You are not automatically enrolled in Medicare unless you are already receiving Social Security or Railroad Retirement Board benefits

Most people assume Medicare enrollment is automatic once they turn 65. It is not. You must take action to enroll unless you are already collecting Social Security or Railroad Retirement Board (RRB) benefits. If you are receiving either of those, Medicare Part A and Part B are enrolled for you automatically three months before the month you turn 65. If you are not receiving those benefits, you have to sign up yourself, and missing the important date costs you money for life.

The difference matters because the Social Security Administration and RRB handle the paperwork for you. You do not have to do anything. But if you are still working, or if you chose not to claim Social Security yet, Medicare does not know you exist until you tell it.

Key Takeaways

  • Automatic enrollment happens only if you are already receiving Social Security or Railroad Retirement Board benefits before you turn 65.
  • If you are not receiving those benefits, you must enroll in Medicare yourself during your Initial Enrollment Period, which runs three months before and three months after the month you turn 65.
  • Missing your Initial Enrollment Period triggers a permanent penalty on your Part B and Part D premiums, even if you enroll years later.
  • Working past 65 and having employer health coverage does not exempt you from enrollment important date unless your employer has 20 or more employees.
  • You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

Who gets automatically enrolled and when it happens

The Social Security Administration automatically enrolls you in Medicare Part A and Part B if you are receiving Social Security retirement or disability benefits (SSDI) when you turn 65. The enrollment takes effect the first day of the month you turn 65. You receive your Medicare card in the mail about two weeks before that date. The same process applies if you receive Railroad Retirement Board benefits.

This automatic enrollment is one-way only: it covers Part A (hospital insurance) and Part B (medical insurance). It does not cover Part D (prescription drug coverage) or Medigap or Medicare Advantage plans. You have to choose those separately, and missing those important date also carries penalties.

What happens if you are not receiving Social Security or RRB benefits

If you are still working, or if you delayed claiming Social Security, you do not get automatic enrollment. You must enroll yourself during your Initial Enrollment Period, which is seven months long: three months before the month you turn 65, the month you turn 65, and three months after. If you miss this window, you pay a permanent 10 percent increase on your Part B premium for every 12 months you were may be able to access but not enrolled. The penalty stays with you for life, even if you enroll later.

The same penalty applies to Part D (prescription drug coverage). If you go 63 days or longer without coverage and later enroll, you pay an extra amount each month based on how long you went without it. These penalties do not go away.

The employer coverage exception

If your employer has 20 or more employees and you are covered under their health plan, you can delay Part B enrollment without penalty. You have eight months after your employment ends or your coverage ends, whichever comes first, to enroll in Part B without triggering the late-enrollment penalty. You must enroll during that eight-month window or face the permanent 10 percent penalty.

This exception applies only to Part B. Part A (hospital insurance) has no employer exception — you should still enroll in Part A even if you have employer coverage, because Part A is usually free and covers hospital stays that employer plans may not fully cover.

How to enroll if you are not automatically enrolled

You can enroll online at Medicare.gov using your Social Security number and date of birth. The online process takes about 10 minutes. You can also call 1-800-MEDICARE (1-800-633-4227) and speak to a representative, or visit your local Social Security office in person. Social Security offices are listed on the Social Security Administration website by zip code.

When you enroll, have your Social Security number, date of birth, and citizenship or immigration status ready. If you are enrolling in Part D or a Medicare Advantage plan at the same time, have a list of your current medications or doctors, because some plans restrict which drugs and providers they cover.

What to do if you missed your enrollment important date

If you missed your Initial Enrollment Period and do not have an exception, you can still enroll, but you will pay the permanent penalty. The penalty is 10 percent of the Part B premium for each 12-month period you were may be able to access but not enrolled. If the standard Part B premium is $164.90 per month and you waited three years to enroll, your penalty would be 30 percent, raising your premium to about $214 per month for life.

You can enroll during the General Enrollment Period, which runs January 1 through March 31 each year. Coverage begins July 1 of that year. There are also Special Enrollment Periods for certain life events — losing employer coverage, moving out of your plan's service area, or changes in your immigration status — that may let you enroll without penalty. Contact Medicare to learn about your situation qualifies.

Part D and Medigap important date are separate from Part A and Part B

Even if you are automatically enrolled in Part A and Part B, you must choose Part D (prescription drug coverage) or a Medicare Advantage plan separately. Your Initial Enrollment Period for Part D is the same seven-month window as Part B: three months before, the month of, and three months after you turn 65. If you miss it and do not have creditable coverage (coverage that is at least as good as Medicare's), you pay a penalty each month you are enrolled in Part D later.

Medigap (supplemental insurance sold by private insurers) has its own enrollment window. You have six months from the date you enroll in Part B to buy a Medigap policy without the insurer being able to deny you or charge you more based on health conditions. After that window closes, insurers can refuse to sell you a policy or charge higher premiums.

Frequently Asked Questions

Do I have to enroll in Medicare if I am still working at 65?

You must enroll in Part A (hospital insurance) even if you are working, because it is usually free and covers hospital stays. For Part B (medical insurance), you can delay without penalty only if your employer has 20 or more employees and you are covered under their health plan. If your employer has fewer than 20 employees, you must enroll in Part B during your Initial Enrollment Period or pay a permanent penalty.

What if I turned 65 before I knew about the enrollment important date?

Contact Medicare when ready at 1-800-MEDICARE. If you are within your Initial Enrollment Period (three months before through three months after the month you turned 65), you can still enroll without penalty. If you are past that window, you may have a Special Enrollment Period if you have a may have access to life event, such as losing employer coverage. Medicare can review your situation and tell you what options are available.

Can I enroll in Medicare online?

Yes. Go to Medicare.gov and click "Enroll in Medicare." You will need your Social Security number, date of birth, and citizenship or immigration status. The process takes about 10 minutes. You can also call 1-800-MEDICARE or visit a local Social Security office.

If I am automatically enrolled, do I still have to choose a Part D plan?

Yes. Automatic enrollment covers Part A and Part B only. You must choose a Part D plan (prescription drug coverage) or a Medicare Advantage plan separately during your Initial Enrollment Period. If you do not choose by the important date and later enroll, you pay a penalty each month you are enrolled in Part D.

What happens if I enroll late and do not know about the penalty?

The penalty applies whether you know about it or not. It is calculated based on how long you were may be able to access but not enrolled, and it stays on your premium for as long as you have Medicare. There is no way to remove it after the fact. This is why enrolling during your Initial Enrollment Period is important.