You get a piece of mail from your health insurance company. It says "EXPLANATION OF BENEFITS" or "This Is Not a Bill." It's dense with columns and numbers. Most people throw it away. That's a mistake — here's why this document matters and how to read it.
What Is an EOB?
An Explanation of Benefits is a statement from your health insurance company showing:
- What medical services were billed
- What your insurance allowed (vs. what was billed)
- What your insurance paid
- What you're responsible for
An EOB is not a bill — but it tells you exactly what bill is coming, or confirms whether the bill you received is accurate. If a provider bills you more than the EOB says you owe, that's a potential billing error or balance billing violation.
The Key Columns Every EOB Has
1. Service Description / Procedure Code
What service was rendered. Listed as a CPT code (like 99213 for an office visit) or a description. Cross-reference this with the date of your appointment to make sure it matches.
2. Amount Billed (Submitted Charge)
What the provider originally charged. This is almost never what you or insurance actually pays — it's the sticker price before negotiated discounts.
3. Contractual Adjustment / Discount
The reduction applied because your provider is in-network. In-network providers agree to accept lower rates. This discount is the negotiated savings. You don't owe this amount.
4. Amount Allowed (Allowed Charge)
The "allowed" or "eligible" charge — the amount your insurance agreed to pay after applying the network discount. This is the number that matters.
5. Plan Paid
How much your insurance company actually paid. This goes directly to the provider.
6. Your Responsibility
What you owe the provider. This is the combination of:
- Deductible: What you pay before insurance starts covering anything
- Copay: A fixed amount per visit
- Coinsurance: Your percentage after the deductible is met (e.g., 20% of the allowed charge)
- Non-covered amount: Services your plan doesn't cover at all
7. Deductible Applied
How much of the allowed charge goes toward your annual deductible. Once your deductible is met for the year, you stop seeing this number.
Example: Reading a Real EOB Row
| Column | Amount | | ----------------------- | ------- | | Amount Billed | $450 | | Contractual Adjustment | -$180 | | Amount Allowed | $270 | | Plan Paid | $216 | | Deductible Applied | $0 | | Coinsurance (20%) | $54 | | Your Responsibility | $54 |
The provider billed $450. You'll owe $54. The bill that arrives from the provider should say $54 — not $450.
The Most Common EOB Errors
1. Wrong patient or date of service
Confirm every line matches a service you actually received. Billing errors and fraud both exist.
2. Service coded incorrectly
A procedure billed under the wrong CPT code can result in denial or higher patient cost. Compare the code to the service you actually received.
3. In-network provider billed as out-of-network
If you saw an in-network provider but the EOB shows out-of-network rates (higher cost to you), the provider may have forgotten to update their network status or billed under the wrong NPI.
4. Denied as "not medically necessary"
This means insurance didn't cover the service. You can appeal — especially if your doctor ordered it. You typically have 180 days from the denial to appeal.
5. Duplicate billing
Two identical service lines for the same date. Dispute this with the provider directly.
What to Do If the Provider's Bill Doesn't Match the EOB
- Call the provider's billing department
- Give them the EOB and your account number
- Ask them to resubmit the corrected amount
- If they refuse, file a complaint with your state insurance commissioner
Providers are not allowed to charge in-network patients more than the "patient responsibility" shown on the EOB (this is called balance billing and is illegal for in-network services).
When to Keep EOBs
Keep every EOB for the same year until:
- Your annual deductible tracking is complete
- Your taxes are filed (medical expense deductions require documentation)
- You've confirmed every provider bill matches the corresponding EOB
Got an EOB that's confusing you? PaperLens reads insurance documents and translates every line into plain English — instantly. Scan your EOB →