Do I need to buy a Medigap policy?
Medigap policies help pay health care costs only if you have the Original Medicare Plan, sometimes called Medicare “fee-for-service.” Whether you need or want to buy a Medigap policy is your decision. You do not need to buy a Medigap policy if you are in a Medicare Advantage Plan (which is often an HMO or PPO), and it may be illegal to sell you a Medigap policy if they know you are in a Medicare Advantage health plan.