The Basic Difference
Medicare Part A covers hospital care — inpatient hospital stays, skilled nursing facilities, hospice, and some home health services. Medicare Part B covers doctor visits, outpatient care, lab tests, imaging, and medical equipment like wheelchairs or oxygen. Part A is automatic when you turn 65 if you have worked and paid Medicare taxes. Part B requires you to sign up, and most people pay a monthly premium for it.
Most people have both parts together, often called "Original Medicare." They work as a pair: Part A covers what happens when you are admitted to a hospital, and Part B covers the doctors and tests involved in your care.
Key Takeaways
- Part A covers hospital stays, nursing home care, and hospice; Part B covers doctor visits, outpatient procedures, and preventive care.
- Part A is automatic at 65 if you have worked and paid Medicare taxes; Part B requires you to sign up during your enrollment window.
- Part A has a deductible per hospital stay; Part B has a yearly deductible and then a 20 percent coinsurance for most services.
- If you do not sign up for Part B when you are first may be able to access, you may pay a permanent penalty on your premium later.
- Original Medicare (Part A and Part B together) does not cover prescription drugs, dental, vision, or hearing aids.
What Part A Covers
Part A pays for inpatient hospital stays — meaning you are admitted and stay overnight. It covers the room, meals, nursing care, and most hospital services. The coverage lasts up to 60 days per benefit period without you paying anything after you meet the deductible. Days 61 through 90 require a daily coinsurance payment from you. After 90 days, you can use "lifetime reserve days" (60 total across your life) at a higher daily cost.
Part A also covers skilled nursing facility care if you need rehabilitation after a hospital stay — but only if you were admitted to the hospital first and only for up to 100 days per benefit period. It covers hospice care for people with a terminal illness, and it covers some home health services when ordered by a doctor, such as nursing visits or physical therapy at home.
Part A does not cover custodial care (help with bathing or dressing), long-term care in a nursing home if you do not need skilled nursing, or private duty nursing.
What Part B Covers
Part B covers doctor visits — whether in an office, urgent care clinic, or hospital outpatient department. It pays for preventive services like annual wellness visits, cancer screenings, and vaccinations. It covers diagnostic tests: blood work, X-rays, CT scans, and ultrasounds. It pays for physical therapy, occupational therapy, and speech therapy when ordered by a doctor.
Part B also covers durable medical equipment — wheelchairs, walkers, oxygen equipment, diabetic supplies, and similar items prescribed by a doctor. It covers ambulance services, mental health counseling, and dialysis. It pays for most outpatient surgery and procedures done in a hospital or surgery center.
Part B does not cover routine dental work, eyeglasses or contact lenses, hearing aids, or most prescription drugs (though it does cover some drugs given in a doctor's office or hospital). It does not cover cosmetic surgery or most weight-loss surgery.
How Costs Work for Each Part
Part A has a deductible per benefit period — a benefit period starts when you enter the hospital and ends 60 days after you leave. In 2024, that deductible is $1,632, but this amount changes each year. Once you meet the deductible, Part A covers the full cost of days 1 through 60 of a hospital stay. Days 61 through 90 require you to pay a daily coinsurance (in 2024, $408 per day). After that, you pay even more or use your lifetime reserve days.
Part B has a yearly deductible (in 2024, $240) and then requires you to pay 20 percent of the cost of most services after that. Your doctor's office or the lab will bill Medicare first, and Medicare pays 80 percent; you owe the remaining 20 percent. Part B also has a monthly premium that most people pay, which varies based on your income.
Neither Part A nor Part B has an out-of-pocket maximum — meaning there is no limit to how much you could pay in a year. This is one reason many people buy supplemental insurance (Medigap) or choose Medicare Advantage instead.
Enrollment and Timing
Part A is automatic. When you turn 65, if you have worked at least 10 years and paid Medicare taxes, Part A enrollment happens without you doing anything. You will receive your Medicare card in the mail about three months before your 65th birthday.
Part B is not automatic — you must sign up. Your initial enrollment window is the three months before your 65th birthday, your birth month, and the three months after. If you sign up during this window, Part B coverage starts the month you turn 65. If you miss this window and do not have other health insurance (like employer coverage), you will pay a permanent 10 percent penalty on your Part B premium for as long as you have Medicare.
If you are still working and covered by your employer's health plan at 65, you can delay Part B without penalty. You have eight months after your employer coverage ends to sign up without penalty. Keep documentation of your employer coverage dates in case Medicare asks.
What Is Not Covered by Part A or Part B
Original Medicare does not cover prescription drugs. You need to sign up for Part D (prescription drug coverage) separately, usually through a private insurance company contracted with Medicare. If you do not sign up when you are first may be able to access and later want it, you may pay a permanent penalty.
Neither part covers dental work, eyeglasses, contact lenses, or hearing aids. Some Medicare Advantage plans include these benefits, but Original Medicare does not. Long-term care in a nursing home (custodial care) is not covered. Neither part covers routine foot care, weight-loss surgery, or cosmetic procedures.
If you need coverage for these services, you can buy a Medigap policy (supplemental insurance) to fill some gaps, or you can switch to a Medicare Advantage plan, which is an alternative to Original Medicare offered by private insurers.
Part A and Part B Working Together
Here is how they work in a real situation: You go to the emergency room and are admitted to the hospital. Part A covers your hospital stay. While you are there, a cardiologist visits you — Part B covers that doctor visit. You have blood work and an EKG — Part B covers those tests. After three days, you are discharged to a skilled nursing facility for rehabilitation. Part A covers the nursing facility stay (up to 100 days). A physical therapist works with you there — Part B covers that therapy.
You meet Part A's deductible with the hospital stay. You also meet Part B's yearly deductible with the doctor visit and tests. After that, you pay 20 percent coinsurance for Part B services (like the physical therapy) for the rest of the year. Part A continues to cover the nursing facility at no additional cost to you (within the 100-day limit).
Frequently Asked Questions
Do I have to take Part B if I have Part A?
No, but it is strongly recommended. Part A alone covers only hospital and nursing facility care. Without Part B, you would pay the full cost of doctor visits, lab tests, and outpatient care. Most people who delay Part B end up regretting it because of the permanent penalty.
Can I use Part A and Part B at the same time?
Yes. They are designed to work together. Part A covers the hospital or facility, and Part B covers the doctors and tests. You will likely use both if you have a serious illness or injury.
What happens if I turn 65 and do not sign up for Part B?
If you do not have other health insurance and miss your enrollment window, you will have to wait until the next General Enrollment Period (January 1 to March 31) to sign up. When you do, your coverage will not start until July 1, and you will pay a 10 percent penalty on your premium for life.
Does Part A or Part B cover my medications?
Neither one covers most prescription drugs. You need Part D (prescription drug coverage) for that. Part B covers only drugs given to you in a doctor's office or hospital, like chemotherapy or certain injections.
What is the difference between Original Medicare and Medicare Advantage?
Original Medicare is Part A and Part B together, run by the federal government. Medicare Advantage is an alternative offered by private insurance companies that includes Part A and Part B coverage plus usually Part D and sometimes dental or vision. Medicare Advantage often has lower premiums but requires you to use doctors in their network.