A few weeks after a doctor visit, lab test, or hospital stay, your health insurer sends a document labeled “This is not a bill.” That document is your explanation of benefits (EOB), and it is one of the most useful tools you have for controlling medical costs. It shows what the provider charged, what the plan paid, and what you may owe. Reading it carefully before you pay a medical bill can help you catch errors, duplicate charges, and wrongly denied claims.
What an explanation of benefits is
An EOB is a statement from your health plan summarizing how it processed a claim submitted by a provider. Insurers typically send one for each claim, either by mail or through an online member portal. Many plans also issue monthly or quarterly summaries. The EOB is not a request for payment; the bill comes separately from the provider. The EOB tells you what the bill should say.
The key parts of an EOB
Layouts differ by insurer, but most EOBs contain the same core information.
Claim and patient information
- Patient name and member ID
- Provider name, such as the physician, lab, or facility
- Claim number, which you will need if you call the insurer
- Date of service
- Network status, showing whether the provider was in network
Service details
Each service is listed on its own line, often with a description and a procedure code. Procedure codes are usually CPT or HCPCS codes, and diagnosis codes may also appear.
The money columns
| Column | What it means |
|---|---|
| Amount billed (charges) | The provider’s full list price |
| Allowed amount | The maximum the plan recognizes for the service, often a negotiated network rate |
| Discount or adjustment | The difference between billed and allowed that an in-network provider writes off |
| Not covered | Amounts the plan will not pay, with a reason code |
| Plan paid | What the insurer paid the provider |
| Deductible | The part of the allowed amount applied to your deductible |
| Copay / coinsurance | Your cost-sharing under the plan |
| Patient responsibility | The total you may owe the provider |
The allowed amount is the central number. For an in-network provider, your responsibility is calculated from the allowed amount, and the provider generally cannot bill you for the difference between its charge and that amount.
Remark and reason codes
Codes next to a line explain adjustments or denials, with definitions at the bottom of the EOB or on the back. Common reasons include services not covered under the plan, services requiring prior authorization, missing information from the provider, duplicate claims, and out-of-network providers.
Accumulators
Many EOBs show progress toward your deductible and out-of-pocket maximum for the plan year. Once you reach the out-of-pocket maximum, the plan pays 100% of covered in-network services for the rest of the year.
A simple example
Suppose a specialist bills $400 for a visit. The plan’s allowed amount is $180, so the network adjustment is $220. You have met your deductible and owe 20% coinsurance. The plan pays $144, and your patient responsibility is $36. If the specialist later sends a bill for $256 or $400, something is wrong, and you should question it before paying.
How to match an EOB to a medical bill
- Wait for the EOB before paying a provider bill when possible, unless payment is due at the time of service as a copay.
- Match the date of service, provider, and amounts on the bill to the EOB.
- Compare the balance due to the patient responsibility on the EOB.
- Subtract anything already paid, such as a copay at check-in.
- Call the provider’s billing office if the numbers differ. Ask whether the bill was sent before the claim was processed.
Common errors to look for
- Services you did not receive, which can indicate a billing mistake or medical identity theft
- Duplicate charges for the same service on the same date
- Wrong network status for a provider who should be in network
- Coding errors, such as an office visit billed at a higher level than appropriate
- Preventive care billed with cost-sharing. Under the Affordable Care Act, most plans must cover recommended preventive services in network without cost-sharing. If a screening shows a deductible charge, the provider may have coded it as diagnostic.
- Balance billing by an in-network provider for more than your cost-sharing
The No Surprises Act
Since 2022, the federal No Surprises Act has protected people with most private health coverage from surprise balance bills for emergency services, including out-of-network emergency care, and for certain non-emergency services from out-of-network providers at in-network facilities, such as anesthesiologists and radiologists. In those situations, your cost-sharing should be based on in-network amounts. If an EOB or bill does not reflect that protection, you can contact your plan, the provider, or the federal No Surprises Help Desk.
What to do if a claim is denied
- Read the reason code on the EOB and the plan documents.
- Call the provider to see if a coding correction, missing information, or prior authorization fix will resolve it. Many denials are administrative.
- File an internal appeal with your insurer. Under the ACA, most plans must allow you at least 180 days from the denial notice to appeal.
- Request an external review by an independent reviewer if the internal appeal is denied and your case qualifies.
Keep copies of every EOB, bill, and letter, and write down the date, name, and reference number for each phone call.
Why you should read EOBs even if you owe nothing
An EOB showing zero patient responsibility can still reveal fraud, such as services billed under your name that you never received. The Federal Trade Commission recommends reviewing EOBs as a way to detect medical identity theft. Report unfamiliar charges to your insurer promptly.
Organizing your EOBs
- Create an account in your insurer’s member portal for faster access and search.
- Keep EOBs for each family member in a dedicated folder for the plan year.
- Save EOBs as documentation for health savings account or flexible spending account reimbursements.
- Keep records at least until all bills for the year are resolved, and longer if you deduct medical expenses on your taxes.
EOBs for out-of-network care
When you see an out-of-network provider for non-emergency care that is not protected by the No Surprises Act, the EOB often looks different. The allowed amount may be based on the plan’s own fee schedule rather than a negotiated rate, and there is no network discount the provider must honor. That means the provider can bill you the difference between its charge and the allowed amount, known as balance billing. Some plans, especially many HMOs and EPOs, cover no out-of-network care except emergencies, so the EOB may show the entire charge as not covered. If you have PPO or POS coverage with out-of-network benefits, check whether a separate out-of-network deductible and out-of-pocket maximum apply.
Related reading: Medicare IRMAA: How Income-Related Surcharges Work and How to Appeal Them and Special Enrollment Periods: How to Get Health Coverage Outside Open Enrollment.
Frequently Asked Questions
Is an explanation of benefits a bill?
No. It summarizes how your plan processed a claim. The bill comes from the provider and should match the patient responsibility shown on the EOB.
What is the allowed amount on an EOB?
It is the maximum your plan recognizes for a covered service, often the network’s negotiated rate. Your cost-sharing is calculated from it.
Why is my medical bill higher than my EOB?
The provider may have billed before the claim was processed, failed to apply the network discount, or made an error. Call the billing office and reference the EOB.
What should I do if I see a service I did not receive?
Contact the insurer and provider right away, because it may be an error or medical identity theft.
How long do I have to appeal a denied claim?
For most ACA-compliant plans, at least 180 days from the date you receive the denial notice. Check your plan’s notice for exact deadlines.
This article is for general informational purposes only and is not legal, medical, tax, or financial advice. Rules vary by state and change over time; confirm details with the relevant agency or a licensed professional.
