Medicare Part A covers hospital stays, and Part B covers doctor visits and outpatient care

Medicare Part A is hospital insurance. It pays for inpatient hospital stays, skilled nursing facility care after a hospital stay, hospice care, and some home health services. You do not pay a monthly premium for Part A if you or your spouse paid Medicare taxes for at least 10 years while working.

Medicare Part B is medical insurance. It pays for doctor visits, outpatient services, lab tests, X-rays, ambulance transport, durable medical equipment (like wheelchairs or oxygen), and some preventive care. Part B requires a monthly premium, which changes each year based on your income.

Together, Part A and Part B form Original Medicare. They work side by side: Part A covers the facility or hospital setting, and Part B covers the doctors and services within it. You can use both at the same time, or you can choose a Medicare Advantage plan (Part C) instead, which bundles Part A and Part B coverage into one plan run by a private insurance company.

Key Takeaways

  • Part A covers hospital stays and facility care with no monthly premium for most people, while Part B covers doctor visits and outpatient services and requires a monthly premium.
  • You pay a deductible for Part A hospital stays and a deductible plus 20 percent coinsurance for most Part B services after you meet the deductible.
  • Part A hospital coverage is limited: it covers up to 60 days fully, then charges you per day for days 61–90, and has a lifetime reserve of 60 additional days.
  • You must sign up for Part B during your initial enrollment window or pay a late enrollment penalty for as long as you have Medicare.
  • Original Medicare (Part A and B) works with any doctor or hospital that accepts Medicare, unlike Medicare Advantage plans, which use networks.

What Part A actually covers and what it costs

Part A covers an inpatient hospital stay from the moment you are admitted as an inpatient until you are discharged. It pays for your room, meals, nursing care, medications, and hospital services. It does not cover a hospital stay if you are admitted as an outpatient for observation, even if you stay overnight — that is a Part B service.

For a hospital stay in 2024, you pay a deductible of $1,632 for the first 60 days. Days 61 through 90 cost you $408 per day. If you need to stay longer, Medicare has a lifetime reserve of 60 additional days, and you pay $816 per day for those. After your lifetime reserve is exhausted, you pay all costs. This deductible and these per-day amounts change each year.

Part A also covers up to 100 days in a skilled nursing facility (a facility that provides medical care and rehabilitation, not a long-term care home) if you were hospitalized for at least three days first. You pay nothing for days 1–20, then $204 per day for days 21–100 in 2024. After 100 days, you pay everything yourself.

Part A covers hospice care for people with a terminal illness, and it covers some home health services if you are homebound and a doctor orders them. Home health is covered at no cost to you if the home health agency is Medicare-approved.

What Part B covers and what it costs

Part B covers doctor office visits, whether your doctor is in a hospital, clinic, or private practice. It covers preventive care like annual wellness visits, cancer screenings, and vaccinations. It covers lab work, imaging (X-rays, ultrasounds, CT scans), physical therapy, mental health counseling, and ambulance transport to a hospital.

Part B also covers durable medical equipment — items like wheelchairs, walkers, oxygen equipment, and diabetic supplies — if a doctor orders them and the supplier is Medicare-approved. It covers some outpatient surgery and procedures done in a hospital outpatient department or ambulatory surgery center.

For Part B, you pay a monthly premium. In 2024, the standard premium is $164.90 per month, but it is higher if your income is above a certain level. You also pay an annual deductible of $240 in 2024. After you meet the deductible, you typically pay 20 percent of the cost of the service, and Medicare pays 80 percent. Some preventive services have no cost to you after you meet the deductible.

Part B does not cover routine dental care, eyeglasses, hearing aids, or long-term custodial care in a nursing home. It does not cover most prescription drugs — that is Part D.

How Part A and Part B work together in a hospital stay

When you are admitted to a hospital as an inpatient, Part A pays for the hospital facility. The doctors who treat you bill Part B. So you might pay Part A's deductible for the hospital stay itself, and then you might also owe Part B coinsurance for the doctor who admitted you or performed surgery.

If you receive outpatient services at a hospital — such as lab work, imaging, or observation — Part B covers those services, not Part A. You pay Part B's deductible and coinsurance, not Part A's hospital deductible.

After you leave the hospital, if you go to a skilled nursing facility, Part A covers the facility costs (after your three-day hospital stay requirement is met). Doctors at the facility bill Part B for their services. You pay Part A's per-day cost for the facility and Part B coinsurance for the doctors.

When you must sign up for Part A and Part B

You become may be able to access for Medicare at age 65. Your Initial Enrollment Period is the seven-month window that starts three months before the month you turn 65, includes the month you turn 65, and ends three months after. If you sign up during this window, your coverage starts the month you turn 65 (or the first day of the month you turn 65 if you were born on the first day of a month).

Part A is automatic for most people: if you are already receiving Social Security benefits when you turn 65, Medicare Part A enrollment happens without you doing anything. If you are not yet receiving Social Security, you must contact Social Security to sign up for Part A.

Part B is not automatic. You must sign up during your Initial Enrollment Period. If you do not sign up when you are first may be able to access, you pay a late enrollment penalty of 10 percent of the Part B premium for each full year you delayed, and you pay this penalty for as long as you have Part B. The only exception is if you or your spouse were still working and had health insurance through an employer; in that case, you may have a Special Enrollment Period after you or your spouse stops working or loses that coverage.

How Original Medicare differs from Medicare Advantage

With Original Medicare (Part A and Part B), you can see any doctor or go to any hospital in the United States that accepts Medicare. There are no networks, no referrals required, and no prior authorization for most services. You have freedom to choose your providers.

Medicare Advantage (Part C) is an alternative to Original Medicare. It is run by a private insurance company and must cover everything Part A and Part B cover, but it does so through a network. You usually pay a lower or zero monthly premium, but you must use doctors and hospitals in the plan's network (except in emergencies). Many Medicare Advantage plans include Part D drug coverage and dental or vision benefits that Original Medicare does not.

If you choose Original Medicare, you can add Part D (prescription drug coverage) through a separate plan, and you can add a Medigap policy (supplemental insurance) to help pay your deductibles and coinsurance. If you choose Medicare Advantage, you cannot use Medigap.

What you still pay out of pocket with Part A and Part B

Original Medicare covers a lot, but it does not cover everything. You are responsible for deductibles, coinsurance, and copayments. You also pay 100 percent of costs for services Medicare does not cover, such as dental care, routine eye exams, hearing aids, and most prescription drugs (unless you have Part D).

Many people buy a Medigap policy to help cover the gaps. Medigap is supplemental insurance sold by private companies. It pays some or all of your deductibles, coinsurance, and copayments. There are ten standardized Medigap plans (labeled A through N), and each covers a different combination of costs. Medigap premiums vary by plan and by insurance company.

Some people with low income and limited resources may be may be able to access for Medicaid, which can help pay Medicare premiums, deductibles, and coinsurance. Medicaid is a joint federal and state program, so may be able to access and benefits vary by state.

Frequently Asked Questions

Do I have to take Part B if I have Part A?

No. Part A and Part B are separate. You can have Part A without Part B, though most people enroll in both. If you delay Part B and do not have a may have access to reason (like employer coverage), you will pay a late enrollment penalty for the rest of your life.

What happens if I go to the emergency room?

If you are admitted to the hospital as an inpatient from the emergency room, Part A covers the hospital stay. If you are treated in the emergency room and sent home, Part B covers the emergency room visit as an outpatient service. You pay Part B's deductible and coinsurance, not Part A's hospital deductible.

Can I switch from Original Medicare to Medicare Advantage or back?

Yes, during the Annual Enrollment Period (October 15 to December 7 each year), you can switch between Original Medicare and Medicare Advantage, or between different Medicare Advantage plans. Changes take effect January 1.

Does Part B cover my doctor's office visit if I have not met my deductible?

No. You must pay the full cost of the visit until you meet the $240 annual deductible. After you meet it, you pay 20 percent coinsurance and Medicare pays 80 percent. Some preventive services are covered at no cost even before you meet the deductible.

What if my doctor does not accept Medicare?

You can still see that doctor, but Medicare will not pay, and you will owe the full cost. Some doctors accept Medicare but are "non-participating," meaning they may charge you more than Medicare's approved amount. Ask your doctor's office whether they accept Medicare and at what rate before your visit.