How to Complete Form CMS-40B
Form CMS-40B is the Application for Enrollment in Medicare Part B. It is used when enrolling in Part B outside of your Initial Enrollment Period, typically during a Special Enrollment Period.
Download Form CMS-40B
What Is Form CMS-40B?
Form CMS-40B is the official application to enroll in Medicare Part B (Medical Insurance). You use this form when you are enrolling outside of your Initial Enrollment Period — typically during a Special Enrollment Period (SEP) because you are losing employer group health coverage.
When Do You Need This Form?
- You delayed Part B enrollment because you had employer group health coverage
- You are now losing that employer coverage and want to enroll in Part B
- You are enrolling within 8 months of losing employer coverage
- You are applying for Part B for the first time after age 65
How to Complete CMS-40B
Section 1 – Your Information
- Full legal name as it appears on your Medicare card
- Medicare Claim Number (HICN) or Medicare Beneficiary Identifier (MBI)
- Date of birth
- Sex
- Current address and phone number
Section 2 – Enrollment Request
- Check the box for the type of enrollment (Initial, Special Enrollment Period, etc.)
- Indicate the reason for your Special Enrollment Period if applicable
- Requested effective date for Part B coverage
Section 3 – Signature
- Sign and date the form
- Your signature certifies the information is accurate
Submit With Form CMS-L564
When enrolling under a Special Enrollment Period based on employer coverage, you must submit CMS-40B together with Form CMS-L564 (Request for Employment Information). CMS-L564 must be completed and signed by your employer.
Where to Submit
Submit to your local Social Security Administration office:
- Mail to your local Social Security office
- Bring in person to a Social Security office
- Call SSA at 1-800-772-1213 to confirm fax options