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By Vivek Sharma·TECHTuesday, October 27, 2026· 5 min read

Medicare Parts A, B, C and D, Explained Simply

Four letters, two paths. A plain-English map of what each part of Medicare covers, what it costs in 2026, and how Original Medicare differs from Medicare Advantage.

Medicare is the US federal health insurance program for people aged 65 and over. It also covers some younger people: those who have received Social Security disability benefits for 24 months, and people with ALS or end-stage kidney disease. It is not the same as Medicaid, which is run by the states and based on income. Medicare is split into four parts with letters, and the letters cause most of the confusion. The simplest way to hold it in your head: Parts A and B are the core coverage, Part D adds prescription drugs, and Part C is a different way of getting A, B and usually D from a private insurer.

Original Medicare is Part A (hospital) plus Part B (doctors), with Part D (drugs) added separately. Part C, Medicare Advantage, bundles A, B and usually D into one private plan.Original MedicarePart Ahospital,nursing, hospiceusually $0 / moPart Bdoctors,outpatient, tests$202.90 / mo+Part Dprescriptiondrugsprivate planorPart CMedicareAdvantageone private plan= A + B+ usually D+ extrasTwo ways to get the same core coverageOriginal Medicare: A + B, then add D (and Medigap) yourselfMedicare Advantage: Part C bundles A + B (+ D) in one plan

Part A is hospital insurance. It covers inpatient hospital stays, care in a skilled nursing facility after a hospital stay, hospice care and some home health care. Most people pay no monthly premium for it, because they or their spouse paid Medicare taxes while working for at least 40 quarters, about 10 years. People with fewer quarters can still buy Part A. 'Premium-free' does not mean free to use, though: in 2026 a hospital stay comes with a deductible of $1,736 per benefit period before Part A starts paying.

Ten years of work with four quarters each gives 40 credits of Medicare taxes, which makes Part A premium-free.a quarter of work paying Medicare tax = 1 creditQ1Q2Q3Q412345678910years of workPart A:$0 a month10 years × 4 quarters = 40 credits40 credits → premium-free Part AFewer credits? You can still buy Part A.

Part B is medical insurance. It covers doctor visits, outpatient care, lab tests, durable medical equipment such as wheelchairs, some home health care, and preventive services like screenings and flu shots. Unlike Part A, everyone pays a monthly premium. In 2026 the standard premium is $202.90 a month, and people with higher incomes pay more. There is also a yearly deductible of $283, after which you typically pay 20% of the Medicare-approved cost of each service.

Part D covers prescription drugs you take at home, plus certain vaccines. It is sold by private insurers approved by Medicare, either as a standalone plan that sits alongside Parts A and B, or built into a Medicare Advantage plan. Plans charge their own monthly premium and cover different lists of drugs. Since 2025 there is a yearly cap on what you pay out of pocket for covered drugs. In 2026 it is $2,100, not counting premiums.

Part C, better known as Medicare Advantage, is not extra coverage on top of A and B. It replaces them. A private insurer approved by Medicare provides your hospital and medical coverage, and most plans also include Part D drug coverage plus extras that Original Medicare does not cover, such as dental, vision and hearing. You still pay your Part B premium, plus whatever the plan charges (some plans charge $0). In return, you usually have to use the plan's network of doctors and hospitals, through an HMO or PPO.

That leaves two paths. Original Medicare (Parts A and B) comes straight from the federal government and lets you see any doctor or hospital in the country that accepts Medicare. But it has no yearly limit on your 20% share, so most people add a standalone Part D plan and a Medigap supplement policy to cover the gaps. Medicare Advantage bundles everything into one private plan with a network and a yearly out-of-pocket maximum, which in 2026 can be no higher than $9,250 for in-network care. You cannot buy Medigap if you are on Medicare Advantage. Neither path is better for everyone; it is a trade between freedom to choose doctors and a predictable, capped cost.

At 65 you choose between Original Medicare (government, any doctor, no yearly cap, add Part D and Medigap) and Medicare Advantage (private insurer, network, yearly cap up to $9,250, usually includes drugs).Original Medicare• run by the federal government• any doctor that takes Medicare• no yearly cap on your 20% share• add Part D + MedigapMedicare Advantage• run by a private insurer• a network of doctors (HMO / PPO)• yearly cap: up to $9,250 (2026)• usually adds drugs + extraswhich path?Pick when you first sign up; you can switch each year, Oct 15 – Dec 7

The difference matters well beyond the patient. For a clinic, knowing which path a patient is on decides who gets the bill. A patient on Original Medicare is billed to Medicare itself using their Medicare number. A patient on Medicare Advantage is billed to the private plan, with a different member ID, its own rules and often prior authorisation. Bill the wrong one and the claim is denied, the same kind of mismatch that makes Medicaid managed care so hard to verify.

Timing matters too. Your first chance to sign up is a seven-month window around your 65th birthday: the three months before, the month itself and the three months after. Signing up late for Part B or Part D can mean a penalty added to your premium for as long as you have coverage. After that, the Medicare open enrollment period runs from October 15 to December 7 each year, when you can switch between Original Medicare and Medicare Advantage or change plans. Official details are on medicare.gov and ssa.gov.