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Medicare Parts A, B, C and D Explained

This article provides a summary of the four parts of Medicare as well as Medicare Supplement. Each of these Parts is explained in detail in subsequent articles under different Categories.

Medicare Parts A, B, C and D Explained

Medicare has four parts:

  • Part A (hospital insurance),
  • Part B (medical insurance),
  • Part C (Medicare Advantage), and
  • Part D (prescription drug plans).

Parts A and B are sometimes also referred to as 'Original Medicare' and are administered by the government. Parts C and D are offered by private carriers through a multitude of Plans. Part C may be viewed as a substitute for Medicare Parts A and B.

There is also supplemental coverage available to Medicare Parts A & B, called Medicare Supplement (sometimes also referred to as Medigap), which is provided by private insurance companies through various types of plans.

Remember that coverage has associated costs like monthly premiums, deductibles and copays/ coinsurance for covered services.

PART A (hospital insurance)

Hospitalization is expensive. Part A offers coverage for hospitalization, skilled nursing facility, home health services, and hospice.

You may qualify for premium-free Part A if you have worked and paid Social Security taxes for at least ten years or forty calendar quarters (most people qualify). If you do not meet the work and tax payment requirements, a monthly premium may be charged based on the number of quarters for which you worked and paid social security taxes.

Hospitalization includes acute care hospitals, critical access hospitals, inpatient rehabilitation facilities, long-term care hospitals, inpatient care which is part of a qualifying clinical research study, and mental health care.

Coverage is provided for stays in a general hospital for up to 90 days each 'benefit period', plus 60 lifetime reserve days. If you need psychiatric care, you can stay in a Medicare-certified specialty hospital for up to 190 lifetime days.

Part A coverage also gives you access to occupational therapy, durable medical equipment needed during the stay, medical social services, speech pathology services, skilled nursing gear and part-time home aide services. Wheelchairs, walkers, laboratory tests, surgeries and doctor visits are covered under Part A if deemed medically necessary to treat inpatients.

Skilled nursing facility (SNF) care:

You are eligible for SNF care if you have been in a hospital for at least three consecutive days in the 30 day period before admission and need skilled nursing services on a daily basis. Coverage includes up to 100 days each 'benefit period'. It also allows physical, occupational or speech therapy services five days a week.

Home health care:

You can avail up to 100 days of home health care provided you have been in a hospital for at least three days in the 14 days before receiving care, and you are homebound. 

PART B (medical insurance)

Part B covers services such as those provided by your doctor, clinical laboratory ( e.g., x-rays, scans); mental health care; outpatient services; preventive care; physical and occupational therapy; chiropractic care; home health and ambulance facility and any durable medical equipment that you may require for assisted living. It also pays for prescription drugs given as part of covered outpatient treatment.

In case you need a second opinion from another surgeon before surgery, Part B allows you to do so.

Part B premium is tied to your income. High-income earners pay a higher premium.  

PART C (Medicare Advantage plans or MA plans)

Part C may be viewed as a substitute for Medicare Parts A and B, combining hospital and medical insurance. Part C plans are offered by various private carriers. Many times, additional benefits are included in the coverage as compared to Parts A and B.

Remember, you will still need to pay a monthly premium for Part B, the difference being that Part B benefits are now offered through Part C. Naturally, Part C premium does not include Part B premium.

Many plans combine Part C with Part D prescription drug coverage. These are called MA-PD plans. 

One of the advantages of having an MA plan is that you may get extra coverage for medical problems related to vision, hearing, dental and health/wellness programs.

MA plans are usually offered as Medicare Advantage HMO plans, Medicare Advantage PPO plans, Medicare Advantage Private-Fee-for-Service (PFFS) plans, and Medicare Advantage Special Needs Plans (SNP).

PART D (Prescription Drug Plan or PDP)  

Part D provides outpatient prescription drug coverage.

It is available only through approved private insurance companies who have tie-ups with the Medicare program. If you have Medicare Parts A or B, it is advisable that you choose a stand-alone Part D plan. Or you may want to go for a combined MA and PDP plan, also called a Medicare Advantage Prescription Drug (MA-PD) Plan. In some cases, a standalone MA plan may be combined with a standalone PDP plan as well.

PDP or MA-PD Plans have a list of covered drugs known as formularies. Each plan’s formulary may cover drugs through a tiered system, with each tier costing differently. Make sure that the drugs you take are 1) covered by your plan’s formulary, and 2) the plan’s formulary puts them or their generic equivalents in lower-priced tiers.

Medicare Supplement Plans

Medicare Supplement is additional health insurance that you may buy to cover many health care costs not covered by Medicare Parts A & B. These include co-payments, deductibles, and (in some plans) emergency health coverage if you travel outside the US. 

If you have a Medicare Advantage plan, you cannot get a Medicare Supplement plan since it only works with Medicare Parts A and B.

Medicare Supplement plans are standardized into various Types. Click here for more information on these plan types and the coverage they offer.


Click here to learn more about Medicare, its various Parts, different enrollment periods and your costs. 

We have also created videos to help you better understand various topics related to Medicare. Select and watch a video explaining the topic of your interest in a simple and intuitive manner.

Remember that you cannot choose just any combination of Parts and Plans. Let Lighted Road Insurance guide you step-by-step through the Medicare ecosystem and help you in selecting the right plan(s) for your needs. 

General / Informational Disclaimers

This website ( contains information about and access to insurance plans for eligible and soon to be eligible Medicare beneficiaries and their advisors. It is operated by Lighted Road Insurance Services, a licensed health insurance agency in the State of California. and Lighted Road Insurance Services are not endorsed by the Centers for Medicare & Medicaid Services (CMS), the Department of Health and Human Services (DHHS), or any other government agency.

For a complete list of available plans please contact 1-800-MEDICARE (TTY users should call 1-877-486-2048), 24 hours a day/7 days a week or consult

The purpose of this communication is the solicitation of insurance. Contact may be made by an insurance agent/producer or insurance company. Enrollment in any plan depends on contract renewal.


Last Updated: 01-10-2021