Medicare Advantage plans are 'privatized' Medicare plans that have fixed networks, doctors and hospitals. Your plan may or may not allow you to go out of the network. If you are able to go out of network, you will pay more money out-of-pocket for your care. With 'original’ Medicare, you do not have a network. You are able to go to any provider in the United States who accepts Medicare. Your Medicare Supplement or Medigap plan will pay the provider secondary to Medicare according to the plan you have.

Yes and No. Yes, you can join a Medicare Advantage plan when you have a Medicare Supplement, at least in theory. But no, you cannot use both a Medicare Supplement and a Medicare Advantage plan together.

Yes. The Centers for Medicare and Medicaid Services (CMS) provides a Special Enrollment Period (SEP) for people who left their Medicare Supplement (Medigap plan) -- joined a Medicare Advantage plan for the first time -- and within the first 12 months these people wish to leave the new Medicare Advantage plan and return to their original Medicare Supplement.

Like other Medicare beneficiaries, if you are enrolled in a Medicare Supplement or Medigap policy, you will need to join a separate stand-alone Medicare Part D plan (PDP) if you wish to have prescription drug coverage.