What Is Medicare?
Medicare is a federal health insurance program primarily for people aged 65 and older, as well as certain younger individuals with qualifying disabilities or conditions like End-Stage Renal Disease (ESRD). It is administered by the Centers for Medicare & Medicaid Services (CMS) and funded through payroll taxes, premiums, and general federal revenue.
Medicare is divided into distinct parts, each covering different aspects of healthcare.
Medicare Part A: Hospital Insurance
Part A covers inpatient care and related services. Most people who have paid Medicare taxes for at least 10 years (40 quarters) qualify for premium-free Part A.
Part A covers:
- Inpatient hospital stays
- Skilled nursing facility care (following a qualifying hospital stay)
- Hospice care
- Some home health services
Part A has a per-benefit-period deductible for hospitalizations, not an annual deductible.
Medicare Part B: Medical Insurance
Part B covers outpatient medical services and is optional — but most people who are eligible for Medicare enroll in it. Part B requires a monthly premium (which can vary based on income).
Part B covers:
- Doctor visits and specialist consultations
- Preventive services (many at no cost)
- Outpatient procedures and surgeries
- Durable medical equipment (wheelchairs, walkers, etc.)
- Mental health services
- Some home health services
Medicare Part C: Medicare Advantage
Part C, also called Medicare Advantage, is an alternative way to receive your Medicare benefits through a private insurer approved by Medicare. These plans must cover everything Parts A and B cover, and many include extra benefits such as:
- Prescription drug coverage (Part D)
- Dental, vision, and hearing care
- Fitness program memberships
Medicare Advantage plans operate like HMOs or PPOs and often have network restrictions. You must continue paying your Part B premium even while enrolled in Part C.
Medicare Part D: Prescription Drug Coverage
Part D is optional prescription drug coverage available through private insurers. If you have Original Medicare (Parts A and B) and want drug coverage, you add a standalone Part D plan. Medicare Advantage plans often bundle Part D coverage.
Key Part D concepts:
- Formulary: Each plan has a list of covered drugs organized in cost tiers
- Late enrollment penalty: If you don't enroll when first eligible and don't have other creditable drug coverage, you may pay a permanent premium surcharge
- Coverage gap (historically "donut hole"): Largely closed by legislation, but cost-sharing rules still change at different spending thresholds
Original Medicare vs. Medicare Advantage: A Quick Comparison
| Feature | Original Medicare (A + B) | Medicare Advantage (Part C) |
|---|---|---|
| Provider choice | Any Medicare-accepting provider | Usually network-based |
| Drug coverage | Requires separate Part D | Often included |
| Extra benefits | Limited | Often includes dental/vision |
| Out-of-pocket cap | No cap (Medigap helps) | Annual cap required |
When to Enroll in Medicare
Your Initial Enrollment Period (IEP) is a 7-month window: the 3 months before your 65th birthday month, your birthday month, and the 3 months after. Enrolling during the first 3 months ensures no coverage delays. Missing your IEP without creditable coverage can result in permanent late enrollment penalties for Parts B and D.