When You Can Start Medicare Coverage

The Main Ages and Situations That may have access to You

You can enroll in Medicare at age 65, or earlier if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease or ALS. Most people become may be able to access at 65 regardless of work history, but the exact month you can start depends on your birthday and when you sign up.

If you are already getting Social Security retirement benefits when you turn 65, Medicare enrollment happens automatically — you do not need to do anything. If you are not yet taking Social Security, you will need to enroll in Medicare yourself during your enrollment window, which opens three months before the month you turn 65.

Key Takeaways

You become may be able to access for Medicare at age 65, or at any age if you have received SSDI for 24 months, have end-stage renal disease, or have ALS.
Your enrollment window opens three months before the month you turn 65 and stays open for three months after, giving you a seven-month window total.
If you miss your initial enrollment window, you may face a permanent penalty on your premiums, so timing matters even if you do not plan to use Medicare right away.
You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
Part A (hospital insurance) is usually free at 65 if you or your spouse paid Medicare taxes for at least 10 years; Part B (medical insurance) has a monthly premium.

Enrollment Windows and important date

Your Initial Enrollment Period is a seven-month window: it starts three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, you can enroll from March through September. You can enroll in any of those months, and coverage will begin on the first day of your birth month or the month you enroll, whichever is later.

If you miss this window, you enter the General Enrollment Period, which runs January 1 through March 31 each year. Coverage under this later enrollment begins July 1. However, missing your initial window can result in a permanent increase to your Part B premium — typically 10 percent per year you delayed, for as long as you have Medicare. This penalty applies even if you were working and had employer coverage.

There is one exception: if you or your spouse were still working and had health insurance through that job, you may may have access to for a Special Enrollment Period that lets you enroll without penalty up to eight months after your employment or coverage ends. You will need to show proof of that employer coverage when you enroll.

Medicare Before Age 65

You can start Medicare at any age if you have been receiving SSDI for 24 consecutive months. This means you become may be able to access two years after your SSDI benefits begin, not two years after you explore. Medicare enrollment for SSDI recipients happens automatically — you will receive your Medicare card in the mail about a month before your coverage starts.

You also may have access to for Medicare at any age if you have end-stage renal disease (permanent kidney failure requiring dialysis or a transplant) or ALS (amyotrophic lateral sclerosis, also called Lou Gehrig's disease). For end-stage renal disease, you can enroll as soon as you are diagnosed or begin dialysis, and coverage can begin as early as the first day of the month you enroll. For ALS, you become may be able to access the month your diagnosis is confirmed.

How to Enroll When Your Time Comes

You have three ways to enroll: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. The online method is fastest — you can complete enrollment in about 10 minutes if you have your Social Security number and birth date handy.

When you enroll, you will choose between Original Medicare (Part A and Part B) or a Medicare Advantage plan (Part C), which is an alternative way to receive your Part A and Part B benefits through a private insurance company. You will also decide whether to add prescription drug coverage (Part D). If you enroll in Original Medicare, you have until December 31 of the year you turn 65 to add Part D without penalty; if you miss that important date, you pay more per month for as long as you have Medicare.

Have these documents ready when you enroll: your Social Security number, your birth date, your citizenship or immigration status, and information about any current health insurance you have. If you are enrolling by phone or in person, bring your Medicare card once it arrives, or your Social Security card as proof of identity.

Part A and Part B: What Is Automatic and What Costs Extra

Part A covers hospital stays, skilled nursing facility care, hospice, and some home health services. If you or your spouse paid Medicare taxes for at least 10 years, Part A is free — you pay no monthly premium. If you do not meet the 10-year requirement, you can still enroll and pay a monthly premium, which varies based on how many years you or your spouse paid in.

Part B covers doctor visits, outpatient care, medical equipment, and preventive services. Part B has a monthly premium that changes each year; in 2024, the standard premium is $164.90 per month, though higher earners pay more. You pay this premium whether you use Medicare or not. Part B also has an annual deductible (currently $240) that you pay before Medicare starts covering services.

If you are still working at 65 and have health insurance through your job, you may be able to delay Part B enrollment without penalty. Ask your employer's benefits office whether you may have access to for a Special Enrollment Period, because the rules depend on your employer's size and the type of coverage you have.

What Happens If You Miss Your Enrollment Window

If you do not enroll during your Initial Enrollment Period and you do not may have access to for a Special Enrollment Period, you can still enroll during the General Enrollment Period (January 1 through March 31 each year). However, your coverage will not begin until July 1, leaving you without Medicare coverage for several months.

More importantly, you will owe a permanent penalty. Your Part B premium increases by 10 percent for each full 12-month period you were may be able to access but did not enroll. This penalty stays with you for life — even if you switch plans or move to a different state. For example, if you were may be able to access at 65 but did not enroll until age 68, you would pay 30 percent more per month forever.

Part D (prescription drug coverage) has a similar penalty: if you go 63 days or longer without creditable drug coverage, you pay 1 percent more per month for each month you were without coverage. This penalty also lasts as long as you have Medicare.

Frequently Asked Questions

Can I delay Medicare if I am still working at 65?

You can delay Part B if you have health insurance through your current job and your employer has 20 or more employees. You must enroll in Part A, but you can wait on Part B without penalty as long as you enroll within eight months after your employment or coverage ends. Ask your employer's benefits office to confirm you may have access to for this exception before you turn 65.

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

You must be a U.S. citizen or a permanent resident who has lived in the United States for at least five consecutive years to enroll in Medicare. If you are a permanent resident, bring your green card or other immigration documents when you enroll. Undocumented immigrants do not may have access to for Medicare.

Do I have to enroll in Part D when I turn 65?

You do not have to enroll in Part D at 65, but if you go without creditable prescription drug coverage for more than 63 days, you will pay a permanent penalty when you do enroll. If you do not take prescription medications, you can skip Part D, but enroll later if your situation changes.

What if I am on disability but not yet 65?

If you have been receiving SSDI for 24 months, you automatically become may be able to access for Medicare. You do not need to do anything — Medicare will be added to your benefits automatically. Your Medicare card will arrive in the mail about a month before your coverage begins.

Can I change my Medicare plan after I enroll?

Yes, but only during specific windows. You can switch plans during the Annual Enrollment Period (October 15 through December 7 each year), with coverage changes taking effect January 1. If you recently moved, lost employer coverage, or may have access to for a Special Enrollment Period, you may be able to change plans outside this window.

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.