Your ZIP code decides which Medicare plans you can actually get.

Part A is hospital insurance. It helps cover inpatient hospital stays, care in a skilled nursing facility after a qualifying hospital stay, hospice, and some home health care. Most people don't pay a monthly premium for Part A if they or their spouse worked and paid Medicare taxes long enough.

Part B is medical insurance. It helps cover doctor visits, outpatient care, preventive services, and medical supplies. Part B has a monthly premium.

Mr. Zip explains: Part B

Medicare Advantage plans are offered by private insurance companies approved by Medicare. They bundle Part A and Part B, and most include drug coverage. Many plans add extra benefits such as dental, vision, and hearing. Benefits, networks, and costs vary by plan and by where you live.

Mr. Zip explains: Medicare Advantage

Part D is prescription drug coverage, offered by private plans approved by Medicare. You can get it as a stand-alone drug plan with Original Medicare, or as part of a Medicare Advantage plan. If you go without creditable drug coverage for a long time after you first become eligible, you may pay a late enrollment penalty for as long as you have Part D.

A Medicare Supplement plan works alongside Original Medicare (Parts A and B) to help pay costs Medicare doesn't cover, such as deductibles, coinsurance, and copays. Medigap plans don't include drug coverage, so many people pair one with a Part D plan.

Medicare Advantage and Part D plans are sold by service area. The plans, networks, and costs available to you depend on where you live, so comparing plans for your exact ZIP code shows you what you can actually get.

Mr. Zip explains: why your ZIP code matters

Your Initial Enrollment Period is 7 months: the 3 months before the month you turn 65, your birthday month, and the 3 months after. Each year, the Annual Enrollment Period runs October 15 to December 7, with changes starting January 1. If you have Medicare Advantage, you can also make one change from January 1 to March 31. Certain life events, like moving or losing employer coverage, can give you a Special Enrollment Period.