Medicare Part A vs. Part B: What’s the Difference?
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Medicare Part A and Part B are the two parts of Original Medicare. Although they work together, they cover different types of health care services and can have different premiums, deductibles and cost-sharing.
Quick answer: Medicare Part A is primarily hospital insurance and helps cover inpatient hospital care, skilled nursing facility care when Medicare requirements are met, hospice care and certain home health care. Medicare Part B is medical insurance and helps cover doctors, outpatient care, preventive services, durable medical equipment and other medically necessary services.
For a broader overview of Medicare coverage, costs, plan options and enrollment, see our complete guide to Medicare in California.
What Is the Difference Between Medicare Part A and Part B?
The easiest way to understand the difference is to think of Part A primarily as hospital insurance and Part B primarily as medical insurance.
- Medicare Part A: Primarily covers inpatient and hospital-related care.
- Medicare Part B: Primarily covers doctors, outpatient care and other medical services.
Together, Medicare Part A and Part B make up Original Medicare.
What Does Medicare Part A Cover?
Medicare Part A helps cover certain types of inpatient and facility-based care.
Part A generally helps cover:
- Inpatient hospital care
- Skilled nursing facility care when Medicare requirements are met
- Hospice care
- Certain home health care
Part A does not mean that every service you receive while at a hospital is automatically covered under Part A. Whether Part A or Part B applies can depend on the type of service and whether you are formally admitted as an inpatient.
What Does Medicare Part B Cover?
Medicare Part B helps cover medically necessary services and many types of outpatient health care.
Part B generally helps cover:
- Doctors and other health care providers
- Outpatient hospital services
- Many preventive services
- Durable medical equipment
- Ambulance services when Medicare requirements are met
- Certain home health services
- Some drugs administered in a doctor's office or other outpatient setting
Part B can cover services you receive in a hospital when you are treated as an outpatient rather than formally admitted as an inpatient.
Part A vs. Part B at a Glance
| Medicare Part A | Medicare Part B |
|---|---|
| Hospital Insurance | Medical Insurance |
| Inpatient hospital care | Doctor services |
| Skilled nursing facility care when requirements are met | Outpatient care |
| Hospice care | Preventive services |
| Certain home health care | Durable medical equipment and other covered medical services |
Is Medicare Part A Free?
Many people qualify for premium-free Medicare Part A because they or their spouse paid Medicare taxes for a sufficient period while working.
However, premium-free Part A does not mean all Part A services are free.
Depending on the care you receive, Part A can have deductibles and coinsurance. People who do not qualify for premium-free Part A may be able to purchase Part A and pay a monthly premium.
Do You Pay a Premium for Medicare Part B?
Most people with Medicare Part B pay a monthly premium.
The standard Part B premium can change each year. Some beneficiaries pay a higher premium based on income.
Part B also generally has an annual deductible, and cost-sharing can apply to covered services after the deductible is met.
Because Medicare premiums and deductibles can change from year to year, current amounts should be confirmed through Medicare.gov.
Does Original Medicare Pay 100% of Your Medical Bills?
No. Original Medicare does not generally pay 100% of every covered health care expense.
Part A and Part B can include deductibles, coinsurance and other out-of-pocket costs.
For many Part B services, after the Part B deductible is met, Original Medicare generally pays 80% of the Medicare-approved amount and the beneficiary generally pays 20% when the provider accepts assignment. Different rules can apply depending on the service and provider.
Original Medicare also does not have an annual out-of-pocket maximum for Part A and Part B services.
What Is the Medicare Part B 20% Coinsurance?
For many services covered by Medicare Part B, Medicare generally pays 80% of the Medicare-approved amount after the applicable Part B deductible, and you are generally responsible for the remaining 20%.
For example, if a covered service had a Medicare-approved amount of $100 after the deductible was satisfied, Medicare would generally pay $80 and your 20% coinsurance would be $20.
If the Medicare-approved amount were higher, the 20% portion would generally increase as well.
This example is simplified and actual costs depend on the service, provider and Medicare rules that apply.
What Is Original Medicare?
Original Medicare is the federal Medicare program consisting of:
- Medicare Part A
- Medicare Part B
With Original Medicare, you can generally use any doctor or hospital in the United States that accepts Medicare.
Original Medicare does not include most outpatient prescription drug coverage. People who want prescription drug coverage can generally enroll in a separate Medicare Part D plan.
Some people with Original Medicare also purchase Medicare Supplement Insurance, commonly called Medigap, to help pay certain out-of-pocket costs.
For an overview of all four parts, see New to Medicare: A Beginner’s Guide to Medicare Parts A, B, C and D.
Do You Need Both Medicare Part A and Part B?
Whether and when you should enroll in Part A and Part B depends on your individual circumstances.
Many people enroll in both when they first become eligible for Medicare. However, some people who continue working and have qualifying employer group health coverage may be able to delay Part B without a late-enrollment penalty.
The rules can depend on the type of health coverage you have and whether it is based on current employment.
See Working Past 65: Do You Need to Sign Up for Medicare? if you expect to have employer coverage after becoming eligible for Medicare.
When Do You Enroll in Part A and Part B?
For most people becoming eligible for Medicare at age 65, the Initial Enrollment Period lasts seven months.
It generally begins three months before the month you turn 65, includes your birthday month and continues for three months afterward.
Some people are automatically enrolled, while others need to sign up themselves.
People with qualifying coverage based on current employment may have different enrollment options.
See our complete guide to Medicare enrollment and when to sign up.
Does Part A Cover Doctor Visits in the Hospital?
Not necessarily.
Receiving care inside a hospital does not automatically mean every service is covered under Part A.
Doctors and other professional services can be covered under Part B even while you are receiving hospital care.
Your inpatient or outpatient status can also affect which part of Medicare covers a service and what you may owe.
Does Part B Cover Hospital Care?
Part B can cover certain services you receive at a hospital, particularly outpatient services and professional services such as physician care.
Part A generally covers qualifying inpatient hospital care, while Part B can apply to outpatient hospital services.
This is one reason the distinction between Part A and Part B is based on the type and status of the care rather than simply the building where you receive treatment.
Does Part A or Part B Cover Prescription Drugs?
Part A and Part B can cover certain medications in specific circumstances, but neither provides the same type of outpatient prescription drug coverage as Medicare Part D.
Part A may cover drugs provided as part of covered inpatient treatment. Part B covers certain drugs administered by a doctor or other health care provider and certain other medications that meet Medicare's Part B coverage requirements.
For most outpatient prescription drug coverage, Medicare beneficiaries generally look to Medicare Part D.
Learn more in our guide to Medicare Part D and prescription drug coverage.
What Happens After You Have Part A and Part B?
Once you have Medicare Part A and Part B, you can receive your Medicare benefits through Original Medicare or, if eligible, choose a Medicare Advantage plan.
Medicare Advantage, also known as Part C, is another way to receive your Medicare Part A and Part B benefits through a Medicare-approved private insurance company.
The two approaches can differ in provider access, costs, prescription drug coverage, additional benefits and plan rules.
See Original Medicare vs. Medicare Advantage for a detailed explanation.
Frequently Asked Questions
Is Medicare Part A hospital insurance?
Yes. Medicare Part A is commonly called Hospital Insurance and primarily helps cover qualifying inpatient hospital care and certain other facility-based services.
Is Medicare Part B medical insurance?
Yes. Medicare Part B is commonly called Medical Insurance and helps cover doctors, outpatient care, preventive services, durable medical equipment and other covered medical services.
Are Part A and Part B together called Original Medicare?
Yes. Medicare Part A and Part B together make up Original Medicare.
Is Medicare Part B free?
No. Most people enrolled in Medicare Part B pay a monthly premium. The amount can change each year, and some people pay more based on income.
Does Medicare Part A cover outpatient doctor visits?
Routine outpatient doctor services are generally covered through Medicare Part B rather than Part A.
Does Original Medicare have an out-of-pocket maximum?
Original Medicare does not have an annual limit on what you pay out of pocket for covered Part A and Part B services.
Is Medicare Part C the same as Part A and Part B?
No. Medicare Part C is Medicare Advantage. Medicare Advantage is an alternative way to receive your Part A and Part B benefits through a Medicare-approved private insurance company.
This article is for general educational and informational purposes. Medicare coverage, eligibility, costs and enrollment rules can vary based on individual circumstances and may change over time. For official Medicare information, visit Medicare.gov or call 1-800-MEDICARE.