Medicare enrollment is not automatic at 65, and missing the important date can cost you thousands in penalties

You do not automatically receive Medicare when you turn 65. You must take action to enroll. If you wait past your important date without a valid reason, you will pay a permanent penalty on your premiums for as long as you have Medicare — even if you enroll years later.

The rules differ depending on whether you are still working and covered by an employer plan. If you are retired or have no employer coverage, your initial enrollment window opens three months before the month you turn 65 and closes three months after. That is a seven-month window. If you miss it, you enter a General Enrollment Period each year from January 1 to March 31, but the penalty applies to any months you were uninsured.

If you are still working and your employer has 20 or more employees, you can delay enrollment without penalty as long as you enroll within eight months of losing that coverage. This is called the Special Enrollment Period. The protection only applies to employer coverage — coverage from a spouse's employer, Medicare Advantage plans, or Medigap policies do not count.

Key Takeaways

  • You must enroll in Medicare yourself during your seven-month initial window (three months before and three months after your 65th birthday month) or face a permanent penalty.
  • If you are covered by an employer plan with 20 or more employees, you can delay enrollment without penalty, but you must enroll within eight months of losing that job coverage.
  • Part A (hospital insurance) and Part B (medical insurance) have separate enrollment important date and separate penalties, so missing one does not protect you from the other.
  • The penalty is 10 percent of your Part B premium for each full year you were not enrolled, added to your premium permanently.
  • You enroll through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

When your initial enrollment window opens and closes

Your initial 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 enroll any time during this period — there is no advantage to enrolling early, and no disadvantage to waiting until the last month, as long as you enroll before the important date.

The enrollment window closes on the last day of the third month after your birthday month. If you turn 65 in June, your important date is September 30. If you turn 65 on June 30 or June 1, the important date is the same. The month of your birthday is what matters, not the specific date.

If you miss this window and have no employer coverage, you enter the General Enrollment Period, which runs January 1 through March 31 each year. Coverage under this period begins July 1 of that year. But you will owe a penalty for every month between when you should have enrolled and when you actually do.

The employer coverage exception and the eight-month rule

If you are still working and covered by your employer's health plan, you do not have to enroll in Medicare at 65. You can stay on your employer plan and delay Medicare enrollment without penalty, as long as your employer has 20 or more employees. This protection is called the Special Enrollment Period.

The eight-month clock starts the month your employer coverage ends — either because you retire, lose your job, or your employer drops the plan. You have eight months from that date to enroll in Medicare without penalty. If you wait longer, you owe the penalty for the months you were uninsured.

This protection applies only to employer group health plans. It does not explore if you are covered by Medicare Advantage, Medigap, COBRA, retiree health plans, or a spouse's employer plan (unless you are also covered by your own employer plan). If you have any doubt whether your coverage qualifies, call 1-800-MEDICARE and describe your plan to a representative.

Part A and Part B penalties are separate

Medicare has two main parts: Part A covers hospital stays, and Part B covers doctor visits and outpatient care. Each has its own enrollment important date and its own penalty. You can enroll in Part A without Part B, or delay Part B while enrolling in Part A, but each month you are not enrolled in Part B (when you should be) adds to your penalty.

Most people do not owe a premium for Part A if they or their spouse paid Medicare taxes for at least 10 years. But Part B has a monthly premium, and the penalty is 10 percent of that premium for each full year you were not enrolled. If the Part B premium is $165 per month and you delay enrollment by two years, your penalty is 20 percent — $33 per month added to your premium for life.

The penalty applies even if you eventually enroll. It does not go away after a certain number of years. If you delay five years, you pay the penalty for the rest of your life.

How to enroll and what documents you need

You can enroll 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 enrollment is the fastest — you can complete it in 10 to 15 minutes if you have your information ready.

Have your Social Security number, date of birth, and citizenship or immigration status ready. If you are enrolling in Part B, you will also need information about any current health coverage (employer plan, Medicaid, Veterans benefits, or other coverage). If you are a federal employee or railroad retiree, have that information available too, as it affects your enrollment.

You do not need to bring original documents to enroll online or by phone. Medicare will verify your information with Social Security. If you enroll in person at a Social Security office, bring your Social Security card and a photo ID.

What happens if you miss your important date

If you miss your initial enrollment window and have no employer coverage, you can still enroll during the General Enrollment Period (January 1 to March 31 each year), but coverage does not start until July 1 of that year. You will have a gap in coverage from when you turned 65 until July 1.

During that gap, you owe the Part B penalty. The penalty is 10 percent of the Part B premium for each full year you were not enrolled. A "full year" means 12 months. If you were uninsured for six months, you do not owe a penalty for that period — only for complete 12-month periods. But if you were uninsured for 13 months, you owe the penalty for two full years.

The penalty is permanent. It stays on your premium for the rest of your life, even if you later enroll. There is no way to remove it except in rare cases where you can prove you did not understand the important date — for example, if you were out of the country and received no notice. Social Security can waive the penalty in these situations, but you must request a waiver in writing and provide evidence.

Delaying Part B if you have employer coverage

If you are still working and covered by an employer plan, you should enroll in Part A at 65 (since there is usually no premium) but you can delay Part B without penalty. Part B is for doctor visits and outpatient care, which your employer plan likely covers.

When you leave your job or lose your employer coverage, you have eight months to enroll in Part B without penalty. The eight-month clock starts the month your coverage ends. If you enroll within that window, no penalty applies, even if you delay for the full eight months.

If you are unsure whether your employer plan qualifies for this protection, enroll in Part A anyway. Part A has no premium for most people, and enrolling in Part A does not force you to enroll in Part B. You can enroll in Part B later during your eight-month window.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65?

Your enrollment window opens three months before your 65th birthday month, so yes. For example, if you turn 65 in June, you can enroll starting in March. There is no advantage to enrolling early — coverage begins the same month regardless of when during your window you enroll.

What if I am still working at 65 and do not want Medicare?

If your employer has 20 or more employees, you can stay on your employer plan and skip Medicare. When you leave that job, you have eight months to enroll in Part B without penalty. Enroll in Part A at 65 anyway, since it usually has no premium and protects you if your employer coverage ends unexpectedly.

Do I have to enroll in Part D (prescription drug coverage) at 65?

Part D is optional, but if you go without it and later enroll, you owe a penalty for each month you were not covered. The penalty is about 1 percent of the national average Part D premium per month of delay. If you have other prescription coverage (employer plan, Medicaid, Veterans benefits), you may not owe a penalty.

What if I miss the important date by one day?

Missing the important date by one day means you miss your initial enrollment window. You can enroll during the next General Enrollment Period (January 1 to March 31), but coverage does not start until July 1, and you owe a penalty for the months you were uninsured. There is no grace period.

Can the penalty be removed if I have a good reason for missing the important date?

Social Security can waive the penalty only in limited situations — for example, if you were out of the country and did not receive notice, or if you received incorrect information from a government office. You must request a waiver in writing and provide evidence. Contact your local Social Security office to ask about a waiver.