Difference between Medicare Part A and Part B

Say you are admitted for a covered hospital stay, and then keep paying your 20 percent share on everything that follows it. Part A handled the room. Part B is handling the rest, and there is nothing on top of it capping the total.

What does Medicare Part A cover?

Medicare Part A is hospital insurance, one of the two parts that make up Original Medicare. It helps cover inpatient care in hospitals, care in a skilled nursing facility, hospice care, and home health care. Inpatient care is the anchor: Part A is the part built around a hospital stay.

Inpatient care is the anchor: Part A is the part built around a hospital stay.

The wording on Medicare.gov deserves a second look: Part A helps cover these things. Helps is doing real work in that sentence. Part A paying does not mean Part A paying everything, and the costs that remain are the subject of a later section on this page.

The shape of the list is what separates the parts. Hospitals, skilled nursing facilities, hospice, home health. Stays and programs of care, not office visits.

Medicare.gov's more detailed Part A page adds a hedge worth keeping: it covers some home health care, not all of it. Hold that thought, because home health care is about to appear again.

What does Medicare Part B cover?

Medicare Part B is medical insurance, the second half of Original Medicare. It helps cover services from doctors and other health care providers, outpatient care, home health care, durable medical equipment, and many preventive services, including screenings, vaccines, and yearly wellness visits. Part B is the part for everyday medical care.

Medicare.gov sorts everything Part B does into two buckets. Medically necessary services are services or supplies that meet accepted standards of medical practice to diagnose or treat your condition. Preventive services are care meant to prevent illness, like the flu, or to catch it at an early stage, when treatment is likely to work best.

Preventive care gets special treatment. You pay nothing for most preventive services when the provider accepts assignment, which means the provider takes the Medicare-approved amount as full payment.

Durable medical equipment is the physical kit of recovery and daily life. Medicare.gov's own examples are wheelchairs, walkers, and hospital beds.

What is the difference between Part A and Part B?

The difference between Medicare Part A and Part B is the situation, not the service. Call it the Two Lists: home health care appears on Medicare.gov's list for Part A and on its list for Part B. Part A is organized around inpatient stays. Part B is organized around outpatient and everyday care.

The Two Lists is an observation about Medicare.gov's own summary page, where home health care is the one item sitting on both lists. Both facts are the government's. The naming is ours.

The split is easiest to hold as one line each.

	Part A	Part B
Pays for	Inpatient care, where you are admitted	Doctors, outpatient care and equipment
Most people pay	No premium, if you or a spouse worked enough	A monthly premium
Deductible resets	Each benefit period, so possibly twice a year	Once a calendar year

The bottom row is the one that surprises people. Part A does not run on the calendar the way almost everything else in Medicare does.

That overlap is the clearest evidence that the parts are not sorted by service name. Asking which part covers home health care has no one-word answer, because it depends on the situation in which the care is given.

So the honest way to read the two lists is as descriptions of two situations, a stay and a visit, rather than as two menus of services.

Do you pay a premium for Part A?

Medicare Part A is premium-free for most people who paid Medicare taxes, or whose spouse did, generally for at least 10 years of work. Premium-free means no monthly bill for Part A itself, not free care: Part A keeps a deductible, and it can apply more than once in a year.

That deductible behaves differently from most insurance. It is charged for each hospital benefit period rather than once a year, and Medicare.gov states plainly that you may pay it more than once in a year.

The 10 year figure carries the government's own hedge, generally, and this article keeps the hedge. Work records have edges, and the page that states the rule links to a qualification check rather than promising an answer. People who get Medicare earlier than age 65 skip the question entirely: they do not pay a Part A premium.

Not qualifying is not a dead end. You might be able to buy Part A, with two strings attached. You also have to sign up for Part B to buy Part A. And waiting is expensive: buy it late and the monthly premium may go up 10 percent, paid for twice the number of years you did not sign up.

How much does Part B cost?

Medicare Part B costs a standard monthly premium, and the amount changes from year to year, so the current figure lives on Medicare.gov's costs page. People with higher incomes pay more. The premium is charged every month, even months with no doctor visits, and a yearly deductible sits on top.

After the deductible, the pattern is coinsurance: you usually pay 20 percent of the cost of each covered service or item, as long as the provider accepts assignment. Coinsurance means your share is a percentage of the bill rather than a flat fee.

There is no yearly limit on those out-of-pocket costs in Original Medicare, unless supplemental coverage or a Medicare Advantage Plan adds one.

Signing up late has a price of its own. The Part B late penalty adds an extra 10 percent for each year you could have signed up but did not, for as long as you have Part B. Generally it does not apply if you qualify for a Special Enrollment Period or enroll in a Medicare Savings Program.

Do Part A and Part B work together?

Part A and Part B work together as one system called Original Medicare. Part A handles the hospital side and Part B handles the medical side, and one hospital stay can draw on both. With Original Medicare you can use any doctor or hospital that takes Medicare, anywhere in the United States.

The cleanest illustration is a hospital stay. The stay itself is Part A territory. But most doctor services you receive while you are a hospital inpatient bill under Part B, with the usual 20 percent share of the Medicare-approved amount. One event, two parts, two sets of costs.

Original Medicare also defines what it leaves out. Drug coverage is not included, and adding it means joining a separate Medicare drug plan.

Your share of the costs can be helped too. Medigap is extra insurance you can buy from a private company that helps pay your share of costs in Original Medicare.

What this means for you

Part A and Part B split one program into a hospital half and a medical half, and the split runs by situation, not by service name. Expect both to matter, sometimes inside the same hospital stay. Knowing which half a bill belongs to is how the paperwork starts making sense.

The two parts are also the foundation everything else stands on. Joining a Medicare Advantage Plan requires having Part A and Part B first. Joining a separate drug plan requires at least one of them. Every later choice assumes the two halves are in place.

If the vocabulary is new, start with the two official names. Hospital insurance is Part A. Medical insurance is Part B. The rest of Medicare is built from combinations, and the next two pieces of that vocabulary are Medicare Advantage and Part D.

FAQ

Do I need both Medicare Part A and Part B?

Original Medicare is the combination of the two: Part A for hospital insurance and Part B for medical insurance. Whether you need both enrolled at once depends on your situation, and the rules push the parts together more than people expect.

To buy Part A when you do not qualify for it premium-free, you also have to sign up for Part B. To join a Medicare Advantage Plan, you need both Part A and Part B first.

Some people with employer coverage delay Part B, and that is a real decision with its own rules and deadlines. The honest summary: the program is built as a pair, and the paths that use only one part are the exceptions.

What is Original Medicare?

Original Medicare is the name for Part A and Part B taken together, the federal health insurance program itself. With it you can use any doctor or hospital that takes Medicare, anywhere in the United States.

It does not include drug coverage: you can join a separate Medicare drug plan to add Part D. Your share is usually a 20 percent coinsurance, a fixed slice of each covered bill.

There is no yearly ceiling on that share. A ceiling arrives only if you buy supplemental coverage, called Medigap, or join a Medicare Advantage plan. Original Medicare is the default framework, and every other choice, Medigap, Part D, Medicare Advantage, is defined by how it attaches to it or replaces it.

Does Part A or Part B cover prescription drugs?

Mostly neither. The prescriptions you fill at a pharmacy are the job of Part D, Medicare's drug coverage, which you get through a separate drug plan or through a Medicare Advantage Plan that includes it. Part B's coverage list does include limited outpatient prescription drugs, which is a narrow category rather than everyday medication coverage.

The practical reading: if the question is about the medicines in your cabinet, the answer lives in Part D, not in Part A or Part B. That is why the parts matter when you first sign up. Original Medicare alone leaves prescriptions uncovered until a drug plan is added, and Medicare.gov warns that joining one late can carry a penalty.

What does accepting assignment mean?

Accepting assignment means a doctor or provider agrees to take the Medicare-approved amount as full payment for a covered service. The phrase matters because two of Part B's most important cost rules are tied to it. After you meet the deductible, you usually pay 20 percent of the cost of a covered service as long as the provider accepts assignment.

And you pay nothing for most preventive services, but only when the provider giving them accepts assignment. When a provider does not accept assignment, those two rules no longer promise the same arithmetic. It is worth asking the question directly when you book an appointment: one word in a billing office changes the numbers of the visit.

Is there a limit on what I pay out of pocket?

Not inside Original Medicare itself. Part A and Part B carry no yearly limit on what you pay out of pocket. Two things add one. A Medicare Supplement Insurance policy, called Medigap, or a Medicare Advantage plan, which sets its own out-of-pocket limit.

That absence surprises people. A 20 percent coinsurance sounds small until it is 20 percent of something large, with no ceiling above it. The two exceptions the rule itself names, supplemental coverage and Medicare Advantage, are the two common ways people add a ceiling. That structural difference is worth knowing before the first large bill arrives, not after.

What happens if I sign up for Part B late?

A late enrollment penalty can attach to Part B, and it is built to sting. The penalty is an extra 10 percent of the premium for each full year you could have signed up but did not, and it is paid for as long as you have Part B.

It is not a one-time fee. For most people it is a lifetime surcharge. Generally you will not pay it if you qualify for a Special Enrollment Period, for example when you had other coverage similar in value to Medicare through an employer, or if you enroll in a Medicare Savings Program.

The percentage is fixed by the rule, but the premium it multiplies can change each year, so the penalty follows it.