How to Read an Explanation of Benefits (EOB)

An EOB)" class="auto-link">Explanation of Benefits (EOB) is not a bill — but it contains information that can save you significant money if you know how to read it. It is a statement from your insurance company explaining how a claim was processed: what was billed, what the plan allowed, what it paid, and what you owe. It is also where denial reasons and appeal deadlines appear. Here is a complete walkthrough of every section of an EOB and what each field means.

What an EOB Is (and Is Not)

First, the most important clarification: an EOB is a summary of claim processing, not a bill. You do not need to pay the insurance company when you receive an EOB. You may eventually receive a separate bill from your provider — and the EOB helps you verify that bill is accurate.

EOBs arrive by mail or (if you have paperless settings) through your insurer's online portal. Keep every EOB you receive. They are your official record of how your insurance responded to each claim.

The Header Section

The top of every EOB contains identifying information:

• Your name and member ID: Verify these match your information exactly. Errors here can cause claims to be misapplied.
• Group number: Identifies your employer plan or individual plan
• Date of the EOB: The date the insurer generated this document — not necessarily the date of service
• Claim number: The unique identifier for this claim. Always reference this number when contacting the insurer.
• Provider name: The healthcare provider who submitted the claim
• Date of service: When you received care

The Claim Detail Section: The Most Important Part

The claim detail section is where the financial breakdown appears. It lists each service billed as a separate line item. Here is what each column means:

Billed Amount (or "Provider Charged") What the provider originally billed your insurance. This is almost never what you will actually owe. Providers bill at their chargemaster rates, which are almost always much higher than the negotiated rate.

Allowed Amount (or "Plan Allowed" or "Negotiated Rate") The maximum amount your insurer has agreed to pay for this service based on its contract with in-network providers (or its allowed amount calculation for out-of-network). The difference between the billed amount and the allowed amount is a contractual write-off — neither you nor the insurer pays this. If you are in-network, the provider cannot bill you this difference.

Example:

• Billed amount: $1,200
• Allowed amount: $450
• Write-off: $750 (you owe nothing on this portion)

Not Covered (or "Plan Deducted — Non-Covered") Any portion the plan excludes entirely. If there is an amount here, the denial code in the next section explains why.

Applied to Deductible The portion of the allowed amount credited toward your annual deductible. You owe this to the provider.

Copay / Coinsurance Your fixed copay (if applicable) or your percentage share of the allowed amount after the deductible is met. You owe this to the provider.

Plan Paid The amount the insurer paid directly to the provider (or to you, if you paid out of pocket).

Your Responsibility The total amount you owe the provider: deductible + copay/coinsurance. This is what should appear on your provider's bill. If your provider bills you more than this amount, there may be a billing error.

The Denial / Adjustment Codes Section

When a service is denied or partially paid, the EOB will list adjustment reason codes. These typically follow the CARC/RARC coding system:

CARC codes (Claim Adjustment Reason Codes): Explain why the payment was adjusted. Common examples:

• CO-4: Service not authorized
• CO-11: Diagnosis inconsistent with procedure
• CO-50: Non-covered service
• PR-1: Deductible not met
• CO-97: Service included in previously adjudicated claim

RARC codes (Remittance Advice Remark Codes): Supplementary information clarifying the CARC. Common examples:

• N130: Consult plan benefit documents
• N382: Missing authorization number

Every code that appears on your EOB has a standard definition. Look up unfamiliar codes at the Washington Publishing Company's code set directory or at cms.gov.

The Appeals Section

By law, your EOB must include information about your right to appeal and the deadline to file. Look for a section titled "Your Appeal Rights" or "Dispute Resolution." Key information here:

• Appeal deadline: Typically 180 days from the EOB date for ACA-regulated plans
• Address to send appeals: The specific address or fax number for the appeals department
• External Independent Review: Complete Guide" class="auto-link">External review information: Your right to request independent external review after internal appeal

Do not miss this deadline. Mark it on your calendar the day you receive the EOB.

Checking for Billing Errors

Now that you can read an EOB, use it to check your provider's bill:

1. Match line items: Each service on your provider's bill should match a line item on your EOB. If your bill includes charges not on the EOB, the provider may not have submitted them to insurance — call them.

2. Compare "Your Responsibility" with the provider's bill: Your provider should only charge you the amount shown under "Your Responsibility" on the EOB. If they are charging more, either they billed for something insurance did not cover, or there is a billing error.

3. Request an itemized bill: If any charge seems incorrect, ask the provider for an itemized statement listing every service, code, and date. This is your right, and it reveals errors that aggregate bills obscure.

4. Verify your cost-sharing was calculated correctly: If your deductible tracker shows you should have met your deductible before this service, but the EOB still shows "applied to deductible," call your insurer and ask for a deductible accumulation report.

How to Use Your EOB to File an Appeal

Your EOB is the foundation of any appeal. When writing an appeal:

• Reference the claim number from the EOB
• Quote the specific denial code from the EOB
• Use the EOB date as the starting point for your 180-day appeal window
• Send your appeal to the specific address or fax listed in the EOB's appeals section

Reading your EOB takes 10 minutes. Understanding it can recover hundreds or thousands of dollars. Make it a habit every time a new one arrives.

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Related Reading:

• How to Write an Insurance Appeal Letter
• What Is Medical Necessity?
• Internal vs External Insurance Appeal