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Medicare Basics: Parts A, B, C and D

Learn what Medicare Parts A, B, C and D cover, and how Original Medicare and Medicare Advantage differ.

Medicare is the federal health insurance program. Most people first get it around age 65. It has four parts, named with letters. This guide explains each part in plain words.

Part A: Hospital insurance

Part A helps pay for care when you are admitted to a hospital. It also covers:

  • A stay in a skilled nursing facility
  • Hospice care
  • Some home health care

Most people do not pay a monthly premium for Part A. That is the case if you or your spouse worked and paid Medicare taxes for at least 10 years.

Part B: Medical insurance

Part B helps pay for care outside the hospital. This includes:

  • Visits with doctors and other health care providers
  • Outpatient care
  • Home health care
  • Medical equipment you use at home over time (called durable medical equipment)
  • Some preventive services, like screenings and some shots

Most people pay a monthly premium for Part B. The amount depends on your income and changes every year. Medicare.gov has this year's numbers.

Part C: Medicare Advantage

Part C is better known as Medicare Advantage. It is another way to get your Part A and Part B coverage. Private companies approved by the federal government run these plans.

A Medicare Advantage Plan bundles Part A, Part B and usually Part D into one plan. Many plans also offer extras, like some vision, hearing or dental care. Medicare Advantage plans must cover all the medically necessary services that Original Medicare covers.

Part D: Prescription drug coverage

Part D helps pay for prescription medicines. Private companies approved by the federal government run these plans. You can get Part D as a separate drug plan, or as part of a Medicare Advantage Plan that includes drug coverage.

Original Medicare or Medicare Advantage?

When you have Medicare, you choose one of two main paths.

Original Medicare is Part A and Part B. With it:

  • You can see any doctor or hospital in the U.S. that accepts Medicare.
  • You usually do not need a referral to see a specialist.
  • For most Part B services, you generally pay 20% of the cost after you meet the yearly deductible.
  • There is no yearly limit on what you pay out of pocket.
  • You can add a separate Part D drug plan.
  • You can buy a Medicare Supplement Insurance policy (called Medigap) from a private company to help pay costs like coinsurance and deductibles.

Medicare Advantage replaces Original Medicare with one private plan. With it:

  • You generally must use doctors and hospitals in the plan's network for care that is not an emergency.
  • You may need a referral to see a specialist.
  • You may need the plan's approval before some services, called prior authorization.
  • Costs vary by plan, but each plan has a yearly limit on what you pay out of pocket for covered services.
  • Most plans include drug coverage.
  • You cannot buy a Medigap policy to help with your costs.

Original Medicare does not cover some things, such as routine physicals, eye exams and most dental care. Some Medicare Advantage plans offer extra benefits for these.

Getting help choosing

There is no one right answer for everyone. Think about the doctors you want to keep, the medicines you take, and whether you travel. You can compare plans on Medicare.gov or call 1-800-MEDICARE (1-800-633-4227).

This guide is general information, not medical advice. Talk with your doctor about your own care.

Have a question about this? Willow can explain in plain words, in English or Spanish.

Last reviewed 2026-10-21. Checked against these sources:

  1. Parts of Medicare (Social Security Administration)
  2. Compare Original Medicare & Medicare Advantage (Medicare.gov)
  3. Get Medigap Basics (Medicare.gov)

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