Transitioning From 20+ Employer Coverage to Medicare Without Gaps
Start Part B before or soon after active work ends. With a 20-plus employee employer, your employer plan is primary while you work and you can safely delay Part B. Once active work or employer coverage ends, you have an 8-month Special Enrollment Period — but it starts immediately, even if you take COBRA. Do not wait until COBRA ends to sign up for Part B.
Frequently Asked Questions
- When exactly does the 8-month SEP start?
- The 8-month Part B SEP starts when active employment ends or when the employer group health coverage ends — whichever comes first. If you take COBRA, the SEP clock is already running. COBRA does not extend or restart the SEP.
- Does COBRA extend my Part B enrollment window?
- No. Medicare.gov is explicit: the SEP starts when active work or coverage ends, even if you choose COBRA. Waiting until COBRA ends before signing up for Part B is one of the most common causes of unexpected Part B penalties.
- How do I coordinate Part B enrollment with my employer coverage ending to avoid a gap?
- Contact Social Security a few months before your employer coverage ends and request a Part B start date aligned with that end date. You can typically request a Part B start date up to 3 months in the future so coverage is continuous or has minimal gap.