In order to carry Federal Employees Health Benefits program coverage into retirement, you need to have been covered by the program for the five years leading to retirement. You are not required to have been an enrollee continuously, but you must have been continuously covered by an FEHB enrollment. This includes:
Coverage under Medicare does not count in determining continuous coverage.
Service as a non-appropriated fund employee does not count in determining continuous coverage since it is not federal service and not subject to FEHB coverage.
Breaks in service are not counted as interruptions when the five years of service requirement is determined, as long as you reenroll within 60 days after your return to federal service.
You are considered to have been continuously enrolled when you are allowed to make a late election because your employing office determined that you weren’t able to timely enroll for reasons beyond your control.