When Can I Enroll In Medigap? 
Most people will enroll in a Medigap -LRB- Medicare supplement -RRB- plan when they first become eligible for Medicare . Most carriers require you to have Medicare Part A and Part B in effect before they will issue a Medigap plan . Even if you buy a Medigap plan that does not require you to have Medicare Part B , your supplement plan will pay AS IF you had Part B. 