Medicare starts at age 65 for most people, but you may be able to join earlier if you have a disability, end-stage renal disease, or ALS

You become may be able to access for Medicare the month you turn 65, regardless of whether you are still working. If you were born on the first of the month, your coverage begins the month before. The enrollment window opens three months before the month you turn 65 and closes three months after — a seven-month window in total. If you miss this window and do not have other insurance that counts as "creditable coverage," you may pay a permanent penalty on your premiums.

You do not have to be retired to join Medicare at 65. You can keep working and have Medicare at the same time. If your employer has 20 or more employees, your employer's health plan is primary and Medicare is secondary — meaning the employer plan pays first. If your employer has fewer than 20 employees, Medicare becomes primary.

Some people join before 65. You can enroll at any age if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease (permanent kidney failure requiring dialysis or transplant) or ALS (amyotrophic lateral sclerosis). The rules for when your coverage starts depend on which category you fall into.

Key Takeaways

  • You become may be able to access for Medicare the month you turn 65, and you have a seven-month window to enroll without penalty.
  • If you have been on SSDI for 24 months, you can join Medicare before age 65 regardless of your age.
  • People with end-stage renal disease or ALS can join Medicare at any age, with coverage starting the month after they meet the medical criteria.
  • Missing your initial enrollment window can result in a permanent 10 percent increase to your Part B premium for each year you were not enrolled.
  • If you have creditable coverage through an employer or spouse's plan, you may be able to delay enrollment without penalty.

Enrollment at 65: the standard timeline

Your Initial Enrollment Period (IEP) runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, by mail, or in person at your local Social Security office.

If you enroll during this window, your Part A (hospital insurance) and Part B (medical insurance) coverage typically begins on the first day of the month you turn 65. If you were born on the first of the month, coverage begins the first day of the month before you turn 65. If you enroll after your birthday month, your coverage start date moves back one month for each month you delay — so enrolling in the month after your 65th birthday means coverage starts two months after you turn 65.

Delaying enrollment past your IEP without creditable coverage triggers a late enrollment penalty. Part B premiums increase by 10 percent for each full year you were not enrolled. This penalty is permanent and stays with you for life, even after you finally join. Part A does not usually have a penalty unless you delay more than 12 months after your IEP ends.

Joining before 65 with SSDI

If you receive SSDI, you automatically transition to Medicare after you have been on SSDI for 24 months. You do not need to explore separately. Your coverage begins the month after your 24-month period ends.

The 24-month clock starts the month your SSDI payments begin, not the month you applied. If you were approved retroactively and your first check covered months in the past, your 24-month period still starts from the month your payments officially began. You can contact Social Security to confirm the exact date your 24-month countdown started.

Once you transition to Medicare, you keep the same coverage even if you return to work and your SSDI payments stop. You remain on Medicare as long as you continue to pay premiums.

Joining before 65 with end-stage renal disease or ALS

You can join Medicare at any age if you have end-stage renal disease — meaning your kidneys function at less than 15 percent of normal capacity and you need dialysis or a transplant. You do not have to wait for a transplant; dialysis alone qualifies you. Your coverage begins the month after you start dialysis or the month after your transplant, whichever comes first.

If you have ALS, you become may be able to access for Medicare the month after you are diagnosed. You do not have to wait any length of time or meet any other criteria. Your doctor's diagnosis is sufficient.

For both conditions, you will need to enroll during your seven-month Initial Enrollment Period, which begins three months before the month your coverage is set to start. If you miss this window, the same late enrollment penalties explore as they do at age 65.

What happens if you miss your enrollment window

If you do not enroll during your seven-month Initial Enrollment Period and you do not have creditable coverage, you will face a permanent late enrollment penalty on your Part B premium. The penalty is 10 percent of the standard Part B premium amount for each full 12-month period you were not enrolled.

You can still enroll in Medicare after your window closes, but the penalty remains. For example, if you miss your window by two years and then enroll, your Part B premium will be 20 percent higher than the standard amount, and that increase stays with you permanently.

Part A (hospital insurance) does not usually carry a late enrollment penalty unless you delay more than 12 months after your Initial Enrollment Period ends. If you do face a Part A penalty, it is 10 percent of the standard premium for twice the number of years you were not enrolled.

Creditable coverage and delayed enrollment

Creditable coverage is health insurance that is at least as good as Medicare Part A and Part B combined. If you have creditable coverage through your employer, your spouse's employer, TRICARE (military coverage), or the Veterans Health Administration, you may be able to delay Medicare enrollment without penalty.

You have an eight-month Special Enrollment Period after your creditable coverage ends. During this window, you can enroll in Medicare without the late enrollment penalty. You will need to show proof that your previous coverage was creditable — usually a letter from your employer or insurance company stating the coverage dates and that it met Medicare's standards.

If you are still employed and your employer has 20 or more workers, you can delay Part B enrollment without penalty as long as you are covered by the employer's plan. Once you leave that job or lose the coverage, your Special Enrollment Period begins.

Enrollment methods and next steps

You can enroll in Medicare through several channels. The easiest is online at Medicare.gov, where you can create an account and submit your enrollment information directly. You can also call 1-800-MEDICARE (1-800-633-4227) to enroll by phone — representatives are available 24 hours a day, seven days a week.

You can enroll in person at your local Social Security office or by mail. If you enroll by mail, send your completed form to the address listed on the Medicare enrollment form, which you can read from Medicare.gov or request by phone. Mail enrollment takes longer, so submit it well before your important date if you choose this route.

When you enroll, have your Social Security number, birth date, and citizenship or immigration status ready. If you are enrolling based on a disability or medical condition, you will need documentation from your doctor or medical provider confirming your diagnosis and the date it began.

Frequently Asked Questions

What if I turn 65 but I am still working and have employer health insurance?

You can delay Part B enrollment without penalty as long as your employer has 20 or more employees and you are actively employed. Once you leave the job or lose coverage, you have eight months to enroll in Part B. You should still enroll in Part A at 65, since it has no premium and covers hospital stays.

Can I enroll in Medicare before I turn 65 if I do not have a disability?

No. The only ways to join before 65 are through SSDI (after 24 months), end-stage renal disease, or ALS. If you do not fall into one of these categories, you must wait until the month you turn 65.

What is the penalty if I enroll late?

Part B premiums increase by 10 percent for each full year you were not enrolled during your Initial Enrollment Period. This penalty is permanent. Part A does not usually have a penalty unless you delay more than 12 months after your enrollment window closes.

Do I lose Medicare if I go back to work after turning 65?

No. Once you are enrolled in Medicare, you keep your coverage even if you return to work or continue working. If your employer has 20 or more employees, the employer plan pays first and Medicare pays second. You remain responsible for your Medicare premiums.

How do I know if my current health insurance is creditable coverage?

Contact your insurance company or employer's benefits department and ask them to confirm in writing that your coverage meets Medicare's creditable coverage standards. They should provide a letter stating the coverage dates and that it is at least as good as Medicare Part A and Part B.