CENTERS FOR MEDICARE & MEDICAID SERVICES

Medicare Part B Enrollment Request (Form CMS-40B)

Ask Social Security to add Medicare Part B when the applicant already has Part A.

Form CMS-40B is the official request for someone who already has Medicare Part A and wants to sign up for Medicare Part B. The walkthrough routes the applicant through the enrollment window, coverage history, proof, and print-sign steps that apply to the current 07/2025 form.

Start the walkthrough View the official source

Average time

10-15 minutes

Difficulty

moderate

Best for

People who already have Medicare Part A and are ready to request Medicare Part B during an Initial, General, or Special Enrollment Period.

What this form stands for

Produce a current CMS-40B (07/2025) filled PDF ready for the applicant to print, sign, attach required evidence, and mail or fax to the local Social Security office.

Do not use CMS-40B if the applicant does not already have Medicare Part A or is outside the enrollment windows described in the official instructions.

What you'll need

The applicant's Medicare card and Medicare number
Mailing address, phone number, and email address
Employer or union coverage dates, if using the job coverage path
CMS-L564 from the employer for the job coverage path
Proof or documentation if an employer, insurer, or other entity required Part B enrollment

How the walkthrough is organized

Path check

Confirm the applicant already has Part A and is using a valid Part B enrollment window.

Basic information

Collect Medicare number, name, mailing address, phone number, and email address.

Coverage history

Route employer, union, or nonprofit volunteer coverage questions and dates only when they apply.

Required enrollment proof

Capture the explanation and proof reminder only when another entity asked or required Part B enrollment.

Coverage start choice

For the job coverage path, choose the printed coverage start option and collect the month/year only for the delayed start choice.

Print-sign handoff

Prepare the applicant signature date, witness lane when needed, attachments, and local Social Security office submission step.

Ready to start?

Docgle asks calm, plain-English questions and keeps the official source attached for review.

Start cms-40b-medicare-part-b-enrollment walkthrough