When You Become Eligible for Medicare by Age

Medicare starts at age 65 for most people

You become may be able to access for Medicare at age 65, regardless of your work history or income. This is the standard age set by federal law. You do not have to retire or stop working to sign up — you only need to reach 65 and be a U.S. citizen or permanent resident who has lived in the country for at least five years.

The month you turn 65, you enter your Initial Enrollment Period, which lasts seven months total: three months before your birthday month, your birthday month itself, and three months after. If you sign up during this window, your coverage can start as early as the first day of your birthday month. If you miss this period, you may face a permanent penalty on your premiums.

You do not automatically receive Medicare when you turn 65. You must sign up through Social Security, Medicare.gov, or by calling 1-800-MEDICARE. Even if you are still working and have employer health insurance, you should understand the rules about when to enroll — the rules differ depending on whether your employer has 20 or more employees.

Key Takeaways

Medicare may be able to access begins at age 65 for U.S. citizens and permanent residents who have lived in the country for at least five years.
Your Initial Enrollment Period lasts seven months: three months before you turn 65, your birthday month, and three months after.
You must actively sign up for Medicare during your enrollment period; it does not happen automatically when you turn 65.
If you delay enrollment past your Initial Enrollment Period without a valid reason, you will pay a higher premium for as long as you have Medicare.

What happens if you are still working at 65

If you are still employed and covered by your employer's health plan, you may be able to delay Medicare enrollment without penalty — but only under specific conditions. The rule depends on the size of your employer. If your company has 20 or more employees, you can usually stay on the employer plan and delay Medicare. If your company has fewer than 20 employees, you must sign up for Medicare when you turn 65, even if you have employer coverage.

When you do leave your job or lose employer coverage, you have an eight-month window to sign up for Medicare without penalty. This is called a Special Enrollment Period. The eight months start the month after your employment or coverage ends. If you wait longer than eight months, you will pay a penalty.

Talk to your employer's benefits office before you turn 65 to find out how many employees work there and what your options are. This conversation can save you from an expensive mistake.

Medicare may be able to access before age 65

Some people become may be able to access for Medicare before 65. You may sign up at any age if you have received Social Security Disability Insurance (SSDI) for 24 months, or if you have End-Stage Renal Disease (ESRD) or Amyotrophic Lateral Sclerosis (ALS). These are the only three paths to Medicare before 65.

If you receive SSDI, Medicare begins automatically 24 months after your disability benefits start. You do not need to sign up separately. If you have ESRD or ALS, you can sign up for Medicare right away — you do not have to wait. Contact Social Security or Medicare.gov to begin the process.

The different parts of Medicare and when they start

Medicare has four parts, and they do not all start on the same date. Part A (hospital insurance) and Part B (medical insurance) can both start on the first day of your birthday month if you sign up during your Initial Enrollment Period. Part D (prescription drug coverage) also starts the first of your birthday month if you enroll on time.

Part C (Medicare Advantage) is a private insurance alternative to Parts A and B. If you choose Part C instead of Original Medicare, it can start on the first day of any month after you sign up, depending on the plan. Some plans have specific start dates, so check with the plan directly.

If you miss your Initial Enrollment Period, your coverage will start the first of the month after you sign up — not retroactively. This is another reason to enroll on time.

Penalties for late enrollment

If you do not sign up for Part B during your Initial Enrollment Period and you do not have a valid reason for the delay, you will pay a late enrollment penalty for as long as you have Medicare. The penalty is 10 percent of the standard Part B premium for each full 12-month period you were may be able to access but not enrolled. If you waited three years to sign up, for example, you would pay 30 percent more than the standard premium.

Part D (prescription drug) has a similar penalty. If you go 63 days or longer without creditable drug coverage, you pay a penalty when you finally enroll. The penalty amount depends on how long you went without coverage.

Part A does not usually have a late enrollment penalty if you have worked long enough to earn Part A coverage. However, if you do not have enough work credits, you may pay a penalty. The rules are complex, so contact Medicare directly if you are unsure.

How to sign up for Medicare

You can sign up for Medicare in three ways: online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. Online is usually the fastest option. You will need your Social Security number, proof of citizenship or permanent residency, and information about any current health coverage you have.

If you are already receiving Social Security benefits when you turn 65, you may be enrolled in Medicare automatically. Check your Social Security statement or contact Social Security to confirm. If you are not yet receiving benefits, you must sign up for Medicare separately — Social Security will not do it for you.

Sign up during your Initial Enrollment Period to avoid delays and penalties. If you miss the window, you can still enroll during the General Enrollment Period (January 1 through March 31 each year), but your coverage will not start until July 1, and you will pay a penalty.

Frequently Asked Questions

Do I have to sign up for Medicare the month I turn 65?

No. Your Initial Enrollment Period is seven months long — three months before your birthday month, your birthday month, and three months after. You can sign up anytime during this window. However, if you want coverage to start on the first day of your birthday month, you should sign up by the end of that month.

What if I am not a U.S. citizen?

You may be may be able to access for Medicare if you are a permanent resident (green card holder) and have lived in the United States for at least five years. Citizenship is not required. Contact Medicare.gov or call 1-800-MEDICARE to confirm your status.

Can I delay Medicare if I have health insurance through my spouse's job?

Yes, if your spouse's employer has 20 or more employees. You can stay on their plan and delay Medicare without penalty. When you leave that coverage, you have eight months to sign up for Medicare without a penalty. If your spouse's employer has fewer than 20 employees, you must sign up for Medicare at 65.

What happens if I sign up late?

If you enroll after your Initial Enrollment Period ends, your coverage will start the first of the month after you sign up, not retroactively. You will also pay a permanent late enrollment penalty on your Part B and Part D premiums for as long as you have Medicare.

Do I need to sign up for all four parts of Medicare?

No. Part A and Part B are Original Medicare. You can choose Part C (Medicare Advantage) instead, which is a private plan that covers hospital and medical care. Part D (prescription drug coverage) is separate and optional, but you should enroll if you take medications, or you may pay a penalty later.

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.