CMS-40B

Request for Enrollment in Medicare Part B (Medical Insurance)

Agency
CMS
Revision
07/2025
Fillable fields
47
Pages
3
Official source
CMS form page
Checked
October 20, 2026
Fill CMS-40B online
Page 1 of form CMS-40B

Form CMS-40B: Request for Enrollment in Medicare Part B (Medical Insurance)

Form CMS-40B is the Request for Enrollment in Medicare Part B (Medical Insurance) from the Centers for Medicare & Medicaid Services, part of the U.S. Department of Health and Human Services. The form says it is for people who already have Medicare Part A and want to sign up for Part B. Without Part A, the form says not to complete it and to contact Social Security to apply for Medicare for the first time.

The form lists three times it can be used: during your Initial Enrollment Period, during the General Enrollment Period from January 1 to March 31 each year, or if you are eligible for a Special Enrollment Period. It has three sections: basic information, questions about employer or union group health plan coverage with a choice of coverage start date, and signatures.

The completed, signed form goes to your local Social Security office by mail or fax, and the CMS page adds that it can also be submitted in person there. You can fill it out free in your browser on this page and download the result without an account.

Top of page 1 of Form CMS-40B: Request for Enrollment in Medicare Part B (Medical Insurance), as printed by CMS

What's on Form CMS-40B

Section 1: Basic information

Your Medicare Number, first, middle and last name and suffix, mailing address, phone number and email address.

Section 2, items 1 and 2: coverage questions

Yes or no: whether you have (or had) employer or union group health plan coverage since you turned 65, and whether you are (or were) an international volunteer for a non-profit that provided health coverage.

Section 2, item 3: dates

Start and end dates (mm/yyyy) of employment with an employer that provided coverage, of volunteer work outside the U.S., and of the health coverage itself, each with a Not ended box. A separate sheet can be attached for more space.

Section 2, item 4: asked to enroll

Whether an employer, health insurance provider or other entity asked or required you to enroll in Part B. If yes, the form asks you to explain how and why and include proof or documentation.

Coverage start date

If you enroll while still covered by a group health plan based on current employment, or in the first full month after that coverage, you pick the first day of the month you enroll or of any of the 3 months after.

Section 3: Signatures

Your signature and the date signed. If the form is signed by mark (X), a witness who knows the person applying signs too, with their name and date.

The form says all fields are required unless noted.

How to submit Form CMS-40B

  1. 1

    Check the form's conditions

    The form is for people who already have Part A, during the enrollment periods it lists. Without Part A, the form points to Social Security instead.

  2. 2

    Fill out Section 1

    Enter your Medicare Number, full name, mailing address, phone number and email address.

  3. 3

    Answer Section 2

    Answer the coverage questions. If you list employer coverage, the form says to have your employer fill out Form CMS-L564 and return it with your application.

  4. 4

    Choose a coverage start date

    If the coverage start date choice applies to you, check one box and, for a later month, write the month and year (mm/yyyy).

  5. 5

    Sign and date

    Sign and date Section 3. A form signed by mark (X) also needs a witness's name, signature and date.

  6. 6

    Send it to Social Security

    Mail or fax the signed form to your local Social Security office. The CMS page says it can also be submitted in person. Find an office at SSA.gov/locator.

Why fill Form CMS-40B on indox

You get the real form, filled in a browser tab, with nothing standing between you and the finished PDF.

  • Fill the form right in your browser, no software to install
  • Free to fill and free to download, with no account
  • The official blank straight from the CMS, not a copy someone retyped
  • Works on a phone, tablet or computer

Where it goes, enrollment periods and help

Where to send it

To your local Social Security office by mail or fax, or in person according to the CMS page. Find an office at SSA.gov/locator. The CMS address on page 2 is for comments on the form only, not for applications.

Enrollment periods

The form lists the Initial Enrollment Period, the General Enrollment Period from January 1 to March 31 each year, and a Special Enrollment Period if you are eligible.

Premiums

The form notes that Part B premiums are paid for every month you have the coverage. It does not list amounts.

Help with the form

Social Security: 1-800-772-1213, TTY 1-800-325-0778, with Spanish service by pressing 2. Free health insurance counseling is available from your State Health Insurance Assistance Program (SHIP) at shiphelp.org.

Other formats

Medicare information is available in large print, braille or audio. Visit Medicare.gov/about-us/accessibility-nondiscrimination-notice or call 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048.

Time to complete

The form estimates an average of 15 minutes per response, including reviewing the instructions and gathering the information.

Related forms

Who uses Form CMS-40B?

  • People who already have Part A

    Anyone who has Medicare Part A and wants to sign up for Part B (Medical Insurance) can use this form, according to the form and the CMS page.

  • Initial Enrollment Period

    The form lists your Initial Enrollment Period as one time to sign up for Part B with it. For timing details it points to Medicare.gov/basics/get-started-with-medicare.

  • General Enrollment Period

    The form also lists the General Enrollment Period, which it gives as January 1 to March 31 each year.

  • Special Enrollment Period

    People eligible for a Special Enrollment Period can use the form. With employer group health plan coverage, the form asks for its dates and for the employer to fill out Form CMS-L564.

  • Not for people without Part A

    The form says not to complete it if you don't have Part A. Instead, it says to contact Social Security to apply for Medicare for the first time.

The form is for people who already have Medicare Part A and want Part B. It names the times it can be used.

Official sources and the blank

Do it all with indox

View all 94 tools

Questions about Form CMS-40B

Can I use Form CMS-40B if I don't have Medicare Part A?

No. The form says not to complete it if you don't have Part A, and to contact Social Security to apply for Medicare for the first time.

Where do I send Form CMS-40B?

The form says to mail or fax the completed, signed form to your local Social Security office. The CMS page adds that you can also visit the office in person. Find one at SSA.gov/locator.

When can Form CMS-40B be used?

The form lists three times: your Initial Enrollment Period, the General Enrollment Period from January 1 to March 31 each year, and a Special Enrollment Period if you are eligible.

Do I also need Form CMS-L564?

Item 3 of Section 2 asks for dates of employment and health coverage, and says to have your employer fill out Form CMS-L564 (Request for Employment Information) and return it with your application.

Can I choose when my Part B coverage starts?

The form says yes if you enroll while still covered by a group health plan based on current employment, or during the first full month you are not enrolled in it. The choices are the first day of the month you enroll or of any of the 3 months after.

What if the applicant signs with a mark?

If the form is signed by mark (X), a witness who knows the person applying signs too, and enters their first and last name and the date signed.

Who can I call with questions about Form CMS-40B?

The form lists Social Security at 1-800-772-1213 (TTY 1-800-325-0778). It also points to your local SHIP at shiphelp.org for free health insurance counseling.