You do need to know that you cannot have a Medicare Supplement plan and a Medicare Advantage plan at the same time. You also must know that Medicare Supplement (GAP) plans do not have Part D prescription drug coverage. This means that you WILL NEED to purchase a stand-alone Part D plan. This is to protect you from having to pay the late enrollment penalty which will follow you through your lifetime on Medicare coverages. For those that qualify for VA, Tricare or other QUALIFIED Sources for their drug coverages considered by Medicare to be as good as Medicare , will not have to get part D coverage and they will not be penalized.