Reading an EOB and a Medical Bill

When you receive care in the US health system, you typically receive two separate documents: an Explanation of Benefits (EOB) from your insurance company and a bill from the provider. Understanding how to read both — and how to check them for accuracy — can prevent overpaying and help you catch common billing errors.

What an Explanation of Benefits contains

An Explanation of Benefits is sent by your insurer after a claim is processed. It is not a bill — it is a record of how your insurance plan processed the claim. EOBs are typically available online through your insurer’s member portal within days of a claim being processed, or mailed in paper form.

A typical EOB includes:

• Provider information: The name and address of the provider or facility that submitted the claim.
• Date of service: When the service was performed.
• Billed amount: What the provider originally charged.
• Allowed amount (negotiated rate): The amount your insurer and the in-network provider have contractually agreed the service is worth. This is generally lower than the billed amount.
• What the plan paid: The portion of the allowed amount covered by your insurance.
• Your responsibility: The amount you owe — including any deductible payment, copay, or coinsurance.
• Adjustment reason codes: If the full amount was not covered, reason codes explain why — for example, service not covered, deductible not yet met, or prior authorization required.

Review each line of your EOB carefully. The “your responsibility” line is what you should expect on the provider’s bill. If the provider bills you for more than this amount for in-network services, that is a potential balance billing problem.

Understanding the provider bill

The bill from your provider or facility will show the charges, your insurance payment, and any remaining balance. It may not be as detailed as the EOB. If you want to verify the accuracy of the charges, request an itemized bill.

An itemized bill lists every individual service, supply, medication, and procedure separately, along with the billing code (such as a CPT code for procedures or an NDC code for drugs) and the individual charge for each item. Itemized bills can be several pages long for a hospital stay or complex procedure. You have the right to request one at any time — providers are required to provide it.

Common billing errors and what to look for

Billing errors are common in US healthcare. Studies by patient advocacy groups and government agencies have documented high rates of billing mistakes. Common types include:

• Duplicate charges: The same service billed more than once.
• Unbundling: Separate billing for services that should be billed together at a lower combined rate.
• Upcoding: Billing for a more expensive service than what was actually provided (for example, billing for a complex office visit when a simple one was performed).
• Wrong patient or wrong date: Administrative errors that apply one patient’s charges to another account.
• Services not received: Charges for items or services that were ordered but not actually provided.
• Incorrect insurance information: If the claim was submitted with wrong insurance details, it may be denied or processed incorrectly.

How to compare your EOB and bill

After receiving both your EOB and the provider bill:

1. Match each service line on the bill to the corresponding line on the EOB.
2. Confirm that the allowed amount on the EOB matches the basis for your share of costs on the bill.
3. Check that the services listed on the bill match what you actually received.
4. Verify that your insurer correctly applied your deductible and any prior coinsurance payments.
5. If an in-network provider is billing you more than the “your responsibility” amount shown on the EOB, that may be improper balance billing.

Disputing a charge or a denial

If you find an error, contact the provider’s billing department first. Explain the discrepancy, request a corrected claim be submitted to your insurer if necessary, and keep notes of every conversation including dates and names.

If your insurer denied a claim you believe should be covered, file an internal appeal with your insurer. Your EOB will include the reason for the denial and instructions for appealing. If the internal appeal is unsuccessful, you can request an external review by an independent third party — this right is guaranteed by federal law for most plans.

The Consumer Financial Protection Bureau (CFPB) and your state insurance commissioner’s office can also be resources if a provider or insurer is not responding appropriately to a legitimate dispute.