Published 2026-09-12 · Last updated 2026-09-12.
Part A — hospital insurance
Part A is hospital insurance. It covers inpatient hospital stays, skilled nursing facility care after a qualifying hospital stay, hospice care, and some home health care. Most people pay no monthly premium for Part A because they or a spouse paid Medicare taxes while working for long enough, in general terms; people who do not qualify on that basis can usually buy it.
Part A's cost-sharing works per benefit period rather than per calendar year, which surprises many new beneficiaries. Read your plan documents for how a benefit period works before you assume a single annual deductible covers every hospital stay in a year.
Part B — medical insurance
Part B is also where income-related adjustments appear: higher incomes can mean a higher Part B premium. The cost calculator page lets you enter any such amount yourself, rather than storing a rate, so your total reflects your situation rather than a national average.
Part C — Medicare Advantage
Part C, or Medicare Advantage, is a private-plan alternative that bundles Parts A and B and usually Part D into a single plan, often with extras such as dental, vision or hearing. It replaces Original Medicare rather than adding to it: when you join an Advantage plan, that plan provides your Medicare benefits under its own network and rules.
You still pay your Part B premium, plus any plan premium, copays and coinsurance the plan sets. The extras attract many buyers, but the network and prior-authorisation rules decide whether those extras are usable for you. Check both before you choose, using the plan comparison page.
Part D — prescription drug coverage
Part D is prescription drug coverage, sold by private plans either standalone alongside Original Medicare or bundled inside most Advantage plans. Premiums, deductibles and copays vary by plan, and each plan has a formulary — a list of covered medicines and their tiers — that decides what your medicines actually cost on that plan.
Formulary position matters more than headline premium for anyone on regular medicines. A plan with a low premium that places your medicine on a high tier can cost more overall than a higher-premium plan that covers it cheaply. Check every regular medicine against the formulary, and re-check annually, because formularies change.
Original vs Advantage — recap
Original Medicare plus Medigap plus Part D gives broad access and predictable cost-sharing across separate pieces, at the cost of managing several premiums and policies. Medicare Advantage gives a single bundled plan with extras, at the cost of working inside a network and plan rules. Neither is universally better; the comparison page and the cost calculator turn that abstract choice into a concrete one for your doctors, medicines and budget.
If any part is still fuzzy after this page, re-read that part's section above and then open the enrollment page to see when each choice must be made. Understanding the parts first, and the windows second, is the order that prevents the most common Medicare mistakes.
ILLUSTRATIVE EXAMPLE
ILLUSTRATIVE EXAMPLE (not a policy fact): Grace, a fictional new beneficiary, lists her regular hospital, doctor and medicine needs, then maps each need to a Part in the example: a hospital stay to Part A, doctor visits to Part B, a bundled plan alternative to Part C, and her prescriptions to Part D. Seeing the map on one page stops her from buying a drug plan she does not need on top of an Advantage plan that already includes one. No premium or coverage figure in this example is asserted as a fact.