Most people think they understand Medicare — but a recent eHealth survey reveals a shocking knowledge gap that could cost you thousands of dollars. In this eye-opening conversation, Derrick Duke, CEO of eHealth, breaks down everything you need to know before turning 65, including the permanent 10% late enrollment penalty most people don't discover until it's too late, why skipping Part D prescription drug coverage is a costly mistake, and how Medicare plans change every year making an annual review essential.