Medicare has four separate parts, and most people need more than one

Medicare Part A covers hospital stays, skilled nursing care after a hospital stay, hospice, and home health services. Part B covers doctor visits, outpatient care, and medical equipment. Part D covers prescription drugs. Part C, also called Medicare Advantage, is an alternative to Parts A and B — it bundles hospital and medical coverage into a single private plan, usually with lower out-of-pocket costs but a smaller network of doctors.

Most people turn 65 and enroll in Part A and Part B automatically. Part D is separate and you choose it during a specific window each year. Part C is optional — you can use it instead of A and B, but not alongside them. Understanding what each part pays for and what it does not is the first step to knowing what gaps you might need to fill with other coverage.

Key Takeaways

  • Part A covers hospital and facility care; Part B covers doctor visits and outpatient services; together they are Original Medicare.
  • Part D is prescription drug coverage and must be chosen separately during the annual enrollment period or you may face a penalty later.
  • Part C (Medicare Advantage) bundles A and B coverage into one private plan with different costs and networks, and you cannot have it at the same time as Original Medicare.
  • Original Medicare (A and B) has no network — you can see any doctor who accepts Medicare — but Part C plans usually require you to use in-network providers.

Part A: Hospital and Facility Care

Part A pays for inpatient hospital stays, including room, meals, and standard nursing care. It covers up to 60 days in a hospital per benefit period, with you paying a deductible for the first day and coinsurance after day 60. A benefit period begins when you enter the hospital and ends 60 days after you leave; if you return within that window, it is the same benefit period.

Part A also covers skilled nursing facility care — not regular nursing home care, but care in a facility certified by Medicare after a hospital stay of at least three days. It pays for up to 100 days per benefit period, with you paying coinsurance after day 20. Home health services are covered if you are homebound and a doctor orders them; hospice care is covered if you are terminally ill. Most people do not pay a premium for Part A if they or their spouse paid Medicare taxes for at least 10 years.

Part B: Doctor Visits and Outpatient Services

Part B covers doctor office visits, preventive care like annual wellness exams and screenings, outpatient surgery, emergency room visits, and diagnostic tests like X-rays and blood work. It also covers durable medical equipment — wheelchairs, oxygen, walkers — and mental health services. Part B has an annual deductible, and after you meet it, you typically pay 20 percent coinsurance for most services while Medicare pays 80 percent.

Part B is optional, but if you do not enroll when you first become may be able to access at 65, you will pay a higher premium for each year you delayed. The standard premium changes each year. Part B has no network — any doctor or hospital that accepts Medicare must accept your Part B coverage, so you can see any provider you choose without referrals.

Part C: Medicare Advantage as an Alternative to A and B

Part C, or Medicare Advantage, is a private insurance plan that contracts with Medicare to provide your Part A and Part B coverage. Instead of going to any Medicare-accepting doctor, you use doctors and hospitals in the plan's network. Most Part C plans include Part D prescription drug coverage built in, and many add dental, vision, or hearing coverage that Original Medicare does not offer.

Part C plans often have lower out-of-pocket costs than Original Medicare — some have zero premium — but you pay more if you see an out-of-network doctor, and you may need referrals to see specialists. You cannot have Part C and Original Medicare at the same time; if you switch from one to the other, there are specific windows during the year when you can make the change. Part C plans are offered by private insurers and vary by location, so what is available to you depends on where you live.

Part D: Prescription Drug Coverage

Part D covers prescription medications at pharmacies. It is not automatic — you must choose a Part D plan during the annual enrollment period (October 15 to December 7 each year) or when you first become may be able to access. If you do not enroll and later want coverage, you will pay a penalty added to your premium for as long as you have Part D.

Part D plans are offered by private insurers and vary in which drugs they cover, what you pay at the pharmacy, and which pharmacies you can use. Most plans have a deductible, then you pay a copay or coinsurance until you reach a coverage gap (sometimes called the "donut hole"), where you pay more out of pocket. After you spend enough out of pocket, catastrophic coverage kicks in and you pay a small copay for the rest of the year. If you have Original Medicare (A and B), you choose Part D separately. If you have Part C, the plan usually includes drug coverage.

Original Medicare versus Medicare Advantage: The Main Differences

Original Medicare is Part A and Part B together. You can see any doctor or hospital that accepts Medicare, no referrals needed, and you have the same coverage nationwide. You pay a deductible and coinsurance, and you must choose Part D separately for drugs. Medicare Advantage is Part C — a single private plan that covers A and B services through a network. It usually includes drug coverage and may include dental or vision, but you pay more or nothing at all if you see out-of-network providers.

Original Medicare is more flexible if you travel or move, or if you have a doctor you want to keep. Medicare Advantage often costs less upfront but ties you to a network and may require referrals. The choice depends on your health, your doctors, your budget, and whether you want the simplicity of one plan or the flexibility of Original Medicare. You can switch between them during the annual enrollment period or during the Medicare Advantage open enrollment period in January.

What Medicare Does Not Cover

Medicare does not cover routine dental care, eye exams, glasses, or hearing aids — though some Medicare Advantage plans add these. It does not cover long-term custodial care in a nursing home or assisted living, only skilled nursing care after a hospital stay. It does not cover most routine foot care, acupuncture, or cosmetic surgery. Prescription drugs are not covered under Part A or B; you need Part D or a Part C plan that includes drug coverage.

This is why many people buy a supplemental policy, called Medigap, to cover the deductibles and coinsurance that Original Medicare leaves you responsible for. Others choose Medicare Advantage for the lower upfront costs and added benefits. Understanding what each part covers and what gaps exist helps you decide what additional coverage, if any, makes sense for your situation.

Frequently Asked Questions

Do I have to take all four parts of Medicare?

No. Part A is usually automatic at 65. Part B is optional but recommended; if you delay, you pay a penalty later. Part D is optional but has a penalty if you delay. Part C is optional — you can use it instead of A and B, but not with them. You can have A, B, and D together, or A, B, and C together, or just A alone, depending on your needs and situation.

What happens if I do not sign up for Part D when I turn 65?

You can still sign up later, but you will pay a penalty — a percentage increase to your Part D premium for each month you were without coverage. The penalty stays with you as long as you have Part D. If you have creditable coverage from an employer or union, you may not owe a penalty, so check before you enroll.

Can I switch from Medicare Advantage back to Original Medicare?

Yes, but only during specific windows. You can switch during the annual enrollment period (October 15 to December 7) or during the Medicare Advantage open enrollment period (January 1 to March 31). If you switch to Original Medicare, you will need to choose a Part D plan at the same time if you do not already have one.

If I have Part C, do I still need to choose Part D?

Most Part C plans include prescription drug coverage, so you do not need a separate Part D plan. Check your plan documents to confirm what drugs are covered and at what cost. If your Part C plan does not include drug coverage, you can add a standalone Part D plan.

Does Medicare cover my doctor if I travel out of state?

Original Medicare (A and B) covers you anywhere in the United States as long as the provider accepts Medicare. Medicare Advantage plans usually only cover in-network providers in your plan's service area, so traveling out of state may mean paying out of network or using urgent care instead of your regular doctor.