Bad information about Medicare gets passed around as true. These four myths cost real seniors real dollars every year — here's what the rules actually say. SHORT ANSWER: Four of the most common Medicare misconceptions can cost you serious money if you get them wrong: (1) that you must enroll at 65 no matter what, (2) that any employer drug coverage protects you from the Part D penalty, (3) that HSA contributions automatically stop at 65, and (4) that COBRA counts as coverage