Form CMS-40B at a glance
What it is: CMS-40B (07/2025): Request for Enrollment in Medicare Part B (Medical Insurance).
Who signs: Section 3: Signature(s) 1. Signature of applicant 2. Date signed (mm/dd/yyyy)
Where and when to file: Mail or fax your completed, signed form to your local Social Security office.
Use this form if you already have Medicare Part A and want to sign up for Part B (Medical Insurance). You can use this form to sign up for Part B during these times.
During your Initial Enrollment Period
During the General Enrollment Period from January 1-March 31 each year
If you're eligible for a Special Enrollment Period
What to bring and attach to Form CMS-40B
If you have (or did have) coverage through an employer or union group health plan since you turned 65, have your employer fill out the form CMS-L564 (Request for Employment Information) and return it with your application.
A filled-in Form CMS-40B example: signing up for Part B with no group health plan
How to fill out Form CMS-40B, box by box
Section 1: Basic information
Section 1: Basic information. All fields required unless noted.
Coverage through an employer and international volunteers
1. Do you have (or did you have) coverage through an employer or union group health plan since you turned 65? (If yes, complete item 3.)
Yes No Note: If you sign up for Part B, you must pay premiums for every month you have the coverage.
2. Are you currently (or were you) an international volunteer for a non-profit organization that provided health coverage to you? (If yes, complete item 3.) Yes No
Dates of employment (or volunteer work) and health coverage
3. Enter dates of employment (or volunteer work) and health coverage (enter dates as mm/yyyy).
Attach a separate sheet if you need more space.
Dates you (or your spouse) worked for an employer that provided health coverage: Start date, End date, Not ended
Dates you worked as a volunteer outside the U.S.: Start date, End date, Not ended
Dates of health coverage from employer (or non-profit organization): Start date, End date, Not ended
Asked or required to enroll in Part B
4. Has an employer, health insurance provider, or other entity asked or required you to enroll in Part B? (If yes, explain how and why in the space, and include proof or documentation with this form.) Yes No
Choose your coverage start date
Choose your coverage start date If you're enrolling in Medicare while you're still covered by a group health plan based on current employment (or during the first full month you're not enrolled in the group health plan), you can choose when your Medicare coverage will start.
Choose one: The first day of the month you enroll
The first day of any of the 3 months after you enroll.
Write the month and year you want coverage to start: (mm/yyyy)
Section 3: Signature of the applicant
Section 3: Signature(s) 1. Signature of applicant 2. Date signed (mm/dd/yyyy)
A witness, if the form is signed by mark (X)
If this form has been signed by mark (X), a witness who knows the person applying must also sign.
3. Name of witness (first and last name) 4. Signature of witness 5. Date signed (mm/dd/yyyy)
More rules for Form CMS-40B
Important: Do not send this form or any items with your personal information (such as claims, payments, medical records, etc.) to the PRA Reports Clearance Office.
If your situation is different
You don't have Part A
If you don't have Part A, don't complete this application. Contact Social Security to apply for Medicare for the first time.
Common questions about Form CMS-40B
Where do I file it?
Mail or fax your completed, signed form to your local Social Security office. Find an office near you at SSA.gov/locator. Submit your completed and signed form by mail, fax, or by visiting your local Social Security office in person.[2]
Where to get help with Form CMS-40B
Phone: Call Social Security at 1-800-772-1213. TTY users call 1-800-325-0778.
State Health Insurance Assistance Program (SHIP): Visit shiphelp.org to get free, personalized, and unbiased health insurance counseling from your local SHIP.
Sources
[1] Form CMS-40B (07/2025), Request for Enrollment in Medicare Part B (Medical Insurance), Centers for Medicare & Medicaid Services (the Official source link on this page).
[2] cms.gov, submission_method (cms.gov). Accessed November 7, 2026.
