What Is Medicare? Parts A, B, C and D Explained

Who qualifies for Medicare

Medicare is federal health insurance for people 65 and older. Some younger people qualify too, including people who have received Social Security disability benefits for 24 months and people with end-stage renal disease (permanent kidney failure) or ALS.

Most people earn Medicare by working and paying Medicare taxes for at least 10 years (40 quarters). If you didn't, you may still qualify through your spouse's work record.

Original Medicare: Parts A and B

Parts A and B are run by the federal government and together are called Original Medicare. They're the foundation for all other Medicare coverage: you need both to buy a Medicare Supplement plan or join a Medicare Advantage plan.

What Part A covers

Part A is hospital insurance. It helps pay for:

• Inpatient hospital stays, including a semi-private room, meals, nursing care and supplies
• Short-term care in a skilled nursing facility after a hospital stay of at least 3 days
• Hospice care
• Some home health care

Part A does not pay for long-term custodial care, such as help with bathing and dressing in a nursing home or an assisted living facility. That surprises many people, so it's worth planning for separately.

What Part B covers

Part B is medical insurance. It covers care from doctors and other providers, mostly outside of a hospital stay:

• Doctor and specialist visits
• Outpatient procedures and surgery
• Lab tests, x-rays and other imaging
• Preventive care, including a "Welcome to Medicare" visit in your first 12 months and a yearly wellness visit
• Medical equipment such as walkers, wheelchairs and home oxygen
• Ambulance services
• Outpatient mental health care

Part C: Medicare Advantage

Medicare Advantage plans are offered by private insurance companies approved by Medicare. They provide your Part A and Part B benefits instead of Original Medicare, must cover everything Original Medicare covers, and most include drug coverage too. Many add extras like dental, vision, hearing or fitness benefits.

Most Medicare Advantage plans use a network of doctors and hospitals, and every plan has a yearly limit on what you pay out of pocket for covered care.

Part D: prescription drug coverage

Part D plans are sold by private insurance companies and help pay for prescriptions. You can add a stand-alone Part D plan to Original Medicare, or get drug coverage built into a Medicare Advantage plan. Our Part D guide covers the details.

What you pay with Original Medicare

In 2026, the Part A deductible is $1,736 for each hospital benefit period, and the Part B deductible is $283 for the year. After you meet the Part B deductible, you generally pay 20% of the Medicare-approved amount for covered services.

Original Medicare has no yearly limit on what you can owe. If you needed $100,000 of Part B treatment in a year, your 20% share would be $20,000. That's why most people pair Original Medicare with a Medicare Supplement plan, or choose a Medicare Advantage plan with an out-of-pocket limit. Our Medicare Costs guide breaks down all the numbers.

Thrive 65 tip: don't miss your Part B window

If you don't sign up for Part B when you're first eligible, and you don't have coverage through your own or your spouse's current job, you'll pay a late penalty. It adds 10% to your Part B premium for each full 12 months you went without Part B, and it usually lasts for as long as you have Part B.

How to get Original Medicare

You sign up for Parts A and B through Social Security, not through an insurance company. If you already receive Social Security benefits at least 4 months before you turn 65, you'll be enrolled automatically, and your Medicare card will arrive about 3 months before your birthday month. Otherwise, you'll need to apply. Our Applying for Medicare guide shows you how.