Medicare begins the first day of the month you turn 65, or the first day of the month after you turn 65 if you were born on the first of the month

Your Medicare Part A (hospital insurance) and Part B (medical insurance) coverage starts automatically on the first day of the month in which you turn 65, unless you were born on the first day of a month—then coverage starts the first day of the following month. You do not have to do anything to get Part A if you are already receiving Social Security benefits. If you are not yet receiving Social Security, you will need to contact Social Security to enroll in Medicare.

The timing matters because gaps between when you stop working and when Medicare starts can leave you uninsured. If you retire before 65, you may need temporary coverage through COBRA, a marketplace plan, or Medicaid while you wait. If you delay enrolling after you turn 65, you may face permanent penalties on your premiums.

Key Takeaways

  • Medicare Part A and Part B coverage begins on the first day of the month you turn 65, or the first day of the next month if you were born on the first of the month.
  • You are automatically enrolled in Part A if you receive Social Security; if not, you must contact Social Security to enroll in Medicare.
  • If you retire before 65, you will need separate health insurance until Medicare starts, such as COBRA or a marketplace plan.
  • Delaying enrollment after age 65 without a valid reason results in a permanent increase to your Part B and Part D premiums.

How the enrollment process works if you are not yet on Social Security

If you have not started collecting Social Security benefits by age 65, you must contact Social Security directly to enroll in Medicare. You can do this online at ssa.gov, by phone at 1-800-772-1213, or in person at your local Social Security office. Social Security will enroll you in Part A and Part B unless you decline Part B coverage.

The enrollment window opens three months before the month you turn 65 and closes three months after. If you enroll during this window, your coverage will start on the first day of the month you turn 65. If you miss this window and enroll later, your coverage will start the first day of the month after you enroll.

What happens if you are still working at 65

If you are still employed and covered by your employer's health plan when you turn 65, you may be able to delay Part B enrollment without penalty. This is called creditable coverage. Your employer's plan must be based on current employment (either your own or your spouse's), and your employer must have at least 20 employees.

If you have creditable coverage, you can wait to enroll in Part B until you or your spouse stops working or loses the employer coverage, whichever comes first. You then have eight months from the end of employment or coverage to enroll in Part B without penalty. Part A still begins at 65 unless you decline it.

If your employer plan does not may have access to as creditable coverage, you should enroll in Part B when you turn 65 to avoid late-enrollment penalties, even if you keep your employer plan. You can have both.

Timing for Part D (prescription drug coverage)

Part D coverage also begins the first day of the month you turn 65. You must enroll in a Part D plan during your initial enrollment window (three months before through three months after you turn 65) to avoid a permanent penalty on your premiums. If you have creditable prescription drug coverage through an employer or union plan, you may delay Part D enrollment without penalty, but you must notify Medicare that you have this coverage.

If you miss the initial enrollment window and do not have creditable coverage, you will pay a late-enrollment penalty for as long as you have Part D. The penalty is calculated based on how many months you went without coverage and increases each year.

What to do if you retire before 65

If you leave your job before turning 65, your employer health coverage usually ends. You will need to find temporary coverage to bridge the gap until Medicare starts. Your options include COBRA (which lets you keep your employer plan for up to 18 months but you pay the full premium plus a small fee), a health insurance marketplace plan, or Medicaid if your income is low enough.

COBRA is often expensive because you pay both the employer and employee share of the premium. Marketplace plans may be cheaper, especially if you may have access to for subsidies based on your income. Check healthcare.gov or your state's marketplace to see what plans and financial help are available in your area.

Do not go without coverage during this time. Medical bills from an accident or illness can be catastrophic, and you cannot enroll in Medicare early just because you are uninsured.

Late enrollment penalties and how they work

If you do not enroll in Part B when you first become may be able to access and do not have creditable coverage through an employer, you will pay a late-enrollment penalty for as long as you have Medicare. The penalty is 10 percent of the standard Part B premium for each full year you were may be able to access but not enrolled. If you delay for two years, your premium will be 20 percent higher than the standard amount.

This penalty is permanent—it does not go away once you enroll. The only exceptions are if you had creditable coverage through an employer or spouse's employer, or if you are a federal employee or retiree. If either applies to you, keep documentation of that coverage in case you need to prove it to Medicare later.

Frequently Asked Questions

Can I start Medicare before I turn 65?

No, with rare exceptions. You must be 65 or older to enroll in Medicare. The only exceptions are if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease or ALS (amyotrophic lateral sclerosis). If either applies, contact Social Security to learn when your Medicare coverage will start.

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

If you were born on the first day of the month, your Medicare coverage begins on the first day of the month after you turn 65, not the month you turn 65. For example, if you were born on January 1, your coverage starts February 1 when you turn 65.

Do I have to enroll in Part B, or can I just take Part A?

You are automatically enrolled in both Part A and Part B unless you decline Part B in writing. If you are still working and covered by an employer plan, you can decline Part B to avoid paying the premium, but you must do this before your coverage would normally start. If you decline and later want to enroll, you may face a late-enrollment penalty.

What if I move to another state after I turn 65?

Your Medicare coverage follows you to any state. You do not need to re-enroll or notify Medicare of a move. However, if you are in a Medicare Advantage plan (Part C), you may need to switch plans if your current plan does not serve your new state. You can make this change during the annual open enrollment period or if you move.

Can I delay Medicare if I am still working and healthy?

You can delay Part B if you have creditable coverage through your current employer, but Part A still begins at 65. If you do not have creditable employer coverage, delaying Part B will result in a permanent penalty. There is no financial advantage to delaying if you do not have employer coverage—you will straightforward pay more for the rest of your life.