Medicare has four parts, and most people need more than one
Medicare is divided into Part A, Part B, Part C, and Part D. Part A covers hospital stays. Part B covers doctor visits and outpatient care. Part C is an alternative way to get Parts A and B through a private insurance company. Part D covers prescription drugs. Most people who sign up for Medicare end up with Part A and Part B, and many add Part D. Part C replaces A and B rather than adding to them.
You do not have to take all four parts. Some people take only Part A. Some take A and B but skip D because they do not take many medications. The combination you choose depends on what care you use and what you can afford to pay out of pocket.
Key Takeaways
- Part A covers hospital inpatient care, skilled nursing facilities, hospice, and some home health services after a hospital stay.
- Part B covers doctor office visits, outpatient surgery, lab tests, imaging, and preventive care like screenings and vaccines.
- Part C is a private insurance alternative that covers everything Part A and B cover, usually with lower premiums but higher out-of-pocket costs at the doctor.
- Part D is prescription drug coverage and is separate from A, B, and C — you can add it to Original Medicare or get it bundled in a Part C plan.
- You choose your coverage during your initial enrollment period or during the annual open enrollment period in the fall.
Part A: Hospital and facility care
Part A covers inpatient hospital stays, meaning you are admitted to the hospital and stay overnight. It pays for your room, meals, nursing care, and most hospital services. It also covers skilled nursing facility care — a facility that provides medical care after a hospital stay, not a regular nursing home. Part A covers up to 100 days in a skilled nursing facility if you meet the requirements.
Part A also covers hospice care if you are diagnosed with a terminal illness, and some home health services if you are homebound and a doctor orders them. Most people do not pay a monthly premium for Part A if they or their spouse paid Medicare taxes for at least 10 years while working. If you did not work long enough, you can buy Part A, but the premium is higher.
Part A does have a deductible and copayments. In 2024, the hospital deductible is $1,632 per benefit period — meaning you pay this amount before Part A starts paying. After that, you pay copayments for each day you stay in the hospital past day 60. These amounts change each year.
Part B: Doctor visits and outpatient care
Part B covers visits to your doctor, whether in an office or a hospital outpatient department. It pays for lab tests, X-rays, CT scans, and other imaging. It covers outpatient surgery, emergency room visits, and ambulance services. Part B also covers preventive care at no cost to you — things like annual wellness visits, cancer screenings, diabetes screenings, and vaccines.
Part B has a monthly premium that most people pay. In 2024, the standard premium is $164.90 per month, but the amount you pay depends on your income — higher earners pay more. You also pay a yearly deductible (in 2024, it is $240) and then 20 percent of the cost of most services after that.
Part B does not cover routine dental care, vision exams, hearing aids, or most physical therapy. It also does not cover prescription drugs — that is Part D. If you want coverage for these services, you need to buy separate insurance or pay out of pocket.
Part C: An alternative to Part A and Part B
Part C, also called Medicare Advantage, is a private insurance plan that covers everything Part A and Part B cover. Instead of getting your Medicare coverage directly from the government, you get it from an insurance company that contracts with Medicare. Most Part C plans also include Part D prescription drug coverage, and many include dental, vision, or hearing coverage that Original Medicare does not offer.
Part C plans usually have lower monthly premiums than Original Medicare plus a separate Part D plan. However, you typically pay more when you see a doctor — a higher copayment or coinsurance. Part C plans also have networks, meaning you usually have to see doctors in the plan's network or pay more. Some plans require you to get a referral before seeing a specialist.
Part C plans vary widely. Some are HMOs with strict networks. Some are PPOs that let you see out-of-network doctors for a higher cost. Some are regional plans available only in certain areas. You can switch to a different Part C plan or back to Original Medicare during the annual open enrollment period in the fall, but not at other times of year.
Part D: Prescription drug coverage
Part D covers prescription medications. If you have Original Medicare (Part A and Part B), you need to add Part D separately through a private insurance company. If you have Part C, most plans include Part D automatically, though some do not — you should check before you sign up.
Part D plans vary in which drugs they cover and how much you pay. Each plan has a formulary — a list of drugs it covers. If your doctor prescribes a drug not on the formulary, you either pay the full cost yourself or ask your doctor to prescribe a different drug that is covered. Part D plans also have different copayments and coinsurance amounts depending on the drug and the plan.
Part D has a coverage gap, sometimes called the "donut hole." Once you and your plan have spent a certain amount on drugs in a year, you enter the gap and pay a higher percentage of the cost until you reach catastrophic coverage. In 2024, the gap starts after $5,850 in total drug costs. This changes each year, and the amount you pay in the gap has been decreasing.
How to choose which parts you need
If you use a lot of prescription medications, you need Part D. If you see doctors regularly, you need Part B. If you want lower monthly premiums and do not mind higher copayments at the doctor, Part C might save you money. If you want more choice in doctors and do not want to deal with a network, Original Medicare (Part A and Part B) with a separate Part D plan might be better.
The best choice depends on your health, your doctors, your medications, and your budget. You can compare plans using the Medicare Plan Finder tool on Medicare.gov. You can also call 1-800-MEDICARE to talk to someone who can answer questions about your specific situation.
You choose your coverage during your initial enrollment period when you first turn 65, or during the annual open enrollment period from October 15 to December 7 each year. If you miss these windows, you may have to wait until the next year to change your coverage, and you may pay a penalty for late enrollment in Part B or Part D.
What to ask your doctor
Before you choose your Medicare coverage, ask your doctor which specialists you see and whether they accept Medicare. Ask which medications you take regularly and whether they are expensive. Ask whether you need any services that Original Medicare does not cover, like dental or vision care. If you are thinking about Part C, ask whether your doctor is in the plan's network.
If you already have Medicare and are thinking about switching, ask your doctor whether they accept the new plan you are considering. Ask your pharmacist which Part D plans cover your medications at the lowest cost. These conversations take a few minutes and can save you hundreds of dollars a year.
Frequently Asked Questions
Do I have to take all four parts of Medicare?
No. Part A and Part B are separate — you can take Part A without Part B, though most people take both. Part C replaces Part A and Part B, so you choose either Original Medicare (A and B) or Part C, not both. Part D is separate and optional, but if you do not take it when you first turn 65, you may pay a penalty later.
What is the difference between Original Medicare and Part C?
Original Medicare is Part A and Part B run by the government. You can see any doctor who accepts Medicare. Part C is a private insurance plan that covers the same services but through an insurance company. Part C usually costs less per month but more per doctor visit, and you have to use doctors in the plan's network.
Can I switch from one part to another after I sign up?
You can switch during the annual open enrollment period from October 15 to December 7 each year. You can also switch if you have a may have access to life event, like moving out of your plan's service area or losing other insurance. Outside these windows, you are locked into your choice until the next open enrollment period.
Will I pay a penalty if I do not take Part D?
If you do not take Part D when you first turn 65 and you do not have other prescription drug coverage, you will pay a penalty when you do sign up. The penalty is about 1 percent of the national average Part D premium for each month you were without coverage. This penalty stays with you for as long as you have Part D.
How do I know which Part D plan covers my medications?
Use the Medicare Plan Finder on Medicare.gov and enter the medications you take. The tool will show you which plans cover each drug and how much you will pay. You can also call your pharmacy and ask which Part D plans they work with, or call 1-800-MEDICARE to speak with someone who can help you compare.