Where you sign up depends on when you turn 65 and whether you already get Social Security
You sign up for Medicare through Social Security, Medicare.gov, or your local Social Security office — not through your doctor or insurance company. The place you go depends on three things: whether you are already collecting Social Security, whether you are turning 65 soon, and whether you missed your first chance to sign up. Most people sign up online at Medicare.gov in about 15 minutes. Some need to visit an office or call. A few have to fix a missed important date.
The important date matters because Medicare charges a penalty if you sign up late without a valid reason. The penalty is permanent — it stays on your bill for life. That is why knowing your important date and which route to use now saves money later.
Key Takeaways
- If you already get Social Security, Medicare.gov will show you a sign-up option when you log in, and you can enroll in minutes without visiting an office.
- If you do not get Social Security, you must sign up through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
- Your important date is three months before the month you turn 65, the month you turn 65, and three months after — a seven-month window called your Initial Enrollment Period.
- If you miss that window and do not have a valid reason (like still working with employer coverage), you will pay a permanent penalty on top of your monthly premium.
- You can sign up any time after you turn 65, but the penalty grows the longer you wait, so acting during your window or when ready after is cheaper than waiting years.
The online route: Medicare.gov if you already get Social Security
If you already collect Social Security, the fastest way is to log into your Social Security account at ssa.gov, then go to Medicare.gov and sign in with the same username. Medicare will show you a button to enroll. You choose which parts of Medicare you want (usually Part A and Part B), pick a plan if you want Part D prescription coverage, and finish in one sitting.
You do not need to mail anything, call anyone, or visit an office. The whole process takes 10 to 15 minutes. Your coverage starts the first day of the month you turn 65, as long as you sign up during your Initial Enrollment Period — the three months before you turn 65, the month you turn 65, and the three months after.
If you already get Social Security but have not created an online account yet, create one at ssa.gov first. It takes a few minutes and requires your Social Security number, date of birth, and an email address. Then you can sign up for Medicare the same way.
The phone and office routes if you do not get Social Security
If you do not collect Social Security yet, you cannot sign up through the Social Security website. Instead, you sign up directly with Medicare by phone or in person. Call 1-800-MEDICARE (1-800-633-4227) Monday through Friday, 8 a.m. to 8 p.m. Eastern time. A representative will ask you questions about your income, citizenship, and which parts of Medicare you want, then enroll you over the phone.
You will need your Social Security number, date of birth, and information about any current health insurance you have. The call usually takes 20 to 30 minutes. Coverage starts the first day of the month you turn 65 if you call during your Initial Enrollment Period.
If you prefer to sign up in person, find your local Social Security office at ssa.gov/locator. Walk in during business hours with your Social Security card, proof of citizenship (passport, birth certificate, or naturalization papers), and proof of residency (a recent utility bill or lease). A staff member will enroll you on the spot. Bring these documents even if you think you might not need them — offices sometimes ask for them and sometimes do not, depending on what is already in your file.
What happens if you miss your Initial Enrollment Period
Your Initial Enrollment Period is seven months long: three months before you turn 65, the month you turn 65, and three months after. If you do not sign up during those seven months, you can still sign up later, but you will owe a penalty.
The penalty for Part B (doctor and outpatient care) is 10 percent of the standard premium for each full year you were may be able to access but not enrolled. If the standard Part B premium is $165 a month and you waited two years, you would pay an extra $33 a month for life. The penalty for Part D (prescription drugs) works the same way: 1 percent of the national average premium for each month you were late.
The penalty does not go away. Even if you sign up five years later, you still pay it every month. The only way to avoid it is to have had a valid reason for missing your important date — usually that you were still working and had health insurance through your job. If that is your situation, you have a Special Enrollment Period of eight months after your job coverage ends to sign up without penalty.
Signing up if you are still working or have employer coverage
If you turn 65 but still work and have health insurance through your job, you do not have to sign up for Medicare right away. You can delay without penalty as long as your employer has 20 or more employees and you are actively working. This is called having a valid reason for late enrollment.
When you leave your job or lose the coverage, you have eight months to sign up for Medicare without owing a penalty. That eight-month window is your Special Enrollment Period. You sign up the same way — through Medicare.gov, by phone, or in person — but you will need to show proof that you had employer coverage (a letter from your employer or a copy of your insurance card).
If you sign up after those eight months are up, the penalty applies. So if you leave your job in June, you have until the end of February of the next year to sign up penalty-free. After that, the clock starts on late-enrollment penalties.
Documents and information you will need
| What You Need | Why | Where to Get It |
|---|---|---|
| Social Security number | Medicare uses this to set up your account and match it to Social Security | Your Social Security card or tax return |
| Date of birth | To confirm you are turning 65 and to calculate your enrollment period | Your birth certificate, driver's license, or passport |
| Proof of citizenship | Medicare requires proof you are a U.S. citizen or permanent resident | Passport, birth certificate, naturalization papers, or green card |
| Current insurance information (if you have it) | To coordinate coverage and avoid gaps | Your insurance card or policy documents |
| Employer coverage letter (if still working) | To prove you have a valid reason for late enrollment if you miss your important date | Your employer's HR or benefits department |
If you sign up online, you will not need to show documents — Medicare.gov will verify your information against Social Security records. If you sign up by phone or in person, have these documents ready but know that the representative may not ask for all of them.
Common mistakes that cost money
The biggest mistake is waiting too long. Many people think they can sign up for Medicare whenever they want, then are surprised by a permanent penalty. Your Initial Enrollment Period is only seven months. Mark your calendar three months before you turn 65 and sign up then, or you risk paying extra forever.
The second mistake is not knowing you have a valid reason for late enrollment. If you are still working with employer coverage, you do not have to sign up at 65. But you have to tell Medicare about it when you do sign up, and you have to do it within eight months of losing that coverage. If you wait a year, the penalty applies even though you had a good reason.
The third mistake is signing up for the wrong parts. Most people need Part A (hospital) and Part B (doctor). Some also need Part D (prescriptions). Part C (Medicare Advantage) is optional and replaces Part A and B. Do not sign up for Part C by accident if you want Original Medicare. Ask the representative or read the Medicare.gov page carefully before you confirm.
Frequently Asked Questions
Can I sign up for Medicare before I turn 65?
Yes. Your Initial Enrollment Period starts three months before the month you turn 65. So if you turn 65 in September, you can sign up starting in June. Signing up early is smart because it gives you time to fix any problems before your coverage starts.
What if I do not have a Social Security account yet?
Create one at ssa.gov before you try to sign up for Medicare through Medicare.gov. It takes a few minutes and requires your Social Security number, date of birth, and email. Once your account is set up, you can sign up for Medicare the same day. If you cannot create an account online, call 1-800-MEDICARE and a representative will help you.
Do I have to sign up in person, or can I do it all online?
If you already get Social Security, you can do it entirely online at Medicare.gov. If you do not get Social Security, you can sign up by phone at 1-800-MEDICARE or in person at your local Social Security office. You do not have to visit an office unless you want to.
What if I miss my important date by a few weeks?
A few weeks past your important date still counts as late, and the penalty applies. Your Initial Enrollment Period is exactly seven months — three months before, the month of, and three months after you turn 65. The day after that window closes, late-enrollment penalties start. Sign up as soon as you realize you missed it to stop the penalty from growing.
Can I change my mind after I sign up?
Yes. You have until the end of the calendar year to change your Medicare plan choices. If you signed up in June and want to switch plans, you can do it anytime before December 31. After December 31, you are locked in until the next Open Enrollment Period in the fall.