Medicare Part A vs. Part B: What Each One Covers

The Core Difference: Hospital vs. Doctor

Medicare Part A covers hospital stays, skilled nursing care after a hospital stay, hospice, and home health services. Medicare Part B covers doctor visits, outpatient care, medical equipment, and preventive services. Part A is automatic when you turn 65 if you have worked and paid Medicare taxes. Part B is optional but most people enroll because the cost is low and the coverage is broad.

The simplest way to remember the split: Part A pays the facility (the hospital building, the nursing home), and Part B pays the provider (your doctor, your therapist, your lab). If you are admitted to a hospital, Part A covers the bed and meals. If a doctor orders tests while you are there, Part B covers the doctor's work and the test itself.

You do not have to choose between them. Most people have both. But they work differently, cost differently, and cover different things, so understanding each one matters when you get a bill or need to decide whether to enroll in Part B.

Key Takeaways

• Part A covers inpatient hospital stays, skilled nursing facilities, hospice, and home health; Part B covers doctor visits, outpatient services, and preventive care.
• Part A is automatic at 65 if you have paid Medicare taxes; Part B requires you to enroll and costs roughly $165 per month in 2024, though the amount changes yearly.
• Part A has a deductible per hospital stay (not per day), and you pay coinsurance after 60 days; Part B has an annual deductible and then you pay 20 percent of approved costs.
• If you delay enrolling in Part B without a valid reason, you may pay a penalty for the rest of your life, so enroll during your initial enrollment window or a special enrollment period.
• Neither part covers dental, vision, hearing aids, or long-term custodial care, which is why many people also buy Medigap or Medicare Advantage.

What Medicare Part A Covers

Part A covers a hospital stay from the moment you are admitted as an inpatient until you are discharged. It pays for your room, meals, nursing care, medications given in the hospital, and basic medical supplies. It does not cover a doctor's individual fees — that is Part B's job — but it does cover the facility itself.

Part A also covers up to 100 days in a skilled nursing facility (a nursing home or rehabilitation center) if you are admitted within 30 days of a hospital stay of at least three days. The first 20 days are fully covered. Days 21 through 100 require you to pay a daily coinsurance amount, which changes yearly. After 100 days, you pay everything yourself.

Home health services are covered by Part A if a doctor orders them, you are homebound, and you need skilled care (nursing, physical therapy, speech therapy). Part A also covers hospice care for people with a terminal illness, including medications and equipment related to the terminal condition.

What Medicare Part B Covers

Part B covers visits to your doctor, whether in an office, clinic, or hospital outpatient department. It covers preventive services like annual wellness visits, cancer screenings, vaccines, and blood pressure checks — usually with no cost to you beyond your monthly premium. It covers lab tests, imaging (X-rays, ultrasounds, CT scans), and procedures done in an outpatient setting.

Part B also covers durable medical equipment — wheelchairs, walkers, oxygen tanks, diabetic supplies — if a doctor prescribes it. It covers mental health services, including therapy and psychiatry. It covers ambulance services if medically necessary. Physical therapy, occupational therapy, and speech therapy are covered when ordered by a doctor.

Part B does not cover routine dental work, vision exams, eyeglasses, hearing aids, or routine foot care. It does not cover most prescription drugs — that is Part D's job. It does not cover long-term custodial care (help with bathing, dressing, meals) unless it is part of skilled nursing or home health ordered by a doctor.

How the Costs Work: Deductibles and Coinsurance

Part A has a deductible per hospital stay, not per day. In 2024, that deductible is $1,632 for each benefit period (a benefit period begins when you enter the hospital and ends 60 days after you leave). If you are hospitalized twice in the same year, you pay the deductible twice. After you meet the deductible, Part A covers 100 percent of your hospital stay for days 1 through 60. Days 61 through 90 require you to pay a daily coinsurance amount. Days 91 and beyond are covered only if you use your "lifetime reserve days," which are limited and non-renewable.

Part B has an annual deductible (in 2024, $240) that you pay once per calendar year. After you meet it, you pay 20 percent of the Medicare-approved amount for most services, and Medicare pays 80 percent. For preventive services with no deductible, you pay nothing. The amounts change every January.

Both parts have limits. Part A limits skilled nursing to 100 days per benefit period. Part B limits physical therapy and occupational therapy to a combined 60 visits per year (though this can change). If you exceed these limits, you pay the full cost yourself unless you have Medigap or Medicare Advantage coverage.

Enrollment: When You Must Sign Up

Part A is automatic. When you turn 65, if you have paid Medicare taxes for at least 10 years (40 quarters), you are enrolled in Part A whether you ask for it or not. You do not have to do anything. If you are not yet receiving Social Security, you will receive a Medicare card in the mail about three months before your 65th birthday.

Part B is optional, but your enrollment window matters. Your initial enrollment period is the three months before the month you turn 65, the month you turn 65, and the three months after. If you enroll during this window, your coverage starts the month you turn 65 (or the month after, depending on when you enroll). If you miss this window and do not have a valid reason — such as current employer coverage or a special enrollment period — you pay a late enrollment penalty for the rest of your life. The penalty is 10 percent of the Part B premium for each year you delayed, compounded.

You can enroll in Part B during the general enrollment period (January 1 through March 31 each year), but coverage does not start until July 1, and you still owe the penalty unless you have a valid reason for the delay.

Part A and Part B Do Not Cover Everything

Neither part covers dental work, routine vision care, or hearing aids. Neither covers long-term custodial care — help with activities of daily living like bathing, dressing, and meals — unless it is part of a skilled nursing stay or home health ordered by a doctor. Neither covers most prescription drugs (Part D does). Neither covers routine foot care, acupuncture, or most alternative therapies.

This is why many people buy Medigap (supplemental insurance) or switch to Medicare Advantage (Part C), which is an alternative to Parts A and B offered by private insurers. Medigap fills gaps in Part A and Part B coverage. Medicare Advantage replaces Part A and Part B but often includes prescription drug coverage and dental or vision benefits. The choice depends on your health, your budget, and what coverage matters most to you.

Frequently Asked Questions

Do I have to enroll in Part B?

Part B is optional, but if you do not enroll when you are first may be able to access and do not have a valid reason (such as employer coverage), you will pay a penalty for the rest of your life. Most people enroll because the monthly premium is low and the coverage is broad. If you are still working and have employer coverage, you may be able to delay without penalty.

What happens if I go to the emergency room?

If you are admitted to the hospital as an inpatient, Part A covers the stay. If you are treated in the emergency room and sent home without admission, Part B covers the emergency room visit and any tests or procedures. The distinction is whether you are admitted as an inpatient or treated as an outpatient.

Can I have both Part A and Part B?

Yes. Most people have both. Part A is automatic, and Part B is optional but recommended. Together they cover a broad range of hospital and doctor services. You can also have both and buy Medigap on top, or switch to Medicare Advantage instead of having both.

What if my doctor is not in the Medicare network?

Part B covers any doctor who accepts Medicare, whether in-network or out-of-network. However, if a doctor does not accept Medicare assignment, they can charge you more than the Medicare-approved amount. Always ask your doctor whether they accept Medicare and whether they accept assignment before your visit.

Do Part A and Part B cover prescription drugs?

No. Prescription drug coverage is Part D, which is separate and optional. You enroll in Part D during your initial enrollment period or during the annual open enrollment period (October 15 through December 7). If you do not enroll when first may be able to access and go without coverage, you pay a penalty when you eventually enroll.