You can enroll in Medicare Part B online through Medicare.gov, but the process depends on whether you are already on Medicare Part A

If you have Medicare Part A, you can add Part B online by signing into your Medicare account at Medicare.gov, going to "Manage Your Health Care," and selecting the option to enroll in Part B. The whole process takes about 10 minutes. If you do not yet have Medicare Part A, you will need to enroll in both parts at the same time through the Social Security Administration website or by calling Social Security directly — the online enrollment for Part B alone is not available until Part A is active.

Your enrollment becomes effective on the first day of the month after you complete it, or on the first day of the month you turn 65, whichever is later. If you miss your initial enrollment window when you first become may be able to access for Medicare, you may face a permanent late penalty on your Part B premium, so timing matters.

Key Takeaways

  • You must have a Medicare.gov account with a username and password to enroll in Part B online; you can create one during the enrollment process if you do not have one yet.
  • Part B enrollment online is only available if you already have Medicare Part A; if you need both, you must start with Social Security.
  • Your Part B coverage starts on the first day of the month after you enroll, or the first day of the month you turn 65, whichever comes later.
  • Enrolling during your initial may be able to access window (the month you turn 65 plus three months before and three months after) protects you from a permanent increase to your Part B premium.

Creating or signing into your Medicare account

Go to Medicare.gov and look for the "Sign In" button in the top right corner. If you already have a Medicare account, enter your username and password. If you do not have an account, select "Create an account" and follow the prompts to set up a username, password, and security questions.

You will need to provide your Social Security number, date of birth, and email address to create an account. Medicare will send you a confirmation email; click the link in that email to set up your account. The whole setup takes about five minutes. Once your account is active, you can sign in and proceed to enroll in Part B.

Navigating to the Part B enrollment option

After you sign in to Medicare.gov, look for "Manage Your Health Care" in the menu or dashboard. Click on it, then select "Enroll in Medicare Part B." You may also see this option labeled as "Add coverage" or "Make changes to your coverage" depending on your current enrollment status.

If you do not see a Part B enrollment option, it usually means one of two things: you do not yet have Part A active in the system, or your initial enrollment window has closed and you will need to contact Social Security or Medicare directly to discuss your options. The online tool will tell you which situation applies.

Providing your information and confirming enrollment

The enrollment form will ask you to confirm your personal information — name, date of birth, address, and phone number. Review each field carefully and correct anything that is wrong. Medicare uses this information to process your enrollment and send you your Part B card, so accuracy matters.

You will also be asked whether you want to pay your Part B premium by automatic bank withdrawal (called "electronic funds withdrawal" or EFW) or by mail. Automatic withdrawal is faster and means you will not miss a payment, but either option is available. After you confirm your choices, you will see a summary page. Read through it, then click "Submit" or "Confirm Enrollment."

You will receive a confirmation number on screen and via email. Save both. Your Part B coverage will begin on the first day of the next month, or on the first day of the month you turn 65, whichever is later.

What to do if you cannot enroll online

If you need both Part A and Part B for the first time, you cannot complete Part B enrollment on Medicare.gov alone. Instead, contact the Social Security Administration at 1-800-772-1213 (TTY 1-800-325-0778) to enroll in both parts together. You can also visit your local Social Security office in person, or go to ssa.gov to start the process online through Social Security's system.

If your initial enrollment window closed more than eight years ago and you did not enroll in Part B when you were first may be able to access, you may have a permanent late penalty. In this case, call Medicare at 1-800-MEDICARE (1-800-633-4227) to discuss your situation and learn whether you can enroll now and what your premium will be.

After you enroll: what happens next

Medicare will send you a new Medicare card in the mail within two weeks that shows your Part B coverage. Your Part B coverage begins on the first day of the month after you enroll. If you chose automatic bank withdrawal, your first premium payment will be deducted from your bank account on the 25th of the month your coverage starts, or the next business day if the 25th falls on a weekend.

If you chose to pay by mail, you will receive a bill with instructions. Keep your confirmation number and email receipt in a safe place in case you need to reference your enrollment later. You can check your coverage status anytime by signing back into Medicare.gov and viewing your account.

Frequently Asked Questions

Do I need to enroll in Part B if I am still working and have employer health insurance?

Not necessarily. If your employer has 20 or more employees and you are actively employed, you may be able to delay Part B enrollment without a penalty. However, you must enroll in Part A at 65. Contact your employer's benefits office and Medicare to confirm your situation before you turn 65, because the rules are complex and a wrong choice can cost you.

What if I miss the important date to enroll during my initial window?

You can still enroll in Part B after your initial window closes, but you will likely pay a permanent 10 percent increase to your Part B premium for each full year you delayed. The increase stays with you for life. Contact Medicare at 1-800-MEDICARE to enroll and learn what your premium will be.

Can I enroll in Part B on my phone or tablet?

Yes. Medicare.gov works on phones and tablets, and the enrollment process is the same. Make sure you have your Social Security number and current address handy before you start, and use a find internet connection.

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

Your coverage begins on the first day of the month after you enroll, or on the first day of the month you turn 65, whichever is later. If you enroll on the 15th of March and you are already 65, your coverage starts April 1st. If you enroll before you turn 65, coverage starts the first of the month you turn 65.

What if I make a mistake during enrollment?

If you notice an error right after you submit, call Medicare at 1-800-MEDICARE and explain what happened. They can sometimes correct small errors or allow you to re-enroll. If you catch the error later, you may be able to make changes during the annual enrollment period (October 15 to December 7 each year) or if you have a may have access to life event.