Medicare has four parts and two paths, and the terminology is designed to confuse. Part A (hospital) and Part B (medical) are Original Medicare. Part C (Medicare Advantage) is a private-insurer bundle that replaces Original Medicare and usually folds in Part D (drug coverage). The decision that matters most is the path: Original Medicare + a Medigap supplement, or Medicare Advantage.
Medicare Advantage vs Original Medicare: The Real Trade-off
Medicare Advantage plans frequently advertise $0 monthly premiums and extras Original Medicare does not cover — dental, vision, hearing, gym memberships. In exchange, you accept a network (HMO/PPO), referrals and prior authorizations, and an annual out-of-pocket maximum that in 2026 can reach the mid-$8,000s in-network and higher out-of-network. Original Medicare has no network (any provider that accepts Medicare) but no out-of-pocket cap on its own — which is why most Original Medicare enrollees add a Medigap policy.
The honest framing: Medicare Advantage tends to cost less when you are healthy and use little care, and can cost more — in both dollars and hassle — in a year with a major illness, because that is when networks, prior authorization and the out-of-pocket maximum bite. Original Medicare + Medigap costs more in predictable monthly premiums but caps your risk and gives you provider freedom. Neither is universally "better."
Part D and the End of the Coverage Gap
Drug coverage changed materially. The old "donut hole" coverage gap is gone, and there is now a hard annual cap on what you pay out-of-pocket for covered Part D drugs — a genuinely important protection for anyone on expensive medications. When comparing plans, the single most important step is entering your actual prescriptions into the plan finder: two plans with identical premiums can differ by thousands of dollars a year depending on which drugs are on their formulary and at what tier.
The mistake that costs the most
The biggest avoidable error is choosing a plan on premium alone. A $0-premium Advantage plan whose network excludes your doctor, or whose formulary puts your drug on a high tier, can cost far more than a plan with a modest premium. Always check three things against the specific plan: is your doctor in-network, is your hospital in-network, and are your exact drugs covered and at what tier.
The Enrollment Windows You Cannot Miss
Timing is rigid. Your Initial Enrollment Period runs the seven months around your 65th birthday. The Annual Enrollment Period (Oct 15–Dec 7) is when anyone can switch between Advantage and Original Medicare or change drug plans for the following year. There is also a Medicare Advantage Open Enrollment Period (Jan 1–Mar 31) for people already in an Advantage plan to switch once. Miss your initial window without qualifying coverage and you can face lifelong Part B and Part D late-enrollment penalties.
One under-appreciated trap: Medigap. When you first enroll in Part B at 65 you have a guaranteed-issue right to buy any Medigap policy regardless of health. If you start in Medicare Advantage and later try to switch to Original Medicare + Medigap, insurers can medically underwrite you — and decline. That asymmetry is a real reason to think carefully at 65 rather than defaulting to the plan with the flashiest extras.
How to Actually Compare Plans
Build the comparison around your life, not the brochure: list your doctors and hospitals, your exact medications, and how much care you realistically expect. Then compare plans on total expected annual cost (premiums + expected out-of-pocket for your drugs and visits), network fit, and the out-of-pocket maximum — not on premium or advertised extras. The plans that win on a spreadsheet are rarely the ones with the biggest TV budgets.
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