Medicare basics: Parts A, B, C, and D explained
Published May 23, 2026
Medicare is built from parts, and knowing what each does helps you avoid gaps and late penalties.
Part A covers hospital stays and is premium-free for most people. Part B covers doctor visits and outpatient care and has a monthly premium. Together they are "Original Medicare."
Part C (Medicare Advantage) bundles A and B (often with D) through a private plan, sometimes with extra benefits and network rules. Part D covers prescription drugs.
Enrollment timing matters: missing your initial window can mean lifelong late-enrollment penalties for Part B and Part D. Mark your eligibility dates early.
Frequently asked questions
＋ When should I enroll in Medicare?
Most people enroll during the seven-month window around their 65th birthday. Delaying without other qualifying coverage can trigger lifelong penalties.
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