When to Sign Up for Medicare: Your Enrollment Windows Explained

Medicare enrollment happens during specific windows, and missing them usually costs you money for life

You become may be able to access for Medicare at 65, but you do not automatically get it. You have to sign up during one of three enrollment periods, and each one has different rules about when you can join and what you pay. The main window is your Initial Enrollment Period, which runs for seven months centered on the month you turn 65 — three months before, the month itself, and three months after. If you miss that window, you can still sign up during the General Enrollment Period (January 1 to March 31 each year), but you will pay a permanent penalty on your premiums. A third window, Special Enrollment Period, opens if you lose employer coverage or move to a new state, and it does not carry a penalty.

Key Takeaways

Your Initial Enrollment Period is seven months long: three months before you turn 65, the month you turn 65, and three months after — and this is the only window without a lifetime penalty for late sign-up.
If you have health insurance through your job or your spouse's job when you turn 65, you can delay Medicare without penalty as long as the coverage lasts, but you must sign up within eight months of losing that coverage.
Missing your Initial Enrollment Period means paying a 10 percent permanent increase to your Part B premium and a 1 percent permanent increase to your Part D premium for every 12 months you delay.
You can sign up for Medicare through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
If you are still working at 65 and covered by your employer's health plan, tell Medicare about it when you sign up to avoid paying for coverage you do not need yet.

Your Initial Enrollment Period: The seven-month window with no penalty

Your Initial Enrollment Period starts three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your window opens in March and closes in September. During this time, you can sign up for Medicare Part A (hospital insurance) and Part B (medical insurance) without any penalty for waiting.

This is the only enrollment window that does not carry a lifetime cost for signing up late. If you miss it, you will pay more for the rest of your life. That is why it matters to mark your calendar now, even if you are years away from 65.

You do not have to sign up on the first day. You can sign up anytime during those seven months. But if you wait until the last month, you risk missing the important date if mail is slow or if you run into questions that take time to answer.

When you can delay Medicare without penalty

If you are still working at 65 and covered by health insurance through your job or your spouse's job, you do not have to sign up for Medicare right away. You can delay Part B (and Part D, the prescription drug plan) without paying a penalty, as long as your employer coverage lasts. Part A (hospital insurance) is different — you should still sign up for it during your Initial Enrollment Period, because it has no monthly premium and covers hospital stays.

The rule is called creditable coverage. Your employer's plan is creditable if it covers at least as much as Medicare Part B does. Most large employer plans may have access to. Once you lose that coverage — whether you retire, your spouse retires, or your employer ends the plan — you have eight months to sign up for Part B and Part D without paying a penalty. If you wait longer than eight months, the permanent premium increase kicks in.

Tell Medicare about your employer coverage when you sign up. You will need your employer's plan name and the date coverage started. This protects you from being charged for a period when you did not need Medicare.

The General Enrollment Period: Your backup window, with a cost

If you miss your Initial Enrollment Period and you do not have creditable employer coverage, you can sign up during the General Enrollment Period, which runs from January 1 to March 31 every year. Coverage starts July 1 of that year.

The catch is the penalty. You will pay a 10 percent permanent increase to your Part B premium for every 12 months you were may be able to access but did not sign up. If you were may be able to access for three years and did not sign up, you pay 30 percent more for Part B for the rest of your life. The same logic applies to Part D (prescription drug coverage): 1 percent per 12 months of delay.

These penalties do not go away. Even if you sign up years later, you keep paying them. That is why the Initial Enrollment Period matters so much — it is your only chance to avoid this cost.

Special Enrollment Periods: When you can sign up outside the main windows

A Special Enrollment Period opens if certain life changes happen. The most common trigger is losing health insurance through an employer, a spouse's employer, or COBRA (the federal law that lets you keep employer coverage for a limited time after you leave a job). You have two months from the date you lose coverage to sign up for Medicare without penalty.

Other triggers include moving to a new state, losing coverage because your employer went out of business, or being a U.S. citizen living abroad and returning to the United States. If any of these happen, contact Medicare to confirm you may have access to for a Special Enrollment Period. You will need to show proof of the change — a termination letter from your employer, a lease showing your new address, or a passport showing your return date.

Special Enrollment Periods do not carry a penalty, even if you are signing up late. That makes them valuable if you missed your Initial Enrollment Period for a reason that qualifies.

How to sign up during your enrollment window

You have three ways to sign up: online, by phone, or in person. The fastest is usually online at Medicare.gov. You will need your Social Security number, birth date, and citizenship information. The site walks you through the steps and tells you right away if you are may be able to access.

You can also call 1-800-MEDICARE (1-800-633-4227). A representative will ask the same questions and can answer questions about your specific situation. The line is open 24 hours a day, seven days a week. Wait times are usually shorter early in the morning or on weekdays.

If you prefer to sign up in person, visit your local Social Security office. You can find the nearest one at ssa.gov or by calling 1-800-772-1213. Bring your birth certificate, proof of citizenship (passport or naturalization papers), and proof of residence (a recent utility bill or lease).

What happens after you sign up

Once you sign up, Medicare processes your request and sends you a Medicare card in the mail. This usually takes two to four weeks. Your coverage starts on the first day of the month in which you sign up, or the first day of the following month if you sign up after the 15th.

Before your card arrives, write down your Medicare number (it will be on the confirmation notice you get). You will need it to show doctors and hospitals. Once your card arrives, keep it with you when you go to medical appointments.

If you signed up for Part B and Part D, you will also get information about choosing a plan. Part B is automatic once you sign up, but Part D (prescription drug coverage) requires you to pick a plan. If you do not pick one during your enrollment window, you will pay a penalty when you do sign up, similar to the Part B penalty.

Frequently Asked Questions

What if I turn 65 and I am still working full-time?

You can delay Part B and Part D if your employer covers you, but sign up for Part A anyway — it has no premium and covers hospital stays. Once you stop working or lose coverage, you have eight months to sign up for Part B and Part D without penalty. After eight months, you pay a permanent increase to both premiums.

Can I change my mind after I sign up?

Yes, during your Initial Enrollment Period. You can change which parts you sign up for or switch plans. After your Initial Enrollment Period ends, changes are limited to the General Enrollment Period (January 1 to March 31) or a Special Enrollment Period if you may have access to. Outside those windows, you are locked into your choices for the year.

What if I do not know my exact birth date?

Call 1-800-MEDICARE or visit your local Social Security office. They can look up your birth date using your Social Security number. You will need to bring identification to the Social Security office, but you can handle it by phone with Medicare.

Do I have to sign up for Part D when I sign up for Medicare?

No, but if you do not sign up when you are first may be able to access and you go without prescription drug coverage, you will pay a 1 percent penalty for every month you delay. If you do not take prescription drugs now, you can wait, but sign up within 63 days of your first need to avoid the penalty.

What if I am on disability and turn 65?

If you have been receiving Social Security Disability Insurance (SSDI), you automatically switch to regular Social Security retirement benefits at 65, and Medicare Part A is automatic. You still need to sign up for Part B and Part D during your Initial Enrollment Period to avoid penalties. Contact Medicare to confirm your Part A coverage is in place.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.