act (COBRA) coverage. If you lost your job and signed up for COBRA to extend employer insurance, this doesn’t protect you against late penalties for not signing up for Medicare.
Retiree health insurance. You typically need to enroll in Medicare at 65 for these programs to help fill in the gaps. (Special rules apply for federal retirees.)
Tricare military health insurance. You must enroll in Medicare Parts A and B when you’re eligible. Then Tricare for Life fills in the gaps for some services Medicare doesn’t cover.

Do I need other coverage?

Enrolling in Medicare Parts A and B is the first step, but you’ll need to make other decisions.

Original Medicare or Medicare Advantage? Do you want coverage from original Medicare, the federal program that allows you to use any doctor who accepts Medicare, or a private Medicare Advantage (Part C) plan, which has limited provider networks but usually includes prescription drug coverage? Most Advantage plans offer some dental, hearing and vision benefits.

Original Medicare decisions. If you choose original Medicare, you may need to get a separate Part D prescription policy unless you have comparable drug coverage from an employer, former employer, Tricare or other source.

You may want a Medicare supplement policy, also known as Medigap, to help pay Medicare’s deductibles and copayments. Private insurers sell both types of policies.

Look at the steps to choose and enroll in a Part D prescription drug plan and Medigap policy before your 65th birthday.

Medicare Advantage decisions. If you choose this all-in-one private coverage, you won’t need extra policies. You’ll have several plans to choose from in your area with different coverage, costs and provider networks.

Here, too, learn the steps to choose and enroll in a Medicare Advantage plan ahead of time.

You can sign up for a Part D or Medicare Advantage plan only at certain times after you enroll in Medicare. You can switch plans every year during open enrollment Oct. 15 to Dec. 7 for new coverage starting Jan. 1.

You can buy a Medigap policy at any time, but insurers in most states can reject you or charge more because of preexisting conditions if you buy a policy more than six months after enrolling in Medicare Part B.

This article, originally published in 2020, has been updated with new information for 2024.

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Dena Bunis covered Medicare, health care, health policy and Congress. She also wrote the “Medicare Made Easy” column for the AARP Bulletin. An award-winning journalist, Bunis spent decades working for metropolitan daily newspapers, including as Washington bureau chief for the Orange County Register and as a health policy and workplace writer for Newsday.

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.