You apply for Medicare Part B online through the Social Security Administration (SSA) website, usually during your Initial Enrollment Period or a Special/General Enrollment Period, and you’ll either complete a short online application (if you already have Part A) or include Part B in your full Medicare application.

Quick Scoop

  • You use the SSA website (not Medicare.gov) to sign up for Medicare Part B online.
  • If you already have Medicare Part A, there is a specific “Sign up for Part B only” pathway with its own online form.
  • You must apply during an allowed enrollment period (Initial, Special, or General) to avoid delays or potential late penalties.

1. Check when you can enroll

There are three main windows when people typically add Part B:

  • Initial Enrollment Period (IEP): 7‑month window around your 65th birthday (3 months before, the month of, and 3 months after).
  • Special Enrollment Period (SEP): If you delayed Part B because you (or a spouse) had qualifying employer coverage, you can usually sign up without penalty after that coverage ends.
  • General Enrollment Period (GEP): Every year from January 1 to March 31 if you missed IEP/SEP; coverage starts later and may include a late enrollment penalty.

2. Go to the correct SSA page

To apply online for Medicare Part B:

  • Go to the Social Security Administration’s Medicare signup area, then select the option to sign up for “Part B only” (for people who already have Part A).
  • The official page explains eligibility, enrollment periods, and provides a “Start application” button that launches the secure online form.

In practice, the online “Part B only” application is designed for people who already have Part A and need to add just the medical insurance component.

3. Create or log into your SSA account

You’ll need an online my Social Security account to complete the process:

  • Log in or create an account before starting the Part B application so SSA can verify your identity and link the request to your existing records.
  • Once logged in, you’ll choose “Sign up for benefits” or the dedicated option to sign up for Part B, then follow prompts to begin the application.

4. Complete the online Part B application

Within the online form, you generally:

  • Enter your Medicare number, indicate that you want to enroll in Part B, and confirm personal details like name, address, and contact information.
  • Review the digital equivalent of the Part B paper application (CMS‑40B) and electronically sign it at the end using an email-based signature step.

If you’re enrolling under a Special Enrollment Period after employer coverage:

  • You may need employer verification (similar to paper form CMS‑L564) to show that you had qualifying group health coverage and avoid late penalties.
  • Online workflows sometimes ask you to upload or provide details equivalent to these forms as part of your submission.

5. After you submit

Once you submit your application:

  • You’ll receive a confirmation and, later, a decision/coverage start date notice from Social Security, usually by mail or in your online account.
  • If approved, your Part B effective date will depend on which enrollment period you used (IEP, SEP, or GEP).

6. Latest news & discussion flavor

  • In 2025–2026, SSA has continued expanding online options, and many people are encouraged to enroll or add Part B online instead of walking into local offices, especially for SEPs after employer coverage.
  • Forum discussions often highlight that the online Part B process works smoothly if you have documents ready, but people sometimes run into issues if employer coverage forms are incomplete or if they miss their SEP window.

TL;DR: To apply for Medicare Part B online, go to SSA’s Medicare signup section, log into (or create) your my Social Security account, choose the “Sign up for Part B only” option if you already have Part A, complete the digital application (similar to form CMS‑40B), provide any required employer coverage information for a Special Enrollment Period, then electronically sign and submit.

Information gathered from public forums or data available on the internet and portrayed here.