Part A and Part B are the two main pieces of Original Medicare

Part A covers hospital care — inpatient stays, skilled nursing facilities, hospice, and some home health services. Part B covers doctor visits, outpatient care, lab tests, imaging, and medical equipment. Together they form what Medicare calls Original Medicare, and most people who turn 65 get both automatically. They are not the same thing, they do not cover the same services, and you can have one without the other — though that is rare and usually a mistake.

The distinction matters because your costs, your deductibles, and what you owe out of pocket are completely different under each part. A hospital stay costs you nothing under Part A after you meet the deductible, but a doctor visit under Part B means you pay 20 percent of the approved amount. Understanding which part covers what prevents you from showing up at a hospital expecting Part B to pay, or calling your doctor expecting Part A to cover it.

Key Takeaways

  • Part A covers hospital inpatient stays, skilled nursing care after hospitalization, hospice, and some home health services; Part B covers doctor visits, outpatient procedures, lab work, and medical equipment.
  • Part A has a deductible per hospital stay; Part B has a yearly deductible and then you pay 20 percent of approved charges for most services.
  • Most people get both parts automatically at 65, but you can refuse Part B if you have other coverage — refusing Part A is almost never the right choice.
  • Neither part covers dental, vision, hearing aids, or long-term custodial care in a nursing home, which is why many people add Part D, Part C, or supplemental insurance.

What Part A covers and what it costs

Part A pays for inpatient hospital stays, meaning you are admitted to the hospital and stay overnight. It covers the room, meals, nursing care, and most tests and procedures done while you are admitted. If you need skilled nursing care after leaving the hospital — physical therapy, wound care, or other medical services that require a nurse — Part A covers up to 100 days in a skilled nursing facility, though you pay a daily copay after day 20.

Part A also covers hospice care if you are diagnosed with a terminal illness, and it covers some home health services when ordered by your doctor — wound care, physical therapy, or nursing visits at home. It does not cover custodial care, meaning help with bathing, dressing, or meals when no medical care is involved.

The cost structure is a deductible per hospital stay, not per year. In 2024, that deductible is $1,632 for each benefit period (the amount changes yearly). After you meet it, you pay nothing for the first 60 days of a hospital stay. Days 61 through 90 cost you a daily copay. Beyond 90 days, you can use your lifetime reserve days, which are limited. Most people never hit these limits, but the point is that Part A is designed to protect you from catastrophic hospital bills, not to cover small outpatient costs.

What Part B covers and what it costs

Part B covers doctor visits, whether in an office or a hospital outpatient department. It covers preventive care — annual wellness visits, cancer screenings, vaccines — at no cost to you. It covers lab tests, X-rays, CT scans, and other diagnostic imaging. It covers outpatient surgery, emergency room visits, and urgent care. It covers durable medical equipment like wheelchairs, walkers, oxygen, and CPAP machines.

Part B does not cover routine dental work, vision exams, eyeglasses, or hearing aids. It does not cover most prescription drugs (that is Part D). It does not cover physical therapy or occupational therapy unless it is part of a covered service like rehabilitation after a hospital stay.

Part B has a yearly deductible — $240 in 2024 — and after you meet it, you typically pay 20 percent of what Medicare approves for the service. Your doctor or provider bills Medicare, Medicare pays 80 percent of the approved amount, and you owe the remaining 20 percent. If your provider does not accept Medicare assignment, you could owe more. The monthly premium for Part B varies based on your income; most people pay around $175 per month in 2024, but higher earners pay more.

The difference between Original Medicare and Medicare Advantage

Part A and Part B together make up Original Medicare, which is run directly by the federal government. You can use any doctor or hospital that accepts Medicare, and there are no networks. You pay your deductibles and coinsurance, and you are responsible for the full bill if you see an out-of-network provider.

Medicare Advantage, also called Part C, is an alternative to Original Medicare. Instead of Part A and Part B, you enroll in a private insurance plan — usually an HMO or PPO — that must cover everything Part A and Part B cover, but often with lower out-of-pocket costs and included prescription drug coverage. The tradeoff is that you have a network, you may need referrals, and you usually cannot use out-of-network providers except in emergencies. Some people choose Advantage because the monthly premium is lower or zero; others stay with Original Medicare because they want the freedom to see any doctor.

You cannot have both Original Medicare and Medicare Advantage at the same time. You choose one or the other when you turn 65 or during the annual open enrollment period in the fall.

What neither Part A nor Part B covers

Both parts exclude dental care, routine vision exams, eyeglasses, and hearing aids. If you need these services, you have to pay out of pocket or buy a separate dental or vision plan. Some Medicare Advantage plans include dental or vision coverage, but Original Medicare does not.

Neither part covers long-term custodial care in a nursing home — the kind of care where you need help with daily living but not medical care. If you need to live in a nursing home for years, Medicare will not pay for it. Medicaid may, depending on your income and assets, but that is a different program entirely.

Neither part covers routine foot care, most acupuncture, or cosmetic surgery. Neither covers most prescription drugs — that is Part D, a separate enrollment. Neither covers travel outside the United States, except in rare cases involving Canada or Mexico near the border.

When you turn 65 and how enrollment works

When you turn 65, you become may be able to access for Medicare. If you are already receiving Social Security, Medicare enrolls you automatically in Part A and Part B, and your Part B premium is deducted from your Social Security check. If you are not yet receiving Social Security, you need to sign up yourself at Medicare.gov or at your local Social Security office.

You have a seven-month window called your Initial Enrollment Period — three months before the month you turn 65, the month you turn 65, and three months after. If you miss this window and do not have other health coverage, you pay a permanent penalty on your Part B premium for as long as you have Medicare. The penalty is 10 percent for each year you could have had Part B but did not enroll.

If you are still working and have health insurance through your employer, you can delay Part B without penalty as long as your employer coverage is active. You must enroll in Part B within eight months of losing that coverage, or you face the same permanent penalty. Part A has no such penalty, so most people enroll in Part A even if they delay Part B.

How to decide between Original Medicare and Medicare Advantage

The choice between Original Medicare (Part A and Part B) and Medicare Advantage (Part C) depends on your health, your doctors, and your budget. Original Medicare gives you the freedom to see any doctor or hospital, but you pay deductibles and coinsurance for each service. Medicare Advantage usually has lower or zero monthly premiums and includes prescription drug coverage, but you are locked into a network and may need referrals.

If you have a chronic condition and see the same doctors regularly, check whether those doctors are in the Medicare Advantage plan's network before you enroll. If you travel frequently or live part of the year in another state, Original Medicare is usually simpler because you do not have to worry about networks. If you take many prescription drugs, Medicare Advantage often costs less because the plan includes Part D coverage.

You can switch between Original Medicare and Medicare Advantage once per year during the annual open enrollment period, which runs from October 15 to December 7. If you switch to Medicare Advantage, you automatically drop Original Medicare. If you switch back to Original Medicare, you can enroll in a Medigap supplemental plan to cover some of the deductibles and coinsurance, though you cannot do both at the same time.

Frequently Asked Questions

Do I have to take Part B when I turn 65?

No, but if you delay Part B and do not have other health coverage, you pay a permanent 10 percent penalty on your premium for every year you could have had it. If you are still working and have employer health insurance, you can delay Part B without penalty as long as you enroll within eight months of losing that coverage.

What happens if I see a doctor who does not accept Medicare?

Under Original Medicare, you can see any doctor, but if they do not accept Medicare assignment, you may owe more than the standard 20 percent coinsurance. Under Medicare Advantage, you usually cannot see out-of-network doctors except in emergencies, and you will owe more if you do.

Can I have Part A without Part B?

Yes, though it is uncommon. You might do this if you have other health coverage that includes outpatient care but not hospital coverage. However, most people enroll in both because Part A has no monthly premium and protects against catastrophic hospital bills.

Does Part B cover my prescription drugs?

No. Prescription drug coverage is Part D, a separate enrollment. You can add Part D to Original Medicare, or it is usually included in Medicare Advantage plans. If you do not enroll in Part D when you first become may be able to access, you may pay a permanent penalty.

What is the difference between a deductible and coinsurance?

A deductible is the amount you pay before Medicare starts paying. Coinsurance is the percentage you pay after the deductible is met. Under Part B, you pay a $240 yearly deductible, then 20 percent of approved charges. Under Part A, you pay a deductible per hospital stay, then nothing for the first 60 days.