The 8-Month Special Enrollment Period
When your active employer coverage ends — whether through retirement, job loss, or reduced hours — you trigger an 8-month Special Enrollment Period (SEP) for Part B. During this window, you can enroll in Part B without paying the late enrollment penalty.
When the Clock Starts
Your 8-month window begins on the first day of the month after either:
- Your active employment ends, OR
- Your employer-sponsored coverage ends
Whichever happens first. COBRA coverage does not extend this window.
Required Documentation
To enroll in Part B during your SEP, you’ll need:
- Form CMS-40B — Application for Enrollment in Medicare Part B
- Form CMS-L564 — Request for Employment Information (filled out by your employer’s HR)
Submit both forms to Social Security in person, by mail, or fax. Online submission is now available at secure.ssa.gov/iCBPSP.
When Coverage Begins
Part B coverage typically begins the first day of the month after Social Security receives your application. You can request a delayed start date up to 3 months in the future, which is useful if you have employer coverage running through a specific date.
Critical Timing for California Retirees
If you’re retiring from a California employer, do not wait until your employer coverage ends to start the Part B paperwork. Contact Social Security at least 60 days before your last day of work to ensure smooth coverage transition without gaps.