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Understanding Medicare

Your Medicare questions answered: Who is eligible, how to apply, and more

October 1, 2022
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A stethoscope over the word Medicare

You have probably heard of Medicare. Perhaps a family member has it, or maybe you will be eligible soon. But understanding Medicare coverage can be confusing.  

This article is the first in a series designed to help you understand the basics. Continue reading to learn what Medicare is, who is eligible, what the different parts are, how to sign up, and more. 

Medicare is a U.S. federal health insurance program. It is available for: 

  • People who are 65 or older 
  • Certain younger people with disabilities 
  • • People with ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease)
  • People with end-stage renal disease (sometimes called ESRD) 
      • Learn more about Medicare and ESRD here.

Check if you may be eligible for Medicare using the Medicare Eligibility Tool.1 

There are three parts of Medicare. Each part helps cover specific services. A brief summary of each part is below. 

Medicare Part A  

Part A is hospital insurance. It covers hospital stays, care in a skilled nursing facility, hospice care, and some home healthcare. Medicare Part A is part of Original Medicare, which is described later in this article.   

Medicare Part B 

Part B is medical insurance. It covers services from doctors and other healthcare providers, outpatient care, medical supplies, and preventive services. Medicare Part B is part of Original Medicare, which is described later in this article.   

Medicare Part D 

Part D is prescription drug coverage. It helps cover the cost of prescription medications, including many shots and vaccines. Medicare Part D is not part of Original Medicare, but everyone who qualifies for Medicare can sign up for this extra coverage. 

Medicare Part C 

Part C is also known as Medicare Advantage. It is an “all in one” plan option you can sign up for instead of Original Medicare. It includes all benefits and services covered under Part A, Part B, and usually Part D. When you sign up for a Part C Medicare Advantage plan, you do not lose any of the benefits from Original Medicare.  

To learn more about Medicare Advantage, read the article Your Medicare Advantage Questions Answered.

Original Medicare includes Part A (hospital insurance) and Part B (medical insurance).  

Under Original Medicare, you pay for services as you get them. You will pay a deductible at the start of each year and you usually pay 20% of the cost of the Medicare-approved service. This is called co-insurance. Additional resources are available for some people to help pay their out-of-pocket costs, like deductibles.  

If you need drug coverage, you can add a separate drug plan (Part D). 

Learn more about how Original Medicare works.1 

If you are collecting Social Security retirement or disability benefits, you will be automatically enrolled. If you are not collecting Social Security retirement or disability benefits, you can sign up during a seven-month enrollment period. This seven-month period is: 

  • The three months before your birthday month 
  • The month of your birthday 
  • The three months after your birthday month 

If you are eligible for Medicare because of a disability, Medicare Part A and B coverage begins after 24 months of collecting Social Security disability benefits. You do not need to do anything to enroll. Your Medicare card will be mailed to you about three months before your Medicare entitlement date.  

If you are turning 65, Medicare Part A and B coverage begins on the first day of the month that you turn 65. If your birthday falls on the first of the month, coverage begins on the first day of the month prior to your birthday. You do not need to do anything to enroll. Your Medicare card will be mailed to you about three months before your 65th birthday. 

Learn more on the U.S. Department on Health and Human Services website.1 

Some people get Medicare automatically, but some need to sign up. If you are 65 years old (or almost 65) and are not getting Social Security, you may have to sign up for Medicare. 

Check your eligibility using the Medicare Eligibility Tool.1 

To apply for Medicare online, visit 

To apply over the phone, call 1-800-772-1213. 

If you would like to contact your local Social Security office, you can look up its phone number here.1 

Getting Medicare can be a major milestone in someone’s life. Hopefully this article has helped you understand how Medicare works and given you the tools to make the best coverage choices for you.  

1 When you click this link, you will leave the Commonwealth Care Alliance website.


This article was originally posted on October 1, 2021 and updated in October 2023.

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