How to Apply for Medicare Part B Online

You can explore for Medicare Part B through Medicare.gov, by phone, or in person at a Social Security office

Most people enroll in Medicare Part B when they first become may be able to access at 65, but you can also enroll later if you missed the important date. The online method through Medicare.gov is the fastest route — you can complete the form in about 15 minutes if you have your Social Security number and Medicare number ready. If you do not have internet access or prefer to speak with someone, you can call Social Security or visit a local office instead.

The process differs slightly depending on whether you are already receiving Social Security benefits. If you are, Part B enrollment happens automatically unless you actively decline it. If you are not yet receiving benefits, you will need to enroll in Part B separately, even if you are already on Medicare Part A.

Key Takeaways

You can enroll in Medicare Part B online at Medicare.gov, by calling 1-800-MEDICARE, or at your local Social Security office.
You will need your Social Security number, Medicare card or number, and proof of citizenship or legal residency to complete the process.
If you miss your initial enrollment window, you may face a permanent penalty on your Part B premium, so timing matters.
Part B coverage typically begins the first day of the month after you enroll, though this can vary depending on when you submit your request.

Step-by-step process for explore online at Medicare.gov

Go to Medicare.gov and select "Sign in with a Social Security number" or create a new account if you do not already have one. You will need to enter your Social Security number, date of birth, and email address. Once you are logged in, look for the option to "Enroll in Medicare Part B" — this is usually found under "Enrollment and Plans" or a similar menu heading.

The form will ask for your Medicare number (found on your Medicare card), your citizenship status, and whether you are currently working. Answer each question carefully, as incorrect information can delay your enrollment. At the end, you will see a summary of your choices. Review it for accuracy, then submit. You should receive a confirmation number when ready on screen — write this down or take a screenshot.

Medicare.gov will send you a confirmation email within a few minutes. Your Part B coverage will usually start on the first day of the month after you enroll, though if you enroll between the 1st and 15th of a month, coverage may begin that same month. Check your confirmation email for the exact effective date.

What documents and information you need before you start

Gather these items before you log into Medicare.gov: your Social Security number, your Medicare number (on your red, white, and blue Medicare card), your date of birth, and your current mailing address. You will also need to confirm your citizenship status — you must be a U.S. citizen or a lawful permanent resident who has lived in the United States for at least five years.

If you are still working and have employer health insurance, have that information available as well. Medicare will ask whether you are covered under a group health plan through your job, and your answer affects whether you face a late enrollment penalty. If you are unsure of your employment status for Medicare purposes, write down your employer's name and the date you started working there.

Enrollment important date and what happens if you miss them

Your initial enrollment period is the seven-month window that includes three months before the month you turn 65, the month you turn 65, and three months after. If you enroll during this window, you avoid a permanent penalty on your Part B premium. If you miss this window and do not have other health coverage (such as employer insurance or TRICARE), you will pay a 10 percent penalty for each year you delayed enrollment, added to your premium for life.

There are exceptions: if you were covered under an employer health plan when you turned 65, you have eight months after that coverage ends to enroll without penalty. The same applies if you are a federal employee or covered under TRICARE. If you fall into one of these categories, keep documentation of your coverage dates, as you will need to show it when you enroll.

You can enroll in Part B at any time after your initial period ends, but the penalty will explore unless you may have access to for an exception. There is no important date to enroll — you can do it at 75 or 85 — but the longer you wait, the more penalty you will pay.

Enrolling by phone or in person if you cannot use the website

Call 1-800-MEDICARE (1-800-633-4227) to enroll by phone. Have your Medicare number and Social Security number ready. The wait time varies by time of day and season, but calling early in the morning or mid-week usually means shorter holds. A representative will walk you through the same questions as the online form and will confirm your enrollment before the call ends. Ask for a confirmation number and write it down.

You can also visit your local Social Security office in person. Find the nearest office at ssa.gov or by calling 1-800-772-1213. Bring your Medicare card, Social Security card, and proof of citizenship (passport, birth certificate, or naturalization papers). An employee will complete the enrollment form with you and give you a receipt with your confirmation number. This method takes longer — plan for a 30-minute to one-hour visit — but it is useful if you have questions or need help with the form.

What to expect after you submit your enrollment

You will receive a confirmation number when ready (online) or before you leave (in person). Keep this number. Within one to two weeks, Medicare will mail you a new Medicare card that shows your Part B coverage. Your old card will still work until the new one arrives, so do not throw it away.

Your Part B premium will be deducted from your Social Security check each month, starting the month your coverage begins. If you are not yet receiving Social Security, Medicare will send you a bill. Check your first bill carefully — it should show your effective date and the amount you owe. If the amount seems wrong or the date is incorrect, call 1-800-MEDICARE to report it.

You will also receive a document called the "Medicare & You Handbook" in the mail. This handbook explains what Part B covers, your out-of-pocket costs, and how to find doctors who accept Medicare. Read the section on enrollment important date for other parts of Medicare (Part D for prescriptions, Part C for Medicare Advantage) so you know when to enroll in those as well.

Common mistakes to avoid when explore online

The most common error is entering the wrong date of birth or Social Security number. Double-check both before you submit. If you notice a mistake after you have submitted, call 1-800-MEDICARE right away — they can correct it, but it is faster if you catch it when ready.

Another mistake is assuming you are automatically enrolled in Part B. If you are not yet receiving Social Security benefits, Part B does not happen automatically — you must enroll yourself. Many people discover this too late and face a penalty. If you are turning 65 and not yet on Social Security, set a reminder to enroll in Part B during your initial enrollment period.

Do not wait until the last day of your enrollment period. If you enroll on the last day and there is a technical issue, you will miss the important date. Enroll at least one week before your period ends to give yourself a buffer.

Frequently Asked Questions

Can I enroll in Part B if I am still working at 65?

Yes. If you are still working and have health insurance through your employer, you can delay Part B enrollment without penalty. You have eight months after your coverage ends to enroll. Keep documentation of your employment and coverage dates, as you will need to show it when you eventually enroll.

What if I enrolled in Part B but want to cancel it?

You can drop Part B, but you will face a penalty if you do and later re-enroll, unless you have a may have access to reason. Contact Medicare at 1-800-MEDICARE to discuss your situation before you cancel. In most cases, it is better to keep Part B even if you have other coverage.

How long does it take for Part B coverage to start after I enroll online?

Coverage usually begins on the first day of the month after you enroll. If you enroll between the 1st and 15th of a month, coverage may start that same month. Your confirmation email will show your exact effective date.

Do I have to pay for Part B right away?

No. If you are receiving Social Security, the premium is deducted automatically from your check starting the month your coverage begins. If you are not on Social Security, Medicare will send you a bill. You have a grace period to pay, but do not ignore the bill — missing payments can result in a late fee.

What if the Medicare.gov website is not working?

Call 1-800-MEDICARE or visit your local Social Security office. Both can enroll you by phone or in person. You do not have to use the website — it is just the fastest option when it is available.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.