When and how to sign up for Medicare

You become may be able to access for Medicare the month you turn 65, regardless of whether you are still working. You do not have to wait until you retire. You can sign up starting three months before your 65th birthday and continuing for three months after — this is called your Initial Enrollment Period. If you miss this window, you can still sign up later, but you may pay a permanent penalty on your premiums.

The easiest way to sign up is online at Medicare.gov, where you can create an account and complete the enrollment in about 15 minutes. You can also call 1-800-MEDICARE (1-800-633-4227) and speak to someone who will walk you through it, or visit your local Social Security office in person. If you are already receiving Social Security benefits, you will be enrolled automatically in Medicare Part A and Part B the month you turn 65 — you do not need to do anything, though you should still review what you are getting.

Have your Social Security number, birth date, and citizenship or immigration status ready before you start. If you are still working and have health insurance through your job, tell Medicare that when you sign up — it may change what you pay now and what you owe later.

Key Takeaways

  • You can sign up for Medicare starting three months before you turn 65 and up to three months after, with no penalty during this window.
  • If you are already getting Social Security, Medicare will enroll you automatically, but you should confirm your coverage is correct.
  • You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at a Social Security office.
  • Missing your Initial Enrollment Period means you will pay higher premiums for as long as you have Medicare, so sign up on time even if you do not plan to use it right away.
  • If you are still working and have employer health insurance, tell Medicare during enrollment so your coverage coordinates correctly.

What happens if you miss the enrollment important date

If you do not sign up during your Initial Enrollment Period, you enter a General Enrollment Period that runs from January 1 to March 31 each year. You can sign up then, but coverage does not start until July 1 of that year. More importantly, you will pay a late enrollment penalty — an extra amount added to your Part B premium every month for as long as you have Medicare.

The penalty is 10 percent of the standard Part B premium for each full 12 months you were may be able to access but not enrolled. If you were may be able to access at 65 and did not sign up until age 68, that is three years of penalties, and you will pay them for life. The only exceptions are if you had other health insurance (like coverage through an employer) that was considered "creditable" — meaning it covered at least as much as Medicare Part B — or if you may have access to for a Special Enrollment Period because of a specific life event like losing your job.

The same late penalty applies to Part D (prescription drug coverage). If you go 63 days or more without drug coverage that is at least as good as Medicare's, you will pay an extra amount on your Part D premium forever.

Choosing between Original Medicare and Medicare Advantage

When you sign up, you will choose between two ways to get your Medicare coverage: Original Medicare (Parts A and B) or a Medicare Advantage plan (Part C). This choice shapes what doctors you can see, what you pay out of pocket, and what extra coverage you get.

Original Medicare is run by the federal government. It covers hospital care (Part A) and doctor visits and outpatient care (Part B). You can see any doctor or hospital that accepts Medicare anywhere in the country. You pay a monthly premium for Part B, a deductible when you use services, and coinsurance (a percentage of the cost). You are responsible for anything Medicare does not cover, so many people buy a Medigap policy (supplemental insurance) to fill the gaps. You also need to choose a separate Part D plan for prescription drugs.

Medicare Advantage plans are run by private insurance companies under contract with Medicare. They bundle Parts A, B, and usually D together. Most have lower or zero monthly premiums than Original Medicare, but they typically limit you to a network of doctors and hospitals, require referrals to see specialists, and have higher out-of-pocket costs when you do use care. You cannot use a Medigap policy with a Medicare Advantage plan.

You have until December 7 each year to switch between Original Medicare and Medicare Advantage, or to change which Advantage plan you are in. This is called the Annual Enrollment Period. Changes take effect January 1.

Adding prescription drug coverage and supplemental insurance

If you choose Original Medicare, you must decide whether to buy Part D (prescription drug coverage). You do this at the same time you sign up for Parts A and B, or during the Annual Enrollment Period. Part D is sold by private insurance companies, and the plans vary in which drugs they cover and how much you pay. You can compare plans side by side on Medicare.gov.

You should also consider a Medigap policy if you choose Original Medicare. Medigap covers some of the costs that Original Medicare does not — like deductibles, coinsurance, and copays. There are ten standardized Medigap plans (labeled A through N), and they are sold by private insurers. The same plan letter covers the same benefits no matter which company sells it, but the price varies. You have the best rates if you buy Medigap within six months of turning 65 and enrolling in Part B — after that, insurers can charge you more based on your health history.

If you choose a Medicare Advantage plan, prescription drug coverage is usually included, so you do not buy Part D separately. You cannot buy Medigap to go with Advantage.

What documents you need to have ready

Before you start the enrollment process, gather these documents so you do not have to stop and search for them:

  • Your Social Security number
  • Your birth date and citizenship or immigration status (green card number if applicable)
  • Information about any current health insurance (employer coverage, COBRA, individual policy, or Veterans benefits)
  • A list of your doctors and hospitals, if you want to check whether they are in a Medicare Advantage network
  • A list of your regular medications, if you want to check Part D formularies (the list of drugs each plan covers)

If you are signing up by phone or in person, the person helping you will ask for this information. If you are signing up online, you will enter it into the form. Having it ready means the process takes less time and you are less likely to make a mistake.

Signing up if you are still working or have other coverage

If you are still working and your employer offers health insurance, you do not have to sign up for Medicare at 65 — you can delay without penalty as long as your employer has 20 or more employees. This is called creditable coverage. You should still sign up for Part A (hospital insurance) because it has no premium and covers hospital stays, but you can wait on Part B until you actually retire or lose your job.

When you do retire or lose that coverage, you have eight months to sign up for Part B without paying a late penalty. Tell Medicare at the time of enrollment that you had creditable employer coverage — you will need to provide proof, such as a letter from your employer or a copy of your insurance card.

If you have COBRA (continuation coverage from a former employer), Veterans benefits, or coverage through a spouse's employer, the same rule applies: as long as it is creditable, you can delay Part B without penalty. The key is to sign up within eight months of losing that coverage.

After you enroll: what comes next

Once you complete enrollment, Medicare will mail you a Medicare card within two weeks. This card shows your Medicare number and which parts of Medicare you have. Keep it in a safe place and bring it to every doctor visit.

If you enrolled in Original Medicare, your Part B coverage starts the first day of the month you turn 65 (or the month you enrolled, if that is later). Part A starts the same day. If you chose a Medicare Advantage plan, your coverage starts January 1 of the following year if you enrolled during the Initial Enrollment Period, or on the first of the month after you enroll if you sign up during the Annual Enrollment Period.

Review your coverage as soon as you receive your card. Make sure the information is correct — your name, date of birth, and which parts you have. If something is wrong, call 1-800-MEDICARE right away to fix it. If you enrolled in a Medicare Advantage plan, your insurance company will send you a welcome packet with information about your network doctors, how to get referrals, and how to file claims.

Frequently Asked Questions

Do I have to sign up for Medicare at 65 if I am still working?

You must sign up for Part A (hospital insurance) at 65 even if you are working, because it has no premium and you will need it eventually. You can delay Part B if your employer has 20 or more employees and offers health insurance — but sign up within eight months of retiring or losing that coverage to avoid a permanent penalty.

What if I turn 65 in the middle of the month?

Your Initial Enrollment Period starts three months before the month you turn 65, not three months before the specific date. So if you turn 65 on any day in June, your enrollment period begins in March. Your coverage will start on June 1 if you enroll by March 31, or on the first of the month after you enroll if you sign up later.

Can I change my mind after I enroll?

Yes. If you enrolled in Original Medicare and want to switch to a Medicare Advantage plan (or vice versa), you can do so during the Annual Enrollment Period from October 15 to December 7 each year, with the change taking effect January 1. If you just enrolled and are still in your Initial Enrollment Period, you can also make changes during that time.

What if I do not know which plan to choose?

Medicare.gov has a tool called the Plan Finder where you enter your doctors and medications and it shows you which plans cover them and what you will pay. You can also call 1-800-MEDICARE and ask to speak with a counselor, or contact your State Health Insurance information Program (SHIP) — a free service that helps seniors understand their options. Find your local SHIP at shiptacenter.org.

Do I need to do anything if I am already getting Social Security?

No — you will be enrolled automatically in Parts A and B the month you turn 65. But check the information on your Medicare card when it arrives to make sure it is correct. You still need to choose a Part D plan for prescriptions and decide whether you want a Medigap policy if you are keeping Original Medicare.