The Basic Age Rule for Medicare

You can enroll in Medicare when you turn 65, regardless of your employment status or health history. This is the standard entry point for most people. Medicare Part A (hospital insurance) and Part B (medical insurance) both become available at 65, and you can sign up during the three months before your birthday, the month you turn 65, or the three months after.

If you delay enrollment past 65 without a valid reason, you may face a permanent penalty on your Part B premiums. The penalty is 10 percent for each full year you could have enrolled but did not. This penalty stays with you for life, so timing your enrollment correctly matters even if you do not plan to use Medicare when ready.

Key Takeaways

  • You become may be able to access for Medicare at age 65, and you should enroll during the seven-month window that starts three months before your birthday.
  • If you are still working and have employer health insurance at 65, you can delay Part B enrollment without penalty as long as your employer has 20 or more employees.
  • People under 65 with end-stage renal disease, ALS, or permanent disability can enroll in Medicare regardless of age.
  • Missing your enrollment window without a may have access to reason results in a permanent 10 percent premium increase for Part B.
  • You must be a U.S. citizen or permanent resident who has lived in the country for at least five consecutive years to enroll.

Exceptions: Medicare Before Age 65

Three groups of people under 65 can enroll in Medicare. The first is people with end-stage renal disease (ESRD), which means permanent kidney failure requiring dialysis or a transplant. You become may be able to access when ready once your condition is diagnosed, regardless of age.

The second group is people with ALS (amyotrophic lateral sclerosis, also called Lou Gehrig's disease). You become may be able to access the month your ALS diagnosis is confirmed, with no waiting period. The third group is people who have been receiving Social Security Disability Insurance (SSDI) for 24 consecutive months. After those 24 months pass, you can enroll in Medicare even if you are younger than 65.

If you fall into one of these categories, you will need to contact Social Security or Medicare directly to enroll, as the standard enrollment process does not explore to you. Your local Social Security office can walk you through the steps specific to your situation.

What Happens If You Miss Your Enrollment Window

Your initial enrollment period is seven months long: it starts three months before the month you turn 65 and ends three months after. If you do not enroll during this window, you enter what Medicare calls the "general enrollment period," which runs from January 1 to March 31 each year.

Enrolling during the general enrollment period means your coverage does not start until July 1 of that year, creating a gap. More importantly, you will owe the 10 percent Part B penalty for each year you were may be able to access but did not enroll. If you waited two years past 65 to sign up, your premium increases by 20 percent permanently.

The only way to avoid this penalty is to have had creditable coverage (health insurance that is at least as good as Medicare Part B) during the months you were not enrolled. If your employer provided this coverage, or if you were covered under a spouse's employer plan, you may be protected. You will need to provide proof of that coverage when you enroll.

Enrollment Timing and Your Birthday Month

Your initial enrollment period is tied to your birth month, not the calendar year. If you were born in March, your seven-month window opens in December and closes in June. If you were born in September, it opens in June and closes in December.

You can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. Online enrollment is usually the fastest option and takes about 10 minutes. If you enroll by phone or in person, allow extra time for processing.

Still Working at 65: When You Can Delay Part B

If you are still working and covered by your employer's health plan at 65, you do not have to enroll in Part B right away. You can delay Part B enrollment without penalty as long as your employer has 20 or more employees and you are actively working. This exception is called the Group Health Plan exception.

However, you should still enroll in Part A (hospital insurance) at 65 even if you delay Part B. Part A is usually free if you or your spouse paid Medicare taxes for at least 10 years, and enrolling in Part A does not trigger the Part B penalty clock.

When you leave your job or lose your employer coverage, you have eight months to enroll in Part B without penalty. This is called a special enrollment period. You will need to provide proof that you had employer coverage and proof that you have now lost it.

Citizenship and Residency Requirements

To enroll in Medicare, you must be a U.S. citizen or a permanent resident (green card holder) who has lived in the United States for at least five consecutive years. If you are a permanent resident, you will need to provide your green card or other proof of permanent residency when you explore.

If you are a citizen living abroad, you can still enroll in Medicare at 65, but Part B coverage does not extend outside the United States. Part A can cover some care in Canada and Mexico under specific circumstances, but you should review the rules before traveling.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65 if I am retired?

No, retirement alone does not lower the age requirement. You must be 65, or have ESRD, ALS, or have received SSDI for 24 months. If you retire before 65 and lose your employer coverage, you may be able to buy individual health insurance through the Affordable Care Act marketplace instead.

What if I was born on the first day of the month?

Medicare treats you as turning 65 on the first day of the month before your actual birthday. So if you were born on January 1, Medicare considers you 65 starting December 1. Your enrollment window opens in September and closes in March.

Do I have to enroll in Part B if I have other insurance?

If your other insurance is creditable coverage (employer coverage or retiree coverage that is at least as good as Medicare), you can delay Part B without penalty. Once that coverage ends, you have eight months to enroll in Part B. If you do not enroll within that window, the 10 percent penalty applies.

Can my spouse enroll in Medicare at a younger age?

No, each person must reach 65 (or meet one of the under-65 exceptions) to enroll. Your spouse's age does not affect your enrollment, and your enrollment does not affect theirs. You both enroll separately during your own enrollment periods.

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

You must be a permanent resident who has lived in the United States for at least five consecutive years. If you are on a visa or have temporary status, you are not may be able to access for Medicare. You may be able to buy private health insurance instead.