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Part of: Understand your denial

Guide · the basics · 4 minute read

How to read an Explanation of Benefits

What the lines on an Explanation of Benefits mean, how to tell what you owe from what was refused, and why you should not pay from it alone.

Applies to: Any coverage

Key points

  • An Explanation of Benefits is a statement about how a claim was handled. It is not a bill.
  • Find two things first: what the plan paid and what it says you may owe.
  • Any line with a denial or a reason code is worth reading closely.
  • Medicare sends its own version, the Medicare Summary Notice.
On this page 7

An Explanation of Benefits (EOB) is a statement from your plan about how it handled a claim. It is not a bill, and it is not always a denial. Find two figures first: what the plan paid and what it says you may owe. Then look for any line the plan refused to pay, and read the reason beside it.

What this means

Layouts differ from plan to plan, but most EOBs show the same pieces:

  • Provider and date of service. Who treated you and when.
  • Amount billed. What the provider charged.
  • Allowed or plan rate. What the plan counts as the price for that service.
  • Amount the plan paid. Its share.
  • What you may owe. Often called “patient responsibility”. It is made up of your deductible (what you pay before the plan starts to pay), copayment (a set fee) and coinsurance (a percentage).
  • Amounts not covered or denied, with a reason or remark code. This is the part to read most closely.

Example with made-up amounts. A provider bills $500. The plan’s rate for the visit is $200. The plan pays $150 and your copayment is $50, so the EOB says you may owe $50. The other $300 is the difference between the charge and the plan rate, which for an in-network provider is normally not billed to you. A second EOB may follow for a lab or a facility fee tied to the same visit.

What to do

  1. Match the EOB to the visit. Check the provider, the date and the service. If something is wrong, tell your provider and your plan.
  2. Find “you may owe” and compare it with any bill. If the provider bills more than the EOB says, call the billing office before you pay. The bill and statement reconciler helps you compare them.
  3. Find every line that was not paid, and read its reason. Use the EOB decoder if the wording is hard to follow.
  4. Decide which of three things it is: your ordinary share, a rejected claim that needs fixing, or a denial. The guide to denied, rejected, or just your share explains each.
  5. Ask for the codes if they are not clear. Non-grandfathered plans and insurers must give you the diagnosis code and treatment code, and what they mean, “as soon as practicable” on request. Asking for them cannot be treated as filing an appeal.
  6. Keep every EOB. Put it with the bill and the letter, and add notes about calls to your call log.

If you have Original Medicare

Original Medicare sends a Medicare Summary Notice (MSN). It is the written notice of the initial decision on a claim, it must give the reasons for the decision and explain how to ask for a first appeal, and it is not a bill. Medicare.gov says the paper MSN is mailed every 6 months if you received services in that period, and electronic notices are available monthly. Many websites still say every 3 or 4 months. A first appeal, called a redetermination, must be filed within 120 calendar days of receiving the notice. Receipt is presumed to be 5 calendar days after the date on the notice (check the date on your notice, which controls). See the five levels of Original Medicare appeal.

What the EOB may say, and what to say back

“This is not a bill.” Correct. Do not pay from the EOB alone. Wait for the provider’s bill, then compare the two.

“Patient responsibility: not covered.” Ask the plan what provision makes the service not covered. If the reason is medical necessity or a limit, an appeal may be possible.

“Claim denied” with a code you do not recognize. Write to the plan and ask what the code means and which plan rule applies.

The rule

A non-grandfathered private plan or insurer must give the diagnosis code and treatment code, and their meanings, as soon as practicable on request, and asking for them cannot be treated as filing an appeal or an external review request. Source: Code of Federal Regulations (CFR) Title 29, section 2590.715-2719(b)(2)(ii)(E), the federal appeals regulation.

Watch for

  • Several EOBs for one visit. A surgeon, a facility, an anesthesiologist and a lab may each be processed separately.
  • A bill that does not match the EOB. Ask the provider to explain the difference. Do not assume either document is right. See a bill is not an EOB.
  • Out-of-network surprises. If you were treated at an in-network place by someone who is out of network, use the surprise bill checker.
  • A denial is a separate letter. Some plans send the EOB first and the formal denial notice later. Do not wait for the letter if your EOB already shows a deadline.

What next

Sources

Official and primary sources used on this page. Checked 2026-11-12.

  1. 42 CFR 405.921, notice of initial determination (Medicare Summary Notice) — Electronic Code of Federal Regulations
  2. Medicare Summary Notice — Medicare.gov
  3. 29 CFR 2590.715-2719, internal claims and appeals and external review (diagnosis and treatment codes) — Electronic Code of Federal Regulations
  4. 42 CFR 405.942, time for filing a redetermination request — Electronic Code of Federal Regulations

What next

Letters and scripts

  • Letter or script

    Ask for your claim file

    A written request for everything the plan used or created when it decided your claim, sent before you appeal. It asks for the file free of charge and says clearly that it is not an appeal.

  • Letter or script

    Ask for an itemized bill

    A written request to a provider for an itemized statement of every charge, code, payment and adjustment on your account, so you can compare it with your plan's Explanation of Benefits before paying.

  • Letter or script

    Ask the provider to hold the bill

    Ask a provider in writing to pause collection, interest and late fees on a bill while your insurance appeal is decided.

Tools

Checklists

  • Checklist

    The bill while you appeal

    How to keep a bill from getting worse while your appeal is pending, check what you actually owe, and look for ways to reduce it.

Related guides

Denial reasons

  • Denial reason

    Coding or billing error

    The claim itself has a wrong code, a wrong detail or a missing item. Your provider's billing office usually has to correct it and send it again. You help by asking for the codes, checking them against your records and following up.

  • Denial reason

    Duplicate claim

    The plan thinks it already received or paid this claim. Check your Explanation of Benefits for the first claim. If the services are separate, your provider's billing office has to show the plan that.

  • Denial reason

    Allowed amount too low

    Your plan paid an out-of-network provider only part of the bill and says the rest is above its allowed amount. Check how the plan set that amount, whether surprise-billing protections apply, and what typical prices are in your area.

This page is general information, not legal or medical advice. Your notice, your plan document and the law that applies to your coverage control.

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