En español | When you stop working, you don’t have to enroll in Medicare Part B if you don’t want to, and your FEHB plan can’t require you to. Your benefits under the plan you choose are the same whether you sign up for Part B or not. If you want to have both types of coverage (in which case, Medicare would become your primary insurance), or if you want to drop the FEHB plan and rely wholly on Medicare, those are choices you’re free to make.
Still, the Office of Personnel Management, which administers the FEHB program, suggests some points to consider:
Note that prescription drug coverage provided by FEHBP plans is creditable, so you don’t need Part D drug coverage unless Part D’s Extra Help program for low-income people would be helpful to you.
For more information, see the Office of Personnel Management’s guidance in its publication “The Federal Employees Health Benefits Program and Medicare” (PDF).