I would be very surprised if your employer's Health Service Account Group Insurance plan didn't also require that you be enrolled in Medicare Part A.I could be wrong, but I encourage you to to speak with your benefits coordinator at work to find out. There may be a comparable plan at work that coordinates with Medicare.I am not sure, but I would think that your company health plan could coordinate with Medicare much like a Medigap policy (a Medicare supplement insurance).When the plans are coordinated, typically Medicare will pay first (primary) and your insurance will pay second (secondary). Medicare is billed first and pays for services it covers without regard to what the employer insurance covers. Once Medicare has processed a claim, the employer-based insurance will process it and pay for any services it covers. You might also wish to speak with a Medicare Supplemental insurance provider about additional options: https://www.newretirement.com/Services/Medicare_Supplemental_Insurance_Advice.aspx