Medicare sign-up happens separately from Social Security, but the timing matters because you can face penalties if you miss certain important date

Medicare and Social Security are two different programs run by two different agencies. Social Security is income; Medicare is health insurance. You do not automatically get Medicare when you claim Social Security, and you do not sign up for Medicare through Social Security's website or offices. Instead, you sign up through Medicare.gov, by phone, by mail, or in person at a Social Security office — but the rules about when you must sign up are tied to your Social Security decisions.

The key date is the month you turn 65. You have a seven-month window centered on that month — three months before, the month itself, and three months after — to sign up for Medicare Part A (hospital insurance) and Part B (medical insurance) without penalty. If you delay past that window and you do not have other may have access to coverage, you will pay a permanent surcharge on your Part B premium for as long as you have Medicare.

Most people become may be able to access for Medicare at 65, but some people under 65 can sign up if they have received Social Security Disability Insurance (SSDI) for 24 months, or if they have end-stage renal disease or ALS. The rules for those groups are different and are explained on Medicare.gov under "Who Can Get Medicare."

Key Takeaways

  • You must sign up for Medicare through Medicare.gov, by calling 1-800-MEDICARE, or in person — not through Social Security, even though the important date is tied to when you turn 65.
  • Your seven-month sign-up window runs from three months before you turn 65 through three months after, and missing it costs you a permanent 10% increase in your Part B premium for each year you were late.
  • If you are still working and have health insurance through your employer, you may be able to delay Part B without penalty, but you must tell Medicare about your coverage when you do sign up.
  • Part A (hospital insurance) is usually free if you or your spouse paid Medicare taxes for at least 10 years, but Part B (medical insurance) has a monthly premium that changes each year.
  • You can change your Medicare coverage choices once per year during the annual enrollment period from October 15 to December 7.

The three-month window before and after you turn 65

Medicare's initial enrollment period is seven months long and centers on your 65th birthday month. If you turn 65 in June, your window opens on March 1 and closes on September 30. You can sign up anytime during those seven months, and your coverage will begin on the first day of the month you turn 65 or the first day of the month after you sign up, whichever is later.

If you sign up during the three months before your birthday month, your coverage starts the month you turn 65. If you sign up in your birthday month or after, your coverage starts the first of the following month. For example, if you turn 65 on June 15 and sign up on July 10, your Medicare coverage begins August 1.

Missing this window triggers a late enrollment penalty. For Part B, the penalty is 10% of the standard premium amount for each full year you were may be able to access but not enrolled. That penalty stays on your premium for as long as you have Medicare. For Part D (prescription drug coverage), the penalty is 1% of the national base beneficiary premium for each month you were late, also permanent.

When you can delay Part B without a penalty

You can postpone Part B enrollment past your initial seven-month window without penalty if you have creditable coverage — health insurance through your current employer or your spouse's current employer. The coverage must be active and must cover at least as much as Medicare Part B does. You do not need to delay Part A; you can sign up for Part A during your initial enrollment period even if you delay Part B.

To use this exception, you must be actively working (or your spouse must be) and enrolled in the employer plan. Once you leave that job or lose the employer coverage, you have eight months to sign up for Part B without penalty. This eight-month period is called your Special Enrollment Period.

When you do sign up for Part B after delaying, you must tell Medicare about your employer coverage. Bring your insurance card or a letter from your employer's benefits department that states the coverage is creditable. Medicare uses this information to confirm you may have access to for the exception and to set your enrollment date correctly.

How to sign up for Medicare

You have four ways to sign up: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), by mail, or in person at a Social Security office. The online method is fastest; you can complete it in about 10 minutes if you have your Social Security number and information about any current health coverage.

To sign up by phone, call 1-800-MEDICARE. The line is open 24 hours a day, seven days a week. A representative will ask for your name, date of birth, Social Security number, and information about any employer coverage you have. The call usually takes 15 to 20 minutes.

To sign up by mail, read the "process for Enrollment in Part A and/or Part B" (Form CMS-40B) from Medicare.gov, fill it out, and mail it to the address on the form. Processing takes two to four weeks. To sign up in person, visit your local Social Security office with your Social Security card, proof of citizenship or legal residency, and proof of age. You can find your nearest office at ssa.gov/locator.

Part A and Part B: what they cover and what they cost

Part A covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health services. Most people do not pay a monthly premium for Part A if they or their spouse paid Medicare taxes for at least 10 years (40 quarters). If you do not meet that requirement, you can still buy Part A, but the premium varies based on how many quarters of coverage you have.

Part B covers doctor visits, outpatient care, medical equipment, and preventive services. Part B has a monthly premium that you pay whether you use it or not. The standard premium for 2024 is $164.90 per month, but it changes each year and may be higher if your income is above a certain threshold. Higher-income beneficiaries pay an additional amount called an Income-Related Monthly Adjustment Amount (IRMAA).

When you sign up, Medicare will tell you the exact premium you will pay based on your income from two years prior. You can see current premium amounts on Medicare.gov under "Costs at a Glance."

Part D and Medigap: prescription drugs and supplemental coverage

Part D is prescription drug coverage, and it is optional but recommended. If you do not sign up for Part D when you first become may be able to access and you do not have other creditable drug coverage, you will pay a permanent penalty when you do enroll. The penalty is 1% of the national base beneficiary premium for each month you were late.

You sign up for Part D separately from Part A and Part B. You can sign up on Medicare.gov, by phone, or through a private insurance company that offers Part D plans. Many Part D plans have a monthly premium, and all have a deductible and copayments.

Medigap (also called Supplement Insurance) is optional coverage sold by private insurers that pays some of the costs Medicare does not cover, such as copayments and coinsurance. Medigap is different from Medicare Advantage (Part C), which is an alternative to Original Medicare that some people choose instead of Part A and Part B. You sign up for Medigap directly through insurance companies, not through Medicare.

Changes you can make after you sign up

Once you are enrolled in Medicare, you can change your coverage during the annual enrollment period, which runs from October 15 to December 7 each year. Changes take effect January 1 of the following year. You can switch between Original Medicare and Medicare Advantage, change your Part D plan, or add or drop Medigap coverage.

If you experience a may have access to life event — such as losing employer coverage, moving out of your plan's service area, or getting married — you may be able to make changes outside the annual enrollment period. These are called Special Enrollment Periods, and they usually last 60 days from the event. Contact Medicare to confirm whether your situation qualifies.

Frequently Asked Questions

Do I have to sign up for Medicare if I am still working at 65?

You do not have to sign up for Part B if you have health insurance through your current employer and you are actively working. However, you should sign up for Part A, which is usually free. If you delay Part B, you must tell Medicare about your employer coverage when you eventually sign up to avoid a penalty.

What happens if I miss the seven-month window?

You can still sign up, but you will pay a permanent 10% increase on your Part B premium for each year you were late. For example, if you were three years late, your premium will be 30% higher for life. The only way to avoid this penalty is to have had creditable coverage through an employer during the time you were late.

Can I sign up for Medicare before I turn 65?

Your initial enrollment period begins three months before you turn 65, so yes. If you sign up during those three months, your coverage will start the month you turn 65. You cannot sign up earlier than that unless you are under 65 and have received SSDI for 24 months, have end-stage renal disease, or have ALS.

Is Medicare the same as Social Security?

No. Social Security is a retirement income program; Medicare is health insurance. You sign up for them separately, through different agencies, and the rules about when you must sign up are different. You can claim Social Security at 62 and delay Medicare until 65, or vice versa.

What if I do not have 10 years of Medicare tax history for Part A?

You can still buy Part A, but you will pay a monthly premium. The premium depends on how many quarters of coverage you have. You can see the current premium amounts on Medicare.gov, or call 1-800-MEDICARE to find out what you would pay based on your work history.