Christian Simmons, writer and researcher for RetireGuide
  • Written by
    Christian Simmons

    Christian Simmons

    Financial Writer

    Christian Simmons is a writer for RetireGuide and a member of the Association for Financial Counseling & Planning Education (AFCPE®). He covers Medicare and important retirement topics. Christian is a former winner of a Florida Society of News Editors journalism contest and has written professionally since 2016.

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  • Edited By
    Lamia Chowdhury
    Lamia Chowdhury, editor for

    Lamia Chowdhury

    Financial Editor

    Lamia Chowdhury is a financial content editor for RetireGuide and has over three years of marketing experience in the finance industry. She has written copy for both digital and print pieces ranging from blogs, radio scripts and search ads to billboards, brochures, mailers and more.

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  • Published: April 16, 2020
  • Updated: November 15, 2022
  • 14 min read time
  • This page features 9 Cited Research Articles
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How to Cite's Article

APA Simmons, C. (2022, November 15). What Is Medicare? Retrieved December 7, 2022, from

MLA Simmons, Christian. "What Is Medicare?", 15 Nov 2022,

Chicago Simmons, Christian. "What Is Medicare?" Last modified November 15, 2022.

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Key Principles

RetireGuide’s mission is to provide seniors with resources that will help them reach important financial decisions that affect their retirement. Our goal is to arm our readers with knowledge that will lead to a healthy and financially sound retirement.

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Key Takeaways
  • Medicare is divided into four different parts. Parts A and B make up Original Medicare, Part C is often known as Medicare Advantage (which is provided by private insurers), and Part D is prescription drug insurance.
  • Original Medicare (Parts A and B) is a federal health plan that becomes available once you turn 65 years old. Original Medicare does not cover everything. Routine prescription drugs, dental, vision and hearing are a few of the necessary services not covered.
  • You generally pay a deductible for your health care before Medicare pays its share. Medicare will then take over and you pay the coinsurance or copayment for covered services and supplies.
  • There are optional Medicare plans that you can purchase during select enrollment periods. These plans cover the additional health care costs not covered by Original Medicare. These plans vary by state and include Medicare Advantage plans, supplement insurance (Medigap) and Part D prescription drug coverage.

Medicare Explained

Medicare is the most common form of health care coverage for seniors. The program provides a way for older Americans to have their health needs taken care of after they retire from the workforce.

The Medicare program was originally founded in 1965. At that time, what is now known as Original Medicare was created. The first major expansion to the program came seven years later, when people with disabilities or end-stage renal disease became qualified for coverage.

Part C was originally established in 1997 and was first known as the Medicare+Choice program. It took on its modern form and was renamed as Medicare Advantage a few years later in 2003.  Part D took effect starting in 2006.

The Medicaid program was founded at the same time as Medicare as well. Medicaid was originally created to provide insurance to those who needed cash assistance but has been expanded beyond that since. The program is separate from Medicare and exists today to provide health care to low-income Americans.

The basics of Medicare include both plans that are provided by the federal government and ones that are available through private insurers. Different types of plans can cover different parts of your health care.

Understanding Medicare Coverage Plans

Medicare is divided into four parts, named alphabetically from Part A through Part D.

Parts A and B are sometimes referred to as Original Medicare. Parts C and D are newer options. Generally, you can get coverage through Original Medicare or through Medicare Advantage plans if you qualify.

Medicare Advantage plans require that you live in the service area of the plan you want to join.

Original Medicare

Original Medicare is provided through the federal government. Americans are typically eligible to enroll in Original Medicare when they turn 65. It is divided into Parts A and B, which each handle different parts of your health care.

It’s important to remember that Original Medicare does not cover everything, with notable areas like vision and dental coverage excluded.

Medicare Part A

Medicare Part A is hospital insurance. It covers the costs of a hospital or nursing facility stay, but does not cover long-term care.

What does Medicare Part A cover?
  • Inpatient care in a hospital
  • Inpatient care in a skilled nursing facility
  • Home health care
  • Hospice care

Part A does not cover the costs of treatments you receive while in the hospital. That falls under Part B.

Medicare Part B

Medicare Part B is medical insurance that covers doctor visits. It also covers the costs of what CMS calls medically necessary services and preventative services.

  • Medically necessary services include those supplies, tests or other services to diagnose and treat your medical condition.
  • Preventative services include health care required to detect and treat a condition early on.

Medicare Advantage Plans (Part C)

Medicare Part C is also called Medicare Advantage, a form of private insurance. Enrollment in Part C is voluntary.

These plans are sold through insurance firms that have contracted with the federal government. All Medicare Advantage plans must provide the same coverage as Medicare Part A and Part B, but other benefits vary from plan to plan.

Most Medicare Advantage plans also offer prescription drug coverage. Medicare Advantage plans may also bundle coverage beyond what Original Medicare plans cover and may include vision, hearing and dental coverage.

What Can Medicare Advantage Include?
  • Vision Coverage
  • Dental Coverage
  • Prescription Drug Coverage
  • Other Additional Benefits

Medicare Advantage plans are provided regionally, so specific benefits and coverage available can vary based on where you live and the plans that are sold in your area.

Annual Enrollment Ends December 7th
Have you selected your 2023 Medicare plan? The Medicare Annual Enrollment period ends tomorrow. Visit GoHealth today to see what savings you may qualify for with a new plan.

Medicare Part D (Prescription Drugs)

Medicare Part D covers the cost of prescription drugs and is provided through private insurers. People who enroll in Part D pay a monthly premium. It covers the prescription drugs you buy at your local or mail-order pharmacy.

Most states have more than two dozen private insurers to choose from for Part D coverage. You can often receive prescription drug coverage through a Medicare Advantage plan, essentially combining Parts C and D.

You can also purchase a standalone drug plan to pair with Original Medicare. Different Part D plans come with their own formulary, and there may be some variety in what drugs they cover.

Medicare Supplement Plans (Medigap)

A Medicare Supplement plan, commonly known as Medigap, is an additional coverage option to Original Medicare.

Medicare Part A and Part B only covers 80 percent of services. Adding a Medigap plan covers the remaining 20 percent, eliminating coinsurance or copayments as well as some additional out-of-pocket costs.

What Medigap Can Cover
  • Coinsurance
  • Copayments
  • Deductibles

These policies are sold by private insurance companies. If you have Medicare Advantage, you cannot pair your coverage with supplemental insurance. Medigap is only meant to help with Original Medicare.

Comparing Medicare Plans

When trying to find the best Medicare plan for you, it’s important to be aware of and compare all your options. Having a solid understanding of the differences between each type of plan can help you narrow down your choices.

Types of Medicare Coverage
  • Original Medicare
  • Medigap
  • Medicare Advantage
  • Part D Prescription Drug Coverage

When comparing plans, one of the first things you should determine is how much money you are willing or able to spend on your health care coverage. This can help you narrow down your initial options.

You also should make a list of certain conditions or services that are a must for you and should be included in your plan. If you have coverage needs that aren’t available under Original Medicare, it can play a key role in determining if Medicare Advantage is the best option for you.

You will also have to consider where you live if you decide to opt for Medicare Advantage. These plans are available regionally and can vary from city to city. You are likely to have more options if you live in a populated area.

Medicare Advantage plans and Part D plans also come with a star rating system based on what they provide and how well they do. Be sure to take star ratings into account when choosing between plans.

How to Choose a Medicare Plan
  • Determine how much you can spend on health care.
  • Figure out what treatments, services or coverage are most important to you.
  • Look into Original Medicare and Medigap.
  • Compare Medicare Advantage and Part D plans available in your area.
  • Compare plan ratings.
Read More About Choosing a Medicare Plan

It’s also important to continuously compare plans each year during enrollment periods. Coverage and plans available near you can change year to year, opening new and potentially better coverage options.

Medicare Enrollment and Eligibility

Not everyone qualifies for Medicare Parts A and B. Still, others may be able to get it if they pay premiums.

Requirements to qualify for premium-free Medicare Part A at age 65 or older:
  • You or your spouse had Medicare-covered government employment.
  • You or your spouse has worked long enough (usually 10 years) to qualify for Social Security and paid Medicare taxes.
  • You are receiving retirement benefits from Social Security or the Railroad Retirement board. Or you are eligible to receive Social Security or Railroad benefits but you have not filed for them.

If you or your spouse didn’t pay Medicare taxes while working but are a U.S. citizen or legal permanent resident and 65 or older, you may be eligible to buy Medicare Part A coverage.

You can also qualify for premium-free Medicare Part A if you are under 65 and require dialysis or are a kidney transplant patient. People younger than 65 diagnosed with Lou Gehrig’s disease (ALS) also qualify the first month after they receive disability benefits.

Find out if you are eligible for Medicare and how much your expected premium would cost with the Eligibility Tool.
Source: U.S. Centers for Medicare & Medicaid Services

As far as signing up for Original Medicare if you are eligible, you’ll be automatically enrolled when you turn 65 if you are already receiving Social Security benefits.

Three Ways to Enroll in Medicare
  • Online at the Social Security website. It takes less than 10 minutes, according to the Social Security Administration.
  • A toll-free phone call to 1-800-772-1213 from 7 a.m. to 7 p.m., Monday through Friday. Deaf and partially deaf people can call TTY 1-800-325-0778.
  • In person at your local Social Security office, but you are required to call first to make an appointment.

You should sign up during your 65th birthday month or sometime in the three months before or after your birthday month. If you miss this window, you may face permanent financial penalties.

If you are new to Medicare, you have several periods when you can enroll or change your plan, even if you don’t know when you first become eligible.

Medicare Enrollment Periods

Initial Medicare Enrollment Period
Runs from the three months leading up to your 65th birthday to the three months after.
General Medicare Enrollment Period
Runs from Jan.1 to Mar. 31 and can be used if you missed your initial enrollment window.
Special Enrollment Period
Only available under specific circumstances, like a move or sudden loss of coverage.

Medicare Cost and Coverage

There are costs and fees associated with Medicare. These include premiums, deductibles and coinsurance. You may also pay penalties for waiting to enroll in Medicare Part B.

Most people don’t have to pay a premium for Medicare Part A because they paid for it through years of payroll taxes while they worked.

Definitions to Know
Your monthly payment in exchange for coverage.
The amount you have to pay for medical care or prescriptions before Medicare Part A, Part B, Part D or your Medicare Advantage plan starts to pay.
A cost you may be required to pay for your share of medical services after paying any deductibles. It’s usually measured as a percentage of the bill.
Lifetime Reserve Day
Additional days Medicare pays for when you are in a hospital for more than 90 days. You have 60 of these for your entire lifetime. Medicare pays all covered costs, except coinsurance, for each of these days you use.

Medicare premiums are updated annually and depend on a variety of factors. Economic and political factors have a high influence on Medicare changes.

Out-of-Pocket Medicare Costs in 2023
Part A Premium
  • Most people pay no premium
  • Up to $506 /month (in 2023) if you buy Part A coverage
  • $506 /month if you worked and paid Medicare taxes for fewer than 30 quarters (7.5 years)
  • $278/month if you worked and paid Medicare taxes for 30 to 39 quarters (7.5 to 9.75 years)
Part A Hospital Inpatient Deductible and Coinsurance
  • $1,600 deductible per year
  • $0 coinsurance for first 60 days you’re hospitalized
  • $400 coinsurance for days 61 to 90 of your hospitalization
  • $800/day coinsurance per each lifetime-reserve day after day 90 in the hospital
  • All costs for anything beyond all remaining lifetime-reserve days (you have 60)
Part B Premium
  • $164.90 – It may be higher if you have a higher income
Part B Deductible and Coinsurance
  • $226 deductible
  • 20 percent of all costs after your deductible is met
Part C Premium
  • Monthly premiums vary by plan
Part D Premium
  • Monthly premiums vary by plan
  • People with higher incomes pay higher premiums

What Medicare Does Not Cover

Medicare Parts A and B do not cover everything. Medicare Advantage plans may offer extra benefits that Original Medicare does not cover.

Services and Items Not Covered by Medicare Parts A and B
  • Long-term (custodial) care
  • Most Dental Care
  • Dentures
  • Routine eye exams for prescription lenses
  • Cosmetic surgery
  • Hearing aids and hearing aid exams
  • Routine foot care
  • Acupuncture

The most expensive thing Medicare Parts A and B does not cover is long-term care. Medicaid, another federal health insurance, will sometimes cover these costs, but generally only for low-income Americans with little or no savings.

John Clark, licensed insurance advisor and owner of Senior Solutions Insurance Agency, lists the medical services not covered by Original Medicare.

Medicare-Covered Services

While Original Medicare does not cover everything, there are many services that are covered under Parts A and B. Each part will cover different types of services.

Part A-Covered Services
  • Hospital Stays
  • Skilled Nursing Facility Stays
  • Hospice Care

Part A can take care of most of your services that involve stays in facilities. But remember that Original Medicare does not cover long-term care or something like a permanent move to a nursing home.

Part B covers your everyday health care services, like check-ups and equipment.

Part B-Covered Services
  • Doctor Visits
  • Durable Medical Equipment
  • Ambulance Services
  • Diagnostic Tests

Medicare Advantage plans can sometimes include coverage for these services that go beyond the scope of Original Medicare.

Medical Treatments Covered Under Medicare

Original Medicare can cover a wide range of treatments for many different conditions or ailments. The guiding principle for much of Medicare’s coverage is that a treatment considered a medical necessity should be covered.

Whether something is medically necessary can sometimes be up for interpretation, but there are several areas that Parts A and B can be counted on to provide coverage for.

Examples of Conditions and Treatments Covered Under Medicare
  • ALS
  • Chemotherapy
  • COPD Treatment
  • End-Stage Renal Disease
  • Heart Disease
  • Hip and Knee Replacements
  • Medically Necessary Surgery

Parts A and B can cover many treatments for several conditions if care for them is shown to be medically necessary. Also keep in mind that Medicare rarely covers the entire cost of a treatment. You may still have to pay a significant amount out of pocket depending on the type of care you are receiving.

There are some situations where Original Medicare can cover the diagnosis of a condition, but not necessarily treatment for it. For example, you would be covered for a bone density test to determine if you have osteoporosis, but drugs to treat it would only be covered if you had a Part D plan as well.

Customer Service for Medicare

There are several different ways to get in contact with Medicare Customer Service if you have questions about your plan or want to resolve an issue.

Medicare can be reached by phone at 1-800-MEDICARE (1-800-633-4227) at any time of day. You can also contact Medicare by sending a letter by mail or by emailing them. When calling, make sure you have your Medicare card ready and a way to take notes or record the information you get.

You can call Medicare to resolve several issues, from cost and billing information to coverage or medical record questions.

Frequently Asked Questions About Medicare

How do I get a Medicare card?
If you are automatically enrolled because you are already drawing Social Security benefits, you will receive your card three months before your 65th birthday or your 25th month of drawing disability benefits. If you enroll online, by phone or at your local Social Security office, you’ll receive your card in the mail.
Does Medicare cover dental and vision?
Original Medicare, Parts A and B, do not cover dental and vision. But a Medicare Advantage plan (Part C) may cover them. You should ask about the coverage your Part C plan offers before you purchase it.
What is the difference between Medicare and Medicaid?
Both Medicare and Medicaid are administered by the same federal agency, the Centers for Medicare and Medicaid Services. Medicare is a federal health insurance program for people 65 and older, or younger than 65 if they have a disability. Medicaid is a joint state and federal program that provides health insurance coverage to people with very low incomes.
Last Modified: November 15, 2022

9 Cited Research Articles

  1. U.S. Centers for Medicare & Medicaid Services. (2022, September 27). 2023 Medicare Parts A and B Premiums and Deductibles 2023 Medicare Part D Income-Related Monthly Adjustment Amounts. Retrieved from
  2. U.S. Centers for Medicare and Medicaid Services. (2022, January 26). Trustees Report & Trust Funds. Retrieved from
  3. U.S. Department of Health and Human Services. (2014, September 11). Who is Eligible for Medicare? Retrieved from
  4. U.S. Centers for Medicare and Medicaid Services. (n.d.). What’s Medicare? Retrieved from
  5. U.S. Centers for Medicare and Medicaid Services. (n.d.). What Part A Covers. Retrieved from
  6. U.S. Centers for Medicare and Medicaid Services. (n.d.). What Part B Covers. Retrieved from
  7. U.S. Centers for Medicare and Medicaid Services. (n.d.). What Medicare Health Plans Cover. Retrieved from
  8. U.S. Centers for Medicare and Medicaid Services. (n.d.). Is My Test, Item or Service Covered? Retrieved from
  9. U.S. Centers for Medicare and Medicaid Services. (n.d.). What’s Not Covered by Part A & Part B? Retrieved from