The complexity of Medicare, which is comprised of 4 major programs, confuses many people: Parts A, B, C, and D. Medicare Part A and Part B are usually called “Original Medicare.” Generally speaking, Part A covers in-patient hospitalization while Part B covers outpatient services and other medical care. Part C denotes the “Medicare Advantage” program where private insurance companies deliver Medicare Part A and Part B benefits to plan enrollees. Part D is the Medicare prescription drug benefit.

Your circumstances dictate when you can enroll or change Part C and Part D plans. For those who already have a Part D plan, the annual enrollment period (AEP) is October 15 through December 7.