The short answer
An Explanation of Benefits (EOB) is a statement your health insurer sends after a provider submits a claim. It tells you: what the provider charged, what your plan allowed, what the insurer paid, and what (if anything) you owe. It is not a bill — don't pay the amount shown until you get a separate bill from the provider.
The six fields that matter
- Billed amount — what the provider charged. Often inflated relative to what insurers actually pay.
- Plan allowed amount — the negotiated rate between your insurer and the provider. For in-network providers, this is the contract price.
- Not covered / plan discount — the difference between the billed amount and the allowed amount. For in-network providers, this is written off. For out-of-network, it may become your responsibility (balance billing — see our balance billing guide).
- Insurer paid — how much the insurer sent to the provider.
- Your responsibility — the amount the insurer says you owe. This is what the provider should bill you.
- CARC / RARC codes — Claim Adjustment Reason Codes explain why a portion wasn't paid. CARC 45 means the charge exceeded the allowed amount; CARC 96 is “non-covered”; CARC 197 is “precertification missing”; and so on. These codes are your dispute ammunition.
The reconciliation move
Put the EOB and the provider's bill side by side. The “amount due” on the bill should equal the “your responsibility” line on the EOB. If the bill is higher, the provider is charging you for an amount the insurer said you don't owe. That's the beginning of a dispute.
Red flags on an EOB
- A large “not covered” amount with a vague denial code — push back; demand the full reason.
- A claim denied for “not medically necessary” — see our appeal guide.
- An in-network provider with a “patient responsibility” higher than your plan's normal copay or coinsurance — possible coding or processing error.
- Services you don't remember receiving — possible identity theft or provider misbilling.
If you're uninsured, you don't get an EOB
No insurer, no EOB. Instead, for scheduled care, you're entitled to a Good Faith Estimate before the service happens, and you can dispute the final bill if it exceeds the estimate by more than $400.
Fix My Bill reads your EOB alongside your itemized bill and flags the mismatches automatically. Decision-support only — always verify with your insurer before acting.