How to Read Medicare EOBs and MSNs

Christian Worstell
In this article...
  • Learn how to read your Medicare explanation of benefits (EOB) and Medicare summary notice (MSN) so you can better understand your insurance benefits and how much you might owe for services. Learn more about these important Medicare documents.

EOB stands for explanation of benefits. MSN stands for Medicare summary notice. Both of these documents help you understand how your Medicare benefits are being used and how much you may owe out-of-pocket.

Find out how to read Medicare EOBs and MSNs below to better understand your Medicare benefits and manage your health care costs.

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How to Read Medicare EOBs

Medicare EOBs are sent each time Medicare processes a claim from one of your health care providers. You should receive one a few weeks or so after any medical services.

Medicare EOBs can look different depending on which type of Medicare payer they're coming from. But they generally contain the same information, so here's what to look for on these documents:

  • How much the provider charged. This is usually listed under a column titled "billed" or "charges."

  • How much Medicare allowed. Medicare has a specific allowance amount for every service. It usually provides a breakdown on the EOB for what was disallowed (sometimes called a UCR write-off) and what was allowed. If Medicare doesn't allow the charges, typically you don't have to pay them.

  • How much Medicare paid. For each allowed charge, Medicare will pay a certain percentage, ranging up to 100%.

  • How much was put toward patient responsibility. The portion of allowed charged Medicare didn't pay is typically listed separated under a column for "your responsibility" or "patient responsibility." This is how much you may have to pay unless you have secondary insurance that might kick in to pay some.

EOBs also usually have codes, known as reason codes. These codes help tell the provider why Medicare didn't pay for something so the provider's billing office can follow up. Usually, you don't need to worry that much about these codes. However, the codes may be explained on the bottom of the EOB if you're interested. You can also call your Medicare customer service line to ask about the codes or why certain claims weren't paid.

What Should You Do With EOBs?

You should always review your EOBs to ensure everything looks correct and that they match up to any bills or statements you receive from your health care provider. You might also want to keep the EOBs until the medical claims are paid in full so you have a complete record of what is going on with your claims.

If you suspect that providers are billing Medicare for services that weren't provided to you, you can call your Medicare customer service line to report it. You can also talk to your provider if the patient responsibility on your Medicare EOB is less than what you were billed, as that might indicate a mistake in billing.

How to Read Medicare MSNs

You receive a Medicare Summary Notice every quarter that you receive Medicare-covered health care services. The notice summarizes how much Medicare paid for services during that period and how much you may owe out-of-pocket.

You'll get MSNs for Part A and B coverage under Medicare. The four-page documents include the summary of charges and an update on how much of your deductible has been met for the year. It also includes a claims page that breaks down all the claims filed in that period, whether they were paid and what you might owe out-of-pocket.

Other pages in your MSN include tips for reviewing the MSN and some guidance on what you can do if Medicare denied any of the claims.

It's a good idea to compare your MSN to any EOBs you received through the quarter as well as bills from your medical providers. This helps you ensure all your claims are being billed accurately and what you're being asked to pay by providers is correct.

You can get your Medicare Summary Notice online if you create an account at There's an option under messages for getting your MSN electronically instead of in the mail.

You may want to hold on to your MSNs for up to a year to ensure claims are all fully settled. If you claim medical payments on your taxes, you may want to keep these documents for up to seven years so you have them if you're ever audited.

Christian Worstell
About the Author

Christian Worstell is a senior Medicare and health insurance writer with He is also a licensed health insurance agent. Christian is well-known in the insurance industry for the thousands of educational articles he’s written, helping Americans better understand their health insurance and Medicare coverage.

Christian’s work as a Medicare expert has appeared in several top-tier and trade news outlets including Forbes, MarketWatch, WebMD and Yahoo! Finance.

While at HelpAdvisor, Christian has written hundreds of articles that teach Medicare beneficiaries the best practices for navigating Medicare. His articles are read by thousands of older Americans each month. By better understanding their health care coverage, readers may hopefully learn how to limit their out-of-pocket Medicare spending and access quality medical care.

Christian’s passion for his role stems from his desire to make a difference in the senior community. He strongly believes that the more beneficiaries know about their Medicare coverage, the better their overall health and wellness is as a result.

A current resident of Raleigh, Christian is a graduate of Shippensburg University with a bachelor’s degree in journalism. You can find Christian’s most recent articles in our blog.

If you’re a member of the media looking to connect with Christian, please don’t hesitate to email our public relations team at

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