The four parts of Medicare
What are the four parts of Medicare?
Medicare is a federal health insurance program for people 65 and older, or under 65 with certain disabilities or end-stage renal disease. Medicare has four parts that cover different health services.
Short Answer
The four parts of Medicare are Part A, Part B, Part C, and Part D.
- Part A covers inpatient/hospital coverage.
- Part B covers outpatient/medical coverage.
- Part C covers Part A, Part B, and sometimes Part D prescription drug costs combined into one plan.
- Part D provides prescription drug coverage.
Original Medicare Parts A and B provide important health care coverage but don’t cover everything. That’s why most people choose additional Medicare coverage, Medicare Advantage Plans, or Supplement plans to help fill these gaps.
Medicare Coverage by Part
| Medicare part | What it covers | Who provides it | Notes |
|---|---|---|---|
| Part A (hospital insurance) | Inpatient hospital stays, skilled nursing facility care, hospice care, and some home health services | Federal government | Most people don’t pay a premium if they or their spouse worked for 10 years and paid Medicare taxes |
| Part B (medical insurance) | Doctor visits, outpatient care, preventive services, medical equipment, lab tests, and home health care services | Federal government | Monthly premium required |
| Part C (Medicare Advantage) | All Part A and Part B services, often with extra benefits like dental, vision, hearing, and prescription drug coverage | Private insurance companies approved by Medicare | May have a monthly premium and usually uses provider networks for care |
| Part D (prescription drug coverage) | Prescription medications | Private insurance companies approved by Medicare | Can be standalone or included in some Medicare Advantage plans |
Medicare Parts explained (Parts A, B, C, D)
It is important to understand the parts of Medicare to help choose the best plan option to meet your health and financial needs. Each part covers different things like hospital stays, doctor visits, prescription drugs, and extra benefits. When you understand what each part covers and how they work together, you can compare plan options and find the one that’s right for you.
Medicare Part A
Medicare Part A covers hospital and inpatient care. It includes services such as inpatient hospital stays, skilled nursing facility care following a hospital stay, hospice care, and some home health care services. Part A is premium-free for most people if they or their spouse paid Medicare taxes while working.
Medicare Part B
Medicare Part B covers medical services and supplies necessary to diagnose or treat a medical condition. This includes services like doctor visits, outpatient care, preventive services, durable medical equipment, lab tests, and home health care services. Part B typically requires a monthly premium that varies based on income.
If you delay in enrolling in Part B when you first become eligible, you may face a late enrollment penalty and gaps in coverage. However, if you or your spouse is still working after 65 and have creditable employer health coverage, you may qualify for a Special Enrollment Period to enroll later without penalty.
Medicare Part C
Medicare Part C, or Medicare Advantage, is a type of Medicare plan offered by private insurance companies approved by Medicare. It combines coverage for hospital services (Part A), medical services (Part B), and sometimes prescription drug coverage (Part D) into a single plan. Part C often includes extra benefits like dental, vision, hearing, and wellness programs.
Medicare Part D
Medicare Part D is the prescription drug coverage part of Medicare. It helps cover the cost of prescription medications. Part D plans are offered by private insurance companies approved by Medicare. Which drugs are covered, deductibles, copays, and premiums vary based on the plan.
Because Part D plans can change each year, it’s a good idea to review and compare your options to make sure your medications are still covered and your costs remain affordable.
What Medicare doesn’t cover
Original Medicare (Part A and Part B) does not cover every health care service, which can lead to out-of-pocket costs for many people. Knowing what isn’t covered can help you plan ahead and decide whether additional coverage may be right for you.
Common services not covered by Original Medicare:
- Routine dental care such as cleanings, fillings, dentures, and dental exams
- Routine vision care, including eye exams, glasses, and contact lenses
- Routing hearing exams and hearing aids
- Prescription drugs are covered separately under Part D
- Health care received outside of the U.S., except in limited situations
To help cover some of these gaps, many people choose additional coverage. Medicare Advantage plans often include extra benefits like dental, vision, hearing, and prescription drug coverage. Medigap (Medicare Supplement) plans can help pay out-of-pocket costs such as deductibles and copays under Original Medicare, and some plans offer limited emergency coverage when traveling outside of the U.S.
Frequently asked questions about the four parts of Medicare
How do I choose which parts of Medicare I need?
The parts of Medicare you need depend on your health needs, your budget, and how you want to receive your coverage. Most people start with Original Medicare. This includes Part A (hospital insurance) and Part B (medical insurance). From there, you choose to add standalone Part D prescription plan and possibly a Medigap plan, or you can enroll in a Part C (Medicare Advantage) plan. Part C plans combine your Part A, Part B, and sometimes Part D into one plan.
When can I enroll in Medicare Parts A, B, C, or D?
Most people first enroll during their Initial Enrollment Period, which starts three months before the month you turn 65, includes your birthday month, and ends three months after your birthday month. You can also enroll or make changes to your coverage during the Annual Enrollment period (Oct. 15 – Dec. 7). You may qualify for a Special Enrollment Period if you delayed enrolling because you were still working and had creditable employer coverage or if you have experienced certain life events.
Can I have both Medicare Advantage and Part D?
No. If you are enrolled in a Medicare Advantage plan that includes prescription drug coverage, you cannot enroll in a separate Part D plan. If you join a standalone Part D plan while having a separate Medicare Advantage plan with Part D included, you would typically be disenrolled from the plan and put back on Original Medicare. Medicare Advantage plans often already include Part D, but if your Medicare Advantage plan does not include drug coverage, you may be able to join a separate Part D plan.
Are all four parts of Medicare required?
No. All four parts of Medicare are not required, but you may face late enrollment penalties later if you don’t sign up for certain parts when you are first eligible. Part A is typically automatic when you sign up for Social Security. Part B is voluntary, but you will need it to cover doctor visits and outpatient care. If you don’t sign up for Part B when you’re first eligible, you will pay penalties later unless you have other creditable coverage. Part C (Medicare Advantage) is an alternative to Original Medicare and includes Part A, Part B, and often Part D in one plan. Part D is optional, but you can face late enrollment penalties if you go 63 days without creditable coverage. You must first sign up for Part A and Part B to enroll in a Part C or Part D plan.
Exploring the different parts of Medicare and their coverage
Medicare resources
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Last Updated: 10/1/2025