Plain-English guide
Medicare, explained
Medicare has four parts, optional supplement insurance and several enrollment windows. Here is how they fit together, so you know what to ask.
- Annual Enrollment
- Oct 15 – Dec 7
- Medicare Advantage OEP
- Jan 1 – Mar 31
- Initial Enrollment
- 7 months around 65
The parts of Medicare
What each part covers
| Part | What it covers | Good to know |
|---|---|---|
| Part A | What it coversHospital insurance: inpatient hospital stays, skilled nursing facility care, hospice and some home health care. | Good to knowMost people don't pay a premium for Part A because they or a spouse paid Medicare taxes while working. |
| Part B | What it coversMedical insurance: doctor visits, outpatient care, preventive services and medical equipment. | Good to knowHas a monthly premium. Together, Parts A and B are called Original Medicare. |
| Part C | What it coversMedicare Advantage: plans from Medicare-approved private companies that include Part A and Part B, and usually Part D. | Good to knowYou still pay your Part B premium. Plans have their own networks, costs and service areas. |
| Part D | What it coversPrescription drug coverage. | Good to knowA standalone plan you add to Original Medicare, or included in many Medicare Advantage plans. |
Medicare Supplement (Medigap)
Medigap is insurance sold by private companies that helps pay some costs Original Medicare doesn't, such as copayments, coinsurance and deductibles. It works only with Original Medicare, not with Medicare Advantage, and it doesn't include drug coverage.
Key periods
When you can enroll or change
Special Enrollment Periods may also apply after events like moving or losing other coverage.
- Initial Enrollment Period7 months around your 65th birthday
- The 3 months before the month you turn 65, your birthday month and the 3 months after.
- Annual Enrollment PeriodOctober 15 – December 7
- Join, switch or drop a Medicare Advantage or Part D plan. Changes start January 1.
- Medicare Advantage Open EnrollmentJanuary 1 – March 31
- If you're in a Medicare Advantage plan, you can switch to another one or return to Original Medicare, once.
ProtecWise is a licensed insurance agency and is not connected with or endorsed by the U.S. government or the federal Medicare program. Medicare information on this page is general in nature and not a complete description of benefits, coverage, or limitations. Medicare Advantage, Medigap, and Part D plans have varying costs, benefits, and service areas. This website does not provide Medicare quotes or enrollment.