Medicare begins at age 65 for most people, but the exact timing depends on when you sign up

You become may be able to access for Medicare on the first day of the month you turn 65. However, coverage does not start automatically — you have to take action during your enrollment window, or you may face delays and penalties. If you wait past your window, Medicare can start as late as the following year, even if you are already 65.

The enrollment window is seven months long: it starts three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your window runs from March through September. You can sign up during any of those seven months, and your coverage will begin on the first day of the month you turn 65 — as long as you sign up before that month ends.

If you miss your window entirely, you can still sign up later, but your coverage will not start until the following January 1st at the earliest. You will also owe a late enrollment penalty that increases your monthly premium permanently. The penalty is 10 percent of the standard Part B premium for each full year you were may be able to access but not signed up.

Key Takeaways

  • You are may be able to access for Medicare on the first day of the month you turn 65, but you must sign up during your seven-month enrollment window to avoid delays.
  • Your enrollment window opens three months before you turn 65 and closes three months after, giving you a total of seven months to act.
  • If you sign up during your window, coverage starts on the first day of the month you turn 65, regardless of which month within the window you sign up.
  • Missing your enrollment window means coverage does not start until January 1st of the following year, and you will pay a permanent penalty on your Part B premium.
  • Some people under 65 — those on Social Security Disability Insurance or with end-stage renal disease — become may be able to access for Medicare earlier.

Who becomes may be able to access before age 65

Three groups of people can get Medicare before turning 65. The largest group is people who have been receiving Social Security Disability Insurance (SSDI) for at least 24 months. Once you have been on SSDI for two years, you automatically become may be able to access for Medicare at any age.

The second group is people with end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or a transplant. You become may be able to access for Medicare the month your ESRD treatment begins, regardless of age. You will need documentation from your nephrologist or dialysis center showing the start date of treatment.

The third group is people with amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease. You become may be able to access for Medicare the month you are approved for SSDI, without waiting the usual 24 months. You do not have to wait for the two-year SSDI waiting period that applies to other disabilities.

How to sign up during your enrollment window

You can sign up for Medicare through three routes: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. Online is fastest — you can complete the process in about 15 minutes if you have your Social Security number and birth date ready.

When you sign up, you will choose which parts of Medicare you want. Part A (hospital insurance) and Part B (medical insurance) are the main components. Most people sign up for both. If you are still working and have health insurance through your employer, you may be able to delay Part B without penalty — but you must tell Medicare this when you sign up, or you will owe a late penalty later.

If you are already receiving Social Security benefits when you turn 65, Medicare will be offered to you automatically in the mail about three months before your 65th birthday. You can accept it by returning the form, or you can decline it if you have other coverage. If you are not yet receiving Social Security, you must contact Medicare yourself during your enrollment window.

What happens if you miss your enrollment window

If you do not sign up during your seven-month window and you do not have other may have access to coverage, your Medicare coverage will not start until January 1st of the following year. This means if you turn 65 in March and miss the September important date, you will have no Medicare coverage from April through December — a gap of nine months.

During that gap, you are responsible for all medical costs out of pocket unless you have other insurance. You cannot retroactively enroll in Medicare to cover bills from those months. Additionally, you will owe a Part B late enrollment penalty equal to 10 percent of the standard monthly premium for each 12-month period you were may be able to access but not enrolled. If you were may be able to access for three years before signing up, your penalty is 30 percent, and it stays on your premium for life.

There is one exception: if you had creditable coverage — health insurance through an employer, a spouse's employer, or a union — you may not owe a penalty. Creditable coverage means continuous health insurance that is at least as good as Medicare Part B. You will need to provide proof of this coverage when you sign up late, so keep documentation of any employer or group health plan you had while you were 65 or older.

Coordinating Medicare with employer health insurance

If you are still working at age 65 and your employer offers health insurance, you may not need to sign up for Medicare Part B right away. If your employer has 20 or more employees, your employer coverage is considered primary, meaning it pays first, and Medicare pays second. In this situation, you can delay Part B without penalty.

However, you must still sign up for Part A during your enrollment window, even if you are working. Part A has no monthly premium if you or your spouse paid Medicare taxes for at least 10 years, so there is no financial reason to delay it. Signing up for Part A does not affect your employer coverage.

When you leave your job or lose your employer coverage, you have eight months to sign up for Part B without penalty. This is called a Special Enrollment Period. You will need to provide proof that you had employer coverage — usually a letter from your employer's benefits department stating the coverage dates and that it was group health insurance.

State-specific enrollment resources

While Medicare is federal, some states offer additional programs that coordinate with Medicare enrollment. State Health Insurance information Programs (SHIP) provide free counseling about Medicare enrollment, coverage options, and costs. You can find your state's SHIP by calling 1-800-MEDICARE or visiting Medicare.gov.

Some states also run Medicaid programs that work alongside Medicare for people with low income. If you think you may be may be able to access for both Medicare and Medicaid, your state's Medicaid office can explain how the two programs work together and whether you need to take separate steps to enroll in Medicaid.

Your local Area Agency on Aging can also connect you with enrollment help. You can find the agency nearest you by calling the Eldercare Locator at 1-800-677-1116 or visiting eldercare.acl.gov.

Frequently Asked Questions

Can I sign up for Medicare before my 65th birthday?

Yes. Your enrollment window opens three months before the month you turn 65. If you turn 65 in June, you can sign up starting in March. Signing up early does not start your coverage early — it still begins on June 1st — but it ensures you do not miss your window.

What if I turn 65 in the middle of a month?

Your Medicare coverage starts on the first day of the month you turn 65, regardless of the date within that month. If you turn 65 on June 15th, your coverage begins June 1st. You should sign up during your enrollment window so coverage is in place by that date.

Do I have to sign up for Part D (prescription drug coverage) at the same time?

No, but you should sign up for Part D during your initial enrollment window if you want it. If you delay Part D beyond your window and do not have other creditable drug coverage, you will owe a late enrollment penalty on your Part D premium for as long as you have Medicare. The penalty is one percent of the national average Part D premium for each month you were late.

What if I am still working and do not want Medicare yet?

You can decline Medicare if you have employer coverage with 20 or more employees. However, you must still sign up for Part A during your enrollment window to avoid a penalty. When you leave your job, you have eight months to sign up for Part B without penalty under the Special Enrollment Period.

Can I change my mind after I sign up?

Yes, during your initial enrollment period. You have until the end of the month following the month your coverage begins to make changes — for example, to add Part D or switch to a different plan. After that, changes are limited to specific times of year during the annual enrollment period.