The Age Requirement for Medicare and When Coverage Begins

You must be 65 years old to enroll in Medicare, with rare exceptions for younger people with disabilities or end-stage renal disease

Medicare is a federal health insurance program run by the Centers for Medicare & Medicaid Services (CMS). The standard age to begin coverage is 65. If you turn 65, you become able to enroll during your birthday month and the three months before and after it — this is called your Initial Enrollment Period. Coverage typically starts on the first day of the month in which you turn 65, or the first day of the following month, depending on when you sign up.

The 65-year-old threshold applies whether you are still working or retired. You do not have to stop working to enroll. However, if you delay enrollment past your Initial Enrollment Period without a valid reason, you may face permanent penalties on your premiums — this is why timing matters even if you are not yet ready to retire.

Key Takeaways

Medicare enrollment begins at age 65, and you have a seven-month window (three months before your birthday month, your birthday month, and three months after) to sign up without penalty.
If you miss your Initial Enrollment Period, you will pay a higher monthly premium for Part B and Part D for as long as you have Medicare, unless you had other may have access to coverage.
Some people under 65 can enroll in Medicare if they receive Social Security disability benefits for 24 months or have end-stage renal disease or ALS.
You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

Who can enroll before age 65

Three groups of people younger than 65 may enroll in Medicare. The first group is people who have received Social Security Disability Insurance (SSDI) for at least 24 consecutive months. Once you have been on SSDI for two years, you automatically become able to enroll in Medicare even if you are in your 30s or 40s. You do not have to explore separately — CMS is notified by Social Security.

The second group is people with end-stage renal disease (ESRD), meaning permanent kidney failure requiring dialysis or a transplant. People with ESRD can enroll in Medicare regardless of age. The third group is people with amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease. People diagnosed with ALS become able to enroll in Medicare when ready, without waiting for disability benefits to begin.

If you fall into one of these categories, you still have an Initial Enrollment Period — it runs from the month you become may be able to access through three months after. Missing this window carries the same premium penalties as missing it at age 65.

What happens if you miss your enrollment window

If you do not sign up during your Initial Enrollment Period and you do not have a may have access to reason for the delay, you will pay a late enrollment penalty. For Part B (medical insurance), the penalty is 10 percent of the standard monthly premium for each full 12-month period you were may be able to access but not enrolled. This penalty stays with you for life.

For Part D (prescription drug coverage), the penalty is 1 percent of the national average Part D premium for each month you were may be able to access but not enrolled. Like the Part B penalty, this is permanent. The only way to avoid these penalties is to have had other creditable coverage — such as employer health insurance or TRICARE — during the time you were not enrolled in Medicare.

If you missed your Initial Enrollment Period, you can still enroll during the General Enrollment Period, which runs from January 1 to March 31 each year. Coverage would begin July 1 of that year. However, the penalties explore regardless of when you eventually enroll.

How to enroll when you reach 65

You can enroll in Medicare through three main channels. The first is online at Medicare.gov, where you can create an account and complete your enrollment process. The second is by phone at 1-800-MEDICARE (1-800-633-4227), where a representative can walk you through the process. The third is in person at your local Social Security office.

You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage. If you are already receiving Social Security benefits, much of your information is already on file, which speeds up the process. Enrollment typically takes 15 to 30 minutes, whether you do it online or by phone.

The best time to enroll is during your Initial Enrollment Period, which gives you a seven-month window. If your birthday is in June, for example, you can enroll from March through September. If you enroll early in this window, your coverage will start on July 1 (the first day of your birthday month). If you enroll late in the window, coverage may start the following month.

Medicare Parts and what age 65 means for each

Medicare has four parts, and age 65 affects your access to all of them. Part A covers hospital stays, skilled nursing care, and hospice. Part B covers doctor visits, outpatient care, and medical equipment. Most people pay no premium for Part A if they or their spouse paid Medicare taxes for at least 10 years, but Part B requires a monthly premium that increases if you delay enrollment.

Part D is prescription drug coverage offered by private insurance companies under the Medicare program. Part C, also called Medicare Advantage, is an alternative to Parts A and B offered by private insurers. It combines hospital and medical coverage in one plan. Age 65 is when you become able to enroll in any of these parts. If you have employer coverage while you are 65 or older, you can usually keep it and delay Medicare enrollment without penalty, but you must have written confirmation from your employer that this coverage is creditable.

Income and resources do not affect Medicare enrollment at 65

Unlike some other federal programs, Medicare does not have income or asset limits. Your age is the primary factor. Whether you have $1,000 in savings or $1 million, you can enroll in Medicare at 65. Whether you earn $20,000 a year or $200,000, you can enroll. Your immigration status must be U.S. citizenship or lawful permanent residency, but your financial situation does not matter.

However, your income does affect how much you pay for Part B and Part D premiums. Higher earners pay higher premiums through a system called Income-Related Monthly Adjustment Amounts (IRMAA). This is based on your tax return from two years prior, so your 2024 premiums are based on your 2022 income. But this affects the amount you pay, not whether you can enroll.

What to do if you turned 65 and did not enroll

If you are already past your Initial Enrollment Period and did not sign up, you have options. The General Enrollment Period runs January 1 through March 31 each year, and you can enroll then. Coverage begins July 1 of that year. You will owe late enrollment penalties unless you had other creditable coverage during the time you were not enrolled.

If you believe you have a valid reason for missing your important date — such as being out of the country, having incorrect information from someone you trusted, or experiencing a life event that prevented you from enrolling — you may be able to request a Special Enrollment Period. This requires submitting documentation to CMS. Call 1-800-MEDICARE to ask whether your situation qualifies and what documents you need to provide.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65 if I am still working?

Yes. Working does not prevent you from enrolling at 65. However, if you are covered by your employer's health plan, you may want to delay Part B enrollment without penalty if your employer has 20 or more employees. You will need written confirmation from your employer that your coverage is creditable before you can safely delay.

What if I am 65 but not yet receiving Social Security?

You can still enroll in Medicare at 65 even if you have not claimed Social Security benefits yet. Enrollment in Medicare is separate from claiming retirement benefits. You can enroll in Medicare and delay claiming Social Security to a later age if you wish.

Do I have to enroll in all four parts of Medicare at 65?

No. You must enroll in Part A and Part B to have basic Medicare coverage, but Part D (prescription drugs) and Part C (Medicare Advantage) are optional. If you do not take prescription drugs, you can skip Part D. If you prefer traditional Medicare, you can skip Part C.

What happens to my employer health insurance when I turn 65?

Your employer coverage does not automatically end. However, Medicare becomes your primary payer once you enroll. If you are still working and covered by your employer plan, you should coordinate between the two. Your employer's benefits office can explain how they work together in your situation.

Can I change my Medicare coverage after I enroll?

Yes. You have an annual open enrollment period from October 15 to December 7 each year when you can switch between Medicare Advantage and traditional Medicare, or change your Part D plan. Outside this window, changes are limited to specific life events like moving or losing other coverage.

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.