Medicare uses a specific employer form—CMS-L564, “Request for Employment Information” —when you enroll in Medicare Part B after having employer group health coverage.

What is the Medicare Part B employer form?

The “Medicare Part B employer form” most people talk about is CMS‑L564, officially called Request for Employment Information.

It is used together with your Part B application (CMS‑40B) to prove you had employer or union group health coverage and to help you avoid a late enrollment penalty when you delay Part B.

When do you need this form?

You typically need CMS‑L564 when:

  • You are enrolling in Medicare Part B during a Special Enrollment Period after:
    • You or your spouse (or in some cases a family member) have been covered by an employer group health plan, and
    • You are still working, or your employment/coverage ended within the last 8 months.
  • You already have Medicare Part A and are now choosing to add Part B because you are coming off employer group coverage.

Without this form (or other acceptable proof), Social Security may not grant a penalty‑free Special Enrollment Period.

How the employer form works (step-by-step)

Here is how CMS‑L564 is normally used:

  1. Get the form
    • The current version can be downloaded from Medicare/CMS (it is labeled CMS‑L564, “Request for Employment Information”).
 * Some brokers, HR departments, and Medicare education sites also link to the same CMS PDF.
  1. You complete Section A
    Section A is for the person signing up for Medicare Part B.

You generally provide:

 * Applicant’s name and Social Security Number
 * Employee’s name and SSN (if different from the applicant, such as a spouse)
 * Employer name and address, city, state, and ZIP code.
  1. Employer completes Section B
    Section B must be filled out and signed by the employer (or your spouse’s employer) that provides or provided the group health coverage.

The employer typically confirms:

 * Whether you were covered under an employer group health plan
 * The start date of your group health coverage
 * The end date of coverage, or notes if you are still actively employed and covered.
  1. Return the completed form to Social Security with your Part B application
    Once Section B is completed and signed, you include the CMS‑L564 with your CMS‑40B (Application for Enrollment in Medicare Part B) and submit both to Social Security—either online (by upload), by mail, or by dropping them off at a local office, depending on your situation.

Key details employers often get wrong

People sometimes run into delays because of employer mistakes on CMS‑L564:

  • Listing the start date of the current insurance carrier instead of the true start date of the group health plan.
  • Leaving employment or coverage dates blank when coverage has already ended.
  • Not signing or dating the form, or having someone sign who is not an authorized HR/benefits representative.

Medicare guidance and many specialist sites recommend double‑checking dates and signatures before you submit the form to avoid processing issues.

Where to get and how to pair the forms

You almost always see two forms together for this process:

  • CMS‑40B – Application for Enrollment in Part B
    • Used when you already have Part A and need to sign up for Part B.
  • CMS‑L564 – Request for Employment Information (the “employer form”)
    • Used as proof of creditable employer group health coverage so you can enroll in Part B under a Special Enrollment Period.

Medicare’s own forms page identifies CMS‑40B and CMS‑L564 as the standard pair for Part B enrollment when coverage is tied to employment.

TL;DR:
If you are looking for the “Medicare Part B employer form,” you are looking for CMS‑L564, Request for Employment Information. You fill out Section A, your (or your spouse’s) employer fills out Section B to verify group health coverage and employment dates, and you submit it together with CMS‑40B to Social Security so you can enroll in Part B—often using a Special Enrollment Period without a late enrollment penalty.

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