Sign up for Medicare Part A during your initial enrollment period, which starts three months before the month you turn 65

Your initial enrollment period runs for seven months: three months before your 65th birthday, the month you turn 65, and three months after. If you sign up during this window, your Part A coverage begins on the first day of your birth month. This is the only time you get a penalty-free window, and missing it costs you money for as long as you have Medicare.

If you are already receiving Social Security or Railroad Retirement Board benefits when you turn 65, you are enrolled in Part A automatically — you do not need to do anything. Your coverage starts the month you turn 65. If you are not yet taking Social Security, you must sign up yourself during your initial enrollment period, either online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

The enrollment period matters because signing up late triggers a lifetime penalty. If you miss your initial enrollment period and do not have a valid reason for the delay, you pay an extra 10 percent of the Part A premium for twice the number of years you were late. That penalty stays with you permanently, even if you eventually sign up.

Key Takeaways

  • Your initial enrollment period is seven months long: three months before you turn 65, your birth month, and three months after.
  • If you are already on Social Security, Medicare Part A enrolls you automatically with no action needed on your part.
  • Missing your initial enrollment period without a valid reason results in a permanent 10 percent premium penalty for twice the years you delayed.
  • You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or at your local Social Security office.
  • If you are still working and covered by your employer's health plan, you may be able to delay Part A without penalty under certain conditions.

What happens if you miss your initial enrollment period

If you do not sign up during your seven-month window and you do not have a valid reason for the delay, you enter a general enrollment period that runs January 1 through March 31 each year. Coverage under this route begins July 1 of that year. This means if you miss your initial period by even one day and sign up in January, you wait until July for coverage to start — a gap of up to six months.

During that gap, you are uninsured for hospital care. Part A covers inpatient hospital stays, skilled nursing facility care, hospice, and some home health services. Without it, a single hospitalization can cost tens of thousands of dollars out of pocket.

The penalty itself is permanent. If you were supposed to sign up at 65 but did not sign up until age 68, you pay the 10 percent surcharge for six years (twice the three years you were late). That surcharge applies to every premium payment for the rest of your life, even after you turn 75 or 80.

Valid reasons to delay Part A without penalty

You can delay Part A past your initial enrollment period without triggering the penalty if you meet specific conditions. The most common reason is group health plan coverage through current employment. If you or your spouse is still working and covered by an employer or union health plan, you can delay Part A until you leave that job or lose the coverage, whichever comes first.

When you do sign up after leaving work, you have eight months from the date you lose coverage to enroll without penalty. This eight-month window is separate from your initial enrollment period and erases the late-signup penalty entirely. You will need documentation from your employer showing the dates you were covered and the reason coverage ended.

Other valid reasons for delay are rare and require proof. They include non-citizen status (you can delay until you become a citizen), living outside the United States for more than five years, or being covered under the Veterans Health Administration. If you believe you have a valid reason, contact Social Security before your initial enrollment period ends to ask about a special enrollment period.

How to sign up for Part A during your enrollment period

You have three ways to sign up: online, by phone, or in person. The fastest route is Medicare.gov. Go to the "Sign Up" section, create or log into your Medicare account, and follow the prompts. You will need your Social Security number, date of birth, and citizenship or immigration status. The online process takes about 10 minutes and you receive confirmation when ready.

If you prefer to speak with someone, call 1-800-MEDICARE (1-800-633-4227) between 8 a.m. and 8 p.m. Eastern time, seven days a week. Have your Social Security number and date of birth ready. The call center can enroll you over the phone and mail you a confirmation letter within two weeks.

You can also visit your local Social Security office in person. Find the nearest office at ssa.gov/locator. Bring your Social Security card, proof of citizenship (passport, birth certificate, or naturalization papers), and proof of residency (utility bill or lease). Processing takes longer in person — usually two to four weeks — but you walk out with a receipt.

What documents you need to have ready

Before you sign up, gather these documents so the process moves quickly. You will need your Social Security number, which appears on your Social Security card. You also need proof of citizenship or immigration status: a U.S. passport, birth certificate, naturalization certificate, or permanent resident card (green card). If you are signing up by phone or online, you do not need to mail these documents — you just state the information.

If you are signing up in person at Social Security, bring the originals or certified copies. You may also need proof of residency if Social Security cannot verify your address on file — a recent utility bill, lease, or mortgage statement works. If you are delaying Part A because of employer coverage, have your employer's group health plan documents or a letter from your employer stating the coverage dates and that you were an active employee.

Timing your sign-up to avoid gaps in coverage

The safest approach is to sign up during the first month of your initial enrollment period — three months before you turn 65. This gives you a buffer in case paperwork is delayed or Social Security needs additional information. If you sign up in month one of your seven-month window, your coverage is may provide to start on the first day of your birth month, with no gaps.

If you wait until your birth month or the three months after, you risk delays. Social Security processes applications in the order they arrive, and during busy seasons (October through December, when many people turn 65) processing can take four to six weeks. If your process arrives late in your enrollment period and processing is slow, your coverage start date may be pushed to the following month.

If you are still working and covered by an employer plan, do not wait until you actually leave your job to sign up. Instead, sign up during your initial enrollment period anyway — you will not be charged a penalty for having both coverages at once. When you leave work, notify Social Security of the date your employer coverage ended. Part A will become your primary coverage and your employer plan will become secondary, which is the correct order.

Part A costs and what is covered

Part A has no monthly premium if you or your spouse paid Medicare taxes for at least 40 quarters (10 years) while working. Most people who worked in the United States meet this requirement. If you do not, you can still enroll, but you pay a monthly premium — the amount varies based on how many quarters of Medicare tax you paid, ranging from roughly $280 to $505 per month in 2024, though this amount changes yearly.

Part A covers inpatient hospital stays, skilled nursing facility care after a hospital stay, hospice care, and some home health services. You pay a deductible for hospital stays — in 2024 this is $1,632 per benefit period, though the amount changes annually. You do not pay a deductible for skilled nursing, hospice, or home health. Part A does not cover outpatient doctor visits, prescription drugs, or routine preventive care — those are covered by Part B and Part D.

Frequently Asked Questions

What if I turn 65 and I am still working?

You can delay Part A without penalty if you are covered by your employer's group health plan. Sign up during your initial enrollment period anyway to avoid the penalty clock. When you leave work, you have eight months to notify Social Security that your coverage ended, and Part A becomes your primary coverage.

Can I sign up for Part A after I turn 65 if I missed my enrollment period?

Yes, but you will pay a permanent penalty unless you have a valid reason for the delay. You can sign up during the general enrollment period (January 1 through March 31 each year), but coverage does not start until July 1. The penalty is 10 percent of the Part A premium for twice the number of years you were late.

Do I need to sign up for Part B at the same time as Part A?

No. Part A and Part B have separate enrollment periods and separate penalties. You can sign up for Part A during your initial enrollment period and delay Part B if you are still working and covered by an employer plan. However, if you delay Part B without a valid reason, you will pay a penalty on that as well.

What if Social Security says I am already enrolled in Part A?

If you were receiving Social Security benefits before you turned 65, you were enrolled automatically. Call 1-800-MEDICARE to confirm your enrollment date and coverage start date. You do not need to do anything else — your coverage is active.

Can I change my mind after I sign up for Part A?

Yes, but only during your initial enrollment period. If you sign up and then change your mind within that seven-month window, you can request to be disenrolled. After your initial enrollment period ends, you can only drop Part A if you have other coverage that is primary, such as an active employer plan.