After any medical visit, you'll receive a document from your insurance company called an Explanation of Benefits, or EOB. It's one of the most important — and most confusing — documents in healthcare. Most people glance at it and throw it away. That's a mistake.
What Is an EOB?
An EOB is a statement from your insurance company explaining how it processed a medical claim. It's not a bill — it's a record of what your insurance was billed, what they agreed to pay, what adjustments were made, and what (if anything) you owe.
You should receive an EOB for every claim your insurance processes, usually by mail or through your insurer's online portal.
Why You Should Read Your EOB Carefully
Your EOB is your first line of defense against billing errors. By comparing your EOB to the actual bill from your provider, you can catch:
- Services billed to insurance that you didn't receive
- Procedures coded incorrectly that cost you more
- Charges your insurance should have covered but didn't
- Errors in how your deductible or out-of-pocket maximum was applied
The Key Columns of an EOB
Every EOB is slightly different, but they all contain the same core information:
Amount Billed
This is what your provider charged — the chargemaster price. It's often much higher than anyone will actually pay. For context on how large this gap can be, see what a Medicare rate actually is.
Contractual Adjustment (or "Not Covered")
The amount your insurance negotiated off the bill based on their contract with the provider. If your provider is in-network, this is the amount written off — you don't owe it and the provider can't bill you for it (called "balance billing," which is often illegal for in-network providers).
Amount Paid by Insurance
What your insurance company actually paid to the provider.
Your Responsibility
What you actually owe. This is the number that matters — your deductible, copay, or coinsurance portion.
Reading a Sample EOB
Here's what a simplified EOB might look like:
| Service | Amount Billed | Contractual Adj | Insurance Paid | You Owe |
|---|---|---|---|---|
| Office visit (99214) | $450 | $230 | $176 | $44 |
| Blood panel (80053) | $320 | $180 | $112 | $28 |
| Total | $770 | $410 | $288 | $72 |
In this example, the provider billed $770. The insurance wrote off $410 based on their contract. The insurance paid $288. You owe $72.
Common EOB Confusion Points
"This is not a bill"
Most EOBs say this prominently, but many patients still try to pay them or confuse them with their actual bill from the provider.
Pending vs. Processed
Sometimes claims are processed in stages. If your EOB shows a claim as "pending," a final EOB will come later.
Out-of-Network Providers
If a provider is out-of-network, the contractual adjustment may be zero or minimal — meaning you could owe the full difference between what insurance paid and what was billed. This is where surprise bills come from. It's especially common after ER visits where you don't choose your providers.
No Surprises Act
Since 2022, the No Surprises Act protects patients from unexpected out-of-network bills in most emergency situations and when you receive care at an in-network facility from an out-of-network provider without your knowledge. If you receive an unexpected out-of-network bill that you think should be covered, you can file a dispute.
How to Use Your EOB to Dispute a Bill
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Match every line — Compare every service on your EOB to every service on your provider bill. They should match.
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Check the coding — Look up any CPT codes you don't recognize. If a code doesn't match the service you received, flag it.
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Verify your cost-sharing — Make sure your deductible, copay, and coinsurance amounts are calculated correctly based on your plan's terms.
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Look for duplicate claims — If you had multiple visits, make sure you haven't been billed twice for the same date of service.
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Save every EOB — Keep EOBs for at least one year, or until you've confirmed all related bills have been paid correctly.
If Something Looks Wrong
- Contact your insurance company first — They can explain how a claim was processed and correct errors on their end.
- Contact your provider's billing department — If the issue is a coding error, they need to submit a corrected claim.
- File an appeal — If your insurance denied a claim you believe should be covered, you have the right to appeal.
For specific guidance on what to say when you call, see our guide to negotiating a hospital bill.
Understanding your EOB is the foundation of managing your healthcare costs. Once you can read it, you'll be better equipped to catch errors before they become collection problems.
If you've already paid a bill that looks wrong, HaggleCare can still help →