Medicare is one of the most critical elements of health care for senior citizens in this country. It's also one of the most misunderstood. A number of myths about Medicare have proliferated, costing countless enrollees both time and money. Here are six myths you might be swayed by and the reality about them:

Myth #1: You must be retired to apply for Medicare.

Reality: You can sign up for Medicare at age 65 regardless of whether you're still working or are already retired. And even though many people lump together Medicare and Social Security, the full retirement age (FRA) for receiving Social Security retiree benefits—currently 66 for most people but gradually rising to 67—has nothing to do with Medicare eligibility. But you can be penalized for applying late for Medicare, so sign up as soon as you reach age 65.