Medicare is four parts, one penalty rule, and a coordination question that shows up on every health-side exam. It's also one of the most-searched insurance topics in America — your clients' parents are on it, and so, eventually, will your clients be. Here's each part in one breath, then the distinctions the exam actually tests.
The four parts
Part A — hospital insurance. Inpatient hospital care, skilled nursing facility (post-acute, limited), hospice, some home health. Premium-free for most people (earned through 40 quarters of Medicare-taxed work); carries per-benefit-period deductibles and coinsurance.
Part B — medical insurance. Doctors, outpatient care, durable medical equipment, preventive services. Everyone pays a monthly premium (income-adjusted), plus an annual deductible and 20% coinsurance after it. This is the part with the enrollment windows and lifetime late-enrollment penalties.
Part C — Medicare Advantage. The private-plan alternative to Original Medicare: an approved private insurer bundles A + B (+ usually D) into an HMO/PPO-style plan, often with extras (vision, dental, fitness). Same entitlement, different delivery — the government pays the plan a fixed amount to provide your coverage.
Part D — prescription drugs. Private plans covering outpatient prescription drugs, added by the same law that created the Advantage system. Voluntary, but the late-enrollment penalty (added to premiums permanently, calculated per full uncovered month) applies once eligibility ends — the trap that makes "voluntary" feel theoretical.
Part C vs. Supplement (Medigap): the confusion to kill
Both stack on Original Medicare, but they're alternatives to each other, not partners:
- Medicare Advantage (Part C) replaces Original Medicare's delivery — network rules, plan costs, one card. You can't add a Medigap plan to an Advantage plan (with narrow transition exceptions).
- Medigap (supplement) fills the gaps of Original Medicare — the Part A/B deductibles and the 20% coinsurance. Sold by private insurers as standardized lettered plans (currently A, B, D, G, K, L, M, N — several letters retired over the years, and the C and F plans closed to people newly eligible for Medicare after 2019), works only with Original Medicare, guaranteed-issue rights tied to specific enrollment windows.
The rule the exam tests: Advantage and Medigap are mutually exclusive. Enroll in one or the other; "Advantage + Medigap stacking" is a wrong answer every time it appears.
Enrollment windows (the penalties live here)
- Initial Enrollment Period (IEP): 7 months around the 65th birthday — 3 before, the month of, 3 after. The clean window with guaranteed issue.
- General Enrollment: January–March annually, with Part B premiums carrying late-enrollment penalties (permanent, percentage-based on years delayed).
- Special Enrollment: employer coverage ends (or employment ends) → 8 months to enroll in Part B penalty-free.
- Annual enrollment (Advantage/Part D changes): October 15 – December 7 yearly.
Medicare vs. Medicaid — one word, different worlds
Medicare is federal, age/disability-based entitlement, unrelated to income. Medicaid (in California, Medi-Cal) is joint federal-state, means-tested — based on income and assets. People can be dual-eligible (both programs, with Medicare primary and Medicaid picking up cost-sharing). The exam's version: a low-income 70-year-old — which program pays first? Medicare (entitlement-based) primary, Medicaid payer of last resort. And in California, the name to know is Medi-Cal — the state-specific set drills it →.
How the exam packages Medicare
Expect coordination questions ("who pays first"), Part-vs-Part definition matching, the Advantage/Medigap exclusivity rule, and penalty-window scenarios ("didn't enroll in Part B at 65, still working with group coverage — penalty?"). No — group coverage preserves Special Enrollment rights. The full scenario range lives in Medical Expense practice →.
Frequently asked questions
Is Medicare Part A free?
For most people, yes — premium-free after 40 quarters of Medicare-qualified employment (or via a spouse's record). Fewer quarters means a buy-in premium. Part B always carries a monthly premium.
Can I have Medicare Advantage and a Medigap plan together?
No — they're mutually exclusive by design. Advantage replaces Original Medicare's delivery; Medigap supplements it. You're choosing one architecture or the other.
What's the difference between Medicare and Medi-Cal?
Medicare is federal entitlement based on age (65+) or disability, regardless of income. Medi-Cal is California's Medicaid program — state-administered, income-based. Dual-eligible individuals get both, with Medicare primary. Name-matching (Medicaid/Medi-Cal) is a standing California exam item.
Does Medicare cover long-term care?
No — Medicare covers skilled care (post-hospital, time-limited), not custodial long-term care. That gap is what LTC insurance and the California Partnership program → exist to fill. Practice the boundary questions: Medical Expense domain →