When to Sign Up for Medicare: Age Requirements and Enrollment Windows

You become may be able to access for Medicare at 65, but the exact month you can enroll depends on your birthday

Medicare enrollment opens three months before the month you turn 65 and closes three months after. If you turn 65 in June, for example, you can enroll starting in March and must enroll by September to avoid penalties. The Social Security Administration handles enrollment automatically for people already receiving Social Security benefits — they are added to Medicare in the month they turn 65 without having to do anything. Everyone else must enroll themselves through Medicare.gov, by phone, or in person at a Social Security office.

Age 65 is the standard may be able to access age set by federal law. Some people become may be able to access earlier: those on Social Security Disability Insurance (SSDI) for 24 months, those with end-stage renal disease, and those with ALS (amyotrophic lateral sclerosis) can enroll at any age. If you fall into one of these categories, Medicare will contact you about enrollment automatically.

Key Takeaways

You become may be able to access for Medicare at 65, and your enrollment window opens three months before and closes three months after the month you turn 65.
If you already receive Social Security benefits, you are enrolled in Medicare automatically in the month you turn 65 with no action required.
If you do not receive Social Security, you must enroll yourself through Medicare.gov, by calling 1-800-MEDICARE, or at a local Social Security office.
Missing your enrollment window can result in permanent premium penalties unless you have other health coverage that qualifies as creditable coverage.
Some people under 65 become may be able to access if they receive SSDI for 24 months, have end-stage renal disease, or have ALS.

How the enrollment window works and when to act

Your Initial Enrollment Period (IEP) is seven months long: three months before the month you turn 65, the month you turn 65, and three months after. During this window, you can enroll in Medicare Part A (hospital insurance) and Part B (medical insurance) without waiting periods or penalties.

If you miss this window, you enter a different system. You can still enroll, but you may face a late enrollment penalty — an extra charge added to your Part B premium for as long as you have Medicare. The penalty is 10 percent of the standard Part B premium for each full year you were may be able to access but not enrolled. If you were may be able to access at 65 but did not enroll until age 68, you would pay the penalty for the rest of your life.

The one exception is creditable coverage. If you or your spouse are still working and covered by an employer health plan, you may not face a penalty for enrolling late. You will need to show proof that your employer coverage was creditable — your employer's benefits office can provide a letter stating this. Once you or your spouse stops working, you have eight months to enroll in Medicare without penalty.

What happens if you already receive Social Security

If you are already collecting Social Security retirement, spousal, or survivor benefits when you turn 65, the Social Security Administration automatically enrolls you in Medicare Part A and Part B. You do not need to do anything. Your Medicare card will arrive in the mail about two weeks before your 65th birthday.

You can decline Part B if you have other coverage, but you must do this actively — contact Social Security or Medicare to say you do not want it. Part A (hospital insurance) is automatic and free for most people, so declining it is rare.

What to do if you do not receive Social Security

If you are not yet collecting Social Security when you turn 65, you must enroll in Medicare yourself. You have three ways to do this: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office.

Online enrollment through Medicare.gov is usually the fastest. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage. The process takes about 10 minutes. By phone, a representative will walk you through the same questions and can answer questions about your specific situation. In-person enrollment at a Social Security office takes longer but may be helpful if you need to bring documents or have complex circumstances.

You should enroll as early in your window as possible — ideally in the first month it opens. Medicare coverage typically begins the first day of the month after you enroll, though if you enroll in the month you turn 65, coverage can start that same month.

Early enrollment for people under 65

Three groups of people under 65 become may be able to access for Medicare. The largest group is people receiving Social Security Disability Insurance (SSDI) for 24 consecutive months. After 24 months on SSDI, you are automatically enrolled in Medicare Part A at no cost. You can choose to enroll in Part B, which has a monthly premium.

People with end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or transplant — can enroll in Medicare when ready, regardless of age. People with ALS (Lou Gehrig's disease) can also enroll when ready. If you have one of these conditions, contact Medicare or your doctor's office to begin the enrollment process.

Understanding Part A and Part B enrollment

Medicare has two main parts, and your enrollment window covers both. Part A is hospital insurance, covering inpatient hospital stays, skilled nursing facility care, hospice, and some home health services. Most people pay nothing for Part A because they or their spouse paid Medicare taxes while working.

Part B is medical insurance, covering doctor visits, outpatient care, medical equipment, and preventive services. Part B has a monthly premium that changes each year — in 2024 it is $164.90 for most people, though higher earners pay more. If you enroll late in Part B, your premium increases by 10 percent for each year you were may be able to access but not enrolled.

You can enroll in Part A without Part B if you have other coverage, but Part B enrollment is separate. If you decline Part B during your Initial Enrollment Period, you can enroll later during the General Enrollment Period (January 1 to March 31 each year), but you will face a late penalty unless you had creditable coverage.

What to bring and how long enrollment takes

To enroll, have your Social Security number, proof of citizenship or legal residency (passport, birth certificate, or naturalization papers), and information about any current health coverage ready. If you are enrolling by mail, you will need to complete Form CMS-40B and mail it to your local Social Security office — the Medicare website lists the address for your area.

Online enrollment is processed within days. Phone enrollment is completed the same day. In-person enrollment at a Social Security office may take a few weeks to process. Your Medicare coverage typically begins the first of the month after you enroll, though if you enroll between the 1st and 15th of the month you turn 65, coverage can start that same month.

Frequently Asked Questions

What happens if I turn 65 but am still working?

You can still enroll in Medicare at 65. If your employer provides health coverage, you may not need to enroll in Part B right away — you have eight months after you or your spouse stops working to enroll without penalty, as long as your employer coverage is creditable. Contact your employer's benefits office to confirm your coverage qualifies.

Can I delay Medicare enrollment past 65?

Yes, but you will face a late enrollment penalty in Part B unless you have creditable coverage from an employer plan. The penalty is 10 percent of the standard Part B premium for each year you were may be able to access but not enrolled, and it lasts for life. Part A has no penalty if you enroll within eight months of losing employer coverage.

Do I have to enroll in Part B if I do not want it?

You can decline Part B during your Initial Enrollment Period if you have other coverage. You must tell Medicare or Social Security that you do not want it — straightforward not enrolling does not count as declining. If you change your mind later, you can enroll during the General Enrollment Period (January 1 to March 31), but you will pay a late penalty unless you had creditable coverage.

What if I miss my enrollment window?

You can still enroll in Medicare after your Initial Enrollment Period ends, but you will likely face a late penalty in Part B. The exception is if you had creditable coverage from an employer plan — in that case, you have eight months after coverage ends to enroll without penalty. Contact Medicare at 1-800-MEDICARE to discuss your situation.

Will Medicare contact me automatically when I turn 65?

Only if you already receive Social Security benefits. If you do not receive Social Security, Medicare will not contact you — you must enroll yourself. Set a reminder three months before your 65th birthday to begin the enrollment process.

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.