Explanation of benefits (EOB) and electronic remittance advice (ERA) are purposely confusing. Here’s how to make sense of them.

You open an explanation of benefits (EOB). You scan the rows of numbers, abbreviations, and codes, trying to figure out what you’re actually getting paid and why the amount never seems to match what you billed. If this feels familiar, you’re not alone. EOBs are often confusing and hard to parse, especially if billing isn’t your background.

This guide walks you through every section of your EOB in plain language, so you can read it with confidence, catch errors before they cost you money, and spend less time second-guessing your billing.

What an EOB actually is (and what it isn’t)

An EOB is a document an insurance company sends to explain what medical treatments were paid for on behalf of a client. It’s not a bill; it’s a breakdown of how the insurance claim was processed and what portion, if any, the client owes.

Insurance companies send EOBs to let you know a claim has been processed. The document covers:

• How much each service costs

• How much the plan will cover

• How much the client may still owe

You might receive your EOB by mail, through your clearinghouse, or via the payer’s online portal. A clearinghouse is a third-party service that submits claims to payers on your behalf and routes payments back to your billing system.

 An electronic remittance advice (ERA) is the digital version of a paper EOB. Unlike paper EOBs, ERAs are routed directly into your billing system or EHR (electronic health record), which can speed up payment posting and reduce manual data entry errors. If your EHR receives ERAs automatically, you may never see a paper EOB at all, since the payment information gets posted without you having to lift a finger.

For the purposes of this article, we’ll use “EOB” to refer to both paper and electronic formats. The information they contain is largely the same.

The sections of your EOB: A line-by-line breakdown

EOBs can vary slightly depending on the insurance company, but they typically follow a similar format. Here’s what you’ll see and what it means.

Client and claim information

Check this section first. It includes:

• The client’s name

• Policyholder information

• Date of service

• Provider name (that’s your practice)

• Current procedural terminology (CPT) codes for services rendered. These are standardized codes used to describe the specific services you provided, like a 60-minute individual therapy session.

If any of those details don’t match your records, it could mean the wrong claim was processed, or that you’re looking at someone else’s EOB.

Amount charged (billed amount)

 This is the amount you billed for the client’s visit: your full rate before any contractual adjustments. If you’re in-network with the payer – meaning you have a signed contract that sets agreed-upon rates – this number is often higher than what you’ll actually be paid. That’s normal. 

Allowed amount (contracted rate)

The allowed amount is what the insurance company deems allowable for the service based on the client’s plan benefits. If you’re in-network, this is the rate you agreed to when you signed your contract. If you’re out-of-network (no contract with that payer), the insurer sets this based on their internal fee schedule.

The difference between what you charged and what was allowed is called the “contractual adjustment” or “discount.” If you’re in-network, you cannot bill your client for this difference.

Amount paid by insurer

 This is what the insurance company is actually sending you. It might be the full allowed amount, or it might be reduced by client responsibility, which may include copay, coinsurance, or deductible.

Client responsibility

 This is the amount the client owes after insurance has been paid. It can include:

• Copay: A fixed amount the client pays per session.

• Coinsurance: A percentage of the allowed amount the client pays.

• Deductible: The amount the client must pay out-of-pocket before insurance kicks in.

 Bill your client the amount listed under “client responsibility” on the EOB – not your original charge, and not the difference between what you billed and what insurance paid. That difference is the contractual adjustment, which you’ve agreed to write off as an in-network provider.

Adjustments and remark codes

These are two different types of codes, and it helps to know what each one does.

Adjustment codes (sometimes called denial codes) explain why a claim was reduced or denied. Common examples include CO-16 (claim lacks information) and CO-197 (precertification or authorization absent). If you see an adjustment code, it’s telling you something went wrong with the claim.

Remark codes are supplemental notes from the payer – usually a short combination of letters and numbers – that provide additional context alongside the adjustment. They might clarify what documentation is missing, suggest what action to take, or explain how a payment was calculated. Check the bottom of the EOB for a plain-language description of each code.

If you see a denial or adjustment you don’t understand, call the payer. Don’t guess.

Common EOB mistakes therapists make (and how to avoid them)

Billing the client the wrong amount

Always bill the client the amount listed under “client responsibility” on the EOB. Billing the difference between your full charge and what insurance paid – rather than the amount shown as client responsibility – is a practice known as balance billing. If you’re in-network, balance billing is a contract violation and can create serious compliance issues.

Ignoring remark codes

Remark codes can explain denials, suggest resubmissions, or point out if documentation is missing. It’s easy to skip over this section, but it often contains important action items. Reading these codes can save you from repeating the same error on future claims.

Not comparing the EOB to your claim

Always match the EOB against the original claim you submitted. If the allowed amount, paid amount, or adjustment codes don’t line up with what you billed, investigate. It could point to a data entry error on your end, an incorrect CPT code, or a payer processing mistake.

Assuming the EOB is always right

Payers make mistakes.  Review the EOB for accuracy, make sure the payment matches the EOB details, and flag any discrepancies with the insurance company. If something looks off, call the payer or check your clearinghouse reports.

When the EOB shows a denial or partial payment

Common reasons for denial include:

• Incorrect client information

• Non-covered services

• Coding errors

• Coverage that ended before the service was provided

• Services rendered before the client was eligible for coverage

One clarification worth knowing: a rejection and a denial are not the same thing. A rejection means your claim didn’t make it into the payer’s system at all – often due to a formatting or eligibility issue – and can usually be fixed and resubmitted quickly. A denial means the claim was received, processed, and declined. The steps below apply to denials specifically.

If your claim is denied, here’s what to do:

1. Review the EOB for the specific reason the claim was rejected or denied.
2. Call the payer if the reason is unclear. Don’t try to interpret denial codes in a vacuum.
3. Correct the error. Most rejections come down to a data entry issue or missing information and are straightforward to fix.
4. Resubmit the claim once errors are corrected.
5. Appeal if needed. If a claim is denied because of medical necessity, you can appeal with additional supporting documentation.

If you want to go deeper on preventing denials before they happen, our free eBook, The Denial-Proof Practice Playbook, walks you through building a billing process that catches errors before they cost you.

How to make EOB review faster and less painful

Set a routine

Pick one day a week to review EOBs, post payments, and follow up on denials. Letting them pile up makes errors harder to catch.

Use your billing software

If you’re enrolled to receive ERAs, the payer sends the remittance directly to your clearinghouse, which routes it into your account. Most mental health EHRs and practice management systems can auto-post payments from ERAs, flag discrepancies, and track denial trends over time. If yours can’t, it may be time to switch.

Keep a cheat sheet

Create a simple reference document with your contracted rates for each payer and the CPT codes you use most often. When you review an EOB, you’ll know immediately if the allowed amount is correct.

Know when to escalate

If the same payer consistently underpays, pays late, or denies claims for unclear reasons, document the pattern and escalate. Many underpayments are fixable billing errors, not policy issues.

Final thoughts

EOBs are not designed to be easy to read. They’re written for payer systems, not clinicians. But once you know what each section means and how the numbers connect, they become a tool, not a mystery.

You don’t need to be a billing expert to read your EOB with confidence. You just need to know where to look, what to check, and when to ask questions. With practice, this becomes routine. And that means fewer surprises, fewer errors, and more time doing the work that matters.

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