You can sign up for Medicare at 65, but the exact timing matters for your costs

Medicare enrollment opens three months before the month you turn 65 and closes three months after. If you sign up during this seven-month window — called your Initial Enrollment Period — you avoid late penalties on most parts of the program. If you miss this window and do not have other coverage, you will pay a permanent surcharge on Part B (doctor visits) and Part D (prescription drugs) for as long as you have Medicare.

You do not have to sign up the moment you turn 65 if you are still working and covered by your employer's health plan. But you do need to understand the rules for your specific situation, because the penalty rules differ depending on whether you have group coverage through work or are uninsured.

Key Takeaways

  • Your Initial Enrollment Period runs for seven months: three months before you turn 65, the month you turn 65, and three months after.
  • If you miss this window and do not have employer coverage, you will pay a 10 percent surcharge on Part B for each year you were may be able to access but not enrolled, and a 1 percent surcharge on Part D for each month you went without coverage.
  • If you are covered by an employer plan with 20 or more employees, you can delay enrollment without penalty as long as you sign up within eight months of losing that coverage.
  • You can sign up through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • Part A (hospital insurance) has no monthly premium for most people, but Parts B and D do, and costs vary by income.

The seven-month enrollment window and what happens if you miss it

Your Initial Enrollment Period begins three months before the month you turn 65. For example, if you turn 65 in June, enrollment opens in March. It stays open through the month you turn 65 and closes three months after — so it would close in September. This gives you seven months total to sign up without penalty.

If you enroll during this window, your Part B coverage starts the first day of the month you turn 65 (or the month after, depending on when you sign up). Part A coverage is retroactive to age 65 if you sign up anytime during the Initial Enrollment Period.

If you do not sign up during this window and you do not have a valid reason to delay, you will owe a late enrollment penalty for as long as you have Medicare. For Part B, the penalty is 10 percent of the standard premium for each full year you were may be able to access but did not enroll. For Part D (prescription drug coverage), the penalty is 1 percent of the national base beneficiary premium for each month you went without coverage. These penalties do not go away.

When you can delay enrollment without penalty

You can delay enrollment past 65 without penalty if you are covered by a health plan through your current employer or your spouse's current employer. This is called creditable coverage. The employer must have at least 20 employees for this rule to explore.

If you have employer coverage, you have eight months after you lose that coverage to sign up for Medicare without penalty. This eight-month window is separate from your Initial Enrollment Period. For example, if you turn 65 while still employed and covered, you can wait until you retire or lose coverage, then sign up within eight months of that date without owing a penalty.

You will need to tell Medicare that you had employer coverage when you sign up. Bring a copy of your health plan documents or a letter from your employer stating the coverage dates and the number of employees.

How to sign up and what parts you need

You can sign up 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 through Medicare.gov is usually the fastest — you can complete it in 10 to 15 minutes if you have your Social Security number and birth date ready.

Medicare has four parts. Part A covers hospital stays, skilled nursing, hospice, and home health care. Part B covers doctor visits, outpatient care, and medical equipment. Part D covers prescription drugs. Part C (Medicare Advantage) is an alternative to Parts A and B offered by private insurers — you do not sign up for Part C separately; instead, you choose it in place of Original Medicare.

Part A has no monthly premium for most people who paid Medicare taxes while working. Part B has a monthly premium that changes each year; in 2024 the standard premium is $164.90, but it is higher if your income is above certain thresholds. Part D premiums vary by plan and by pharmacy. You will receive a notice in the mail before your coverage starts showing your premium amounts.

What happens if you turn 65 while still working

If you are still working and covered by your employer's health plan, you do not have to sign up for Medicare at 65. You can continue on your employer plan and sign up for Medicare later, as long as the employer has at least 20 employees. When you do retire or lose coverage, you have eight months to sign up without penalty.

However, you should still sign up for Part A at 65 even if you delay Part B, because Part A is usually free and it protects you if you have an unexpected hospital stay. You can sign up for Part A alone without signing up for Part B.

If your employer has fewer than 20 employees, the rules are different — you should sign up for Medicare when you turn 65 or within three months of losing coverage, whichever comes first. Contact Medicare directly to confirm the employee count if you are unsure.

Special enrollment periods if you miss the important date

If you miss your Initial Enrollment Period and do not have a valid reason to delay, you normally cannot sign up until the next General Enrollment Period, which runs January 1 through March 31 each year. Coverage would not start until July 1 of that year, leaving a gap in which you are uninsured and accruing penalties.

However, certain life events open a Special Enrollment Period that lets you sign up outside the normal windows. These include losing employer coverage, moving out of your plan's service area, or becoming a U.S. citizen. If any of these explore to you, contact Medicare to confirm you may have access to and to sign up.

Income-based premiums and how they affect your costs

Your Part B and Part D premiums are higher if your income is above certain thresholds. These thresholds are based on your modified adjusted gross income from two years prior. For 2024, if you file taxes individually and your income is above $97,000, you will pay a surcharge on top of the standard Part B premium. If you are married filing jointly, the threshold is $194,000.

The surcharge increases in steps as your income rises. At the highest income level, you could pay three times the standard Part B premium. Part D surcharges work the same way. You will receive a notice in the mail if your income puts you in a higher bracket, and you can appeal the information if you believe your income has changed since the two-year-old tax return Medicare used.

Frequently Asked Questions

What if I turn 65 in the middle of a month?

Your Initial Enrollment Period still runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. The exact day of your birthday does not change the window. For example, if you turn 65 on June 15, enrollment opens March 1 and closes September 30.

Can I sign up for Medicare before I turn 65?

You can sign up starting three months before the month you turn 65, but not earlier. Medicare will not process applications for people under 65 unless they have been receiving Social Security Disability Insurance (SSDI) for at least 24 months or have end-stage renal disease.

Do I have to sign up for Part D if I do not take prescription drugs?

You do not have to sign up for Part D at 65 if you do not take medications. However, if you sign up later, you will owe a 1 percent monthly penalty for each month you went without coverage. If you think you might need prescriptions in the future, it is usually cheaper to sign up now and pay the premium than to wait and pay the penalty later.

What if I am still working past 65 and my employer offers retiree health coverage?

Retiree health coverage from your employer counts as creditable coverage, so you can delay Medicare enrollment. When you retire and lose that coverage, you have eight months to sign up for Medicare without penalty. Bring documentation of your retiree coverage dates when you enroll.

Can I change my mind after I sign up?

Yes. You have until March 31 of the year after you first enroll to make changes to your coverage. After that, you can only change plans during the annual Open Enrollment Period (October 15 through December 7 each year) or if you may have access to for a Special Enrollment Period due to a life event.