Form CMS-L564 is an employment information form from the Social Security Administration (SSA). It’s used in conjunction with Form CMS-40B when you apply for Medicare part B during a special ...

If you’re applying during an SEP, then you will need to submit an additional form along with CMS-40b. This additional form is CMS-L564, and you must fill it out and include it with your application.

From there, you can enroll in Part B by completing these forms: CMS-40B (Application for Enrollment in Medicare – Part B [Medical Insurance]) and CMS-L564 (Request for Employment Information).