Health insurance denial codes, explained
The code on your Explanation of Benefits (EOB) tells you exactly why a claim was denied or adjusted — once you know how to read it. These plain-English explanations cover the most common Claim Adjustment Reason Codes (CARCs), what they really mean, and whether you can appeal.
Contractual Obligation — an adjustment tied to the contract between the insurer and the provider. You usually cannot be billed for a CO amount.
Patient Responsibility — an amount the plan says may be billed to you, the patient.
Precertification / prior authorization not obtained
The plan required precertification, authorization, or advance notification for this service and it wasn't on file.
What it means →Not covered under the current benefit plan
This service, drug, or equipment isn't covered under your current plan's benefits.
What it means →Not deemed a medical necessity
The payer decided the service wasn't medically necessary under its criteria.
What it means →Non-covered charge(s)
The charge isn't covered — the paired remark code explains the specific reason.
What it means →Claim lacks information or has a submission error
The claim is missing information or has a billing error and can't be processed as submitted.
What it means →Charge exceeds the fee schedule or allowed amount
The billed charge is higher than the plan's contracted or allowed amount; the excess is written off.
What it means →Payment bundled into another service
This service is considered part of another procedure that was already paid, so it isn't paid separately.
What it means →Duplicate claim or service
The payer flagged this claim as an exact duplicate of one already submitted.
What it means →Time limit for filing has expired
The claim was submitted after the plan's timely-filing deadline.
What it means →Not covered by this payer — send to the correct payer
This claim should go to a different payer or contractor, not this one.
What it means →May be covered by another payer (coordination of benefits)
The plan thinks another insurer should pay first under coordination of benefits.
What it means →Deductible amount
The amount applied to your plan deductible, which you owe before coverage kicks in.
What it means →Coinsurance amount
Your coinsurance share of the allowed amount after the deductible.
What it means →Copayment amount
The fixed copay you owe for this visit or service.
What it means →Expenses incurred after coverage terminated
The plan says the service happened after your coverage ended.
What it means →Procedure code inconsistent with the modifier (or a modifier is missing)
The procedure code and modifier don't match, or a required modifier wasn't included.
What it means →Diagnosis inconsistent with the procedure
The diagnosis code billed doesn't support the procedure that was performed.
What it means →Authorization number missing or invalid
The authorization number is missing, invalid, or doesn't apply to this claim.
What it means →Information doesn't support this many services
The payer says the documentation doesn't justify the number or frequency of services billed.
What it means →This diagnosis is not covered
The plan doesn't cover services for the diagnosis billed.
What it means →Provider not eligible or certified for this service on this date
The provider wasn't certified, enrolled, or eligible to be paid for this service on the date of service.
What it means →Benefit maximum has been reached
You've hit the plan's benefit maximum for this service, period, or occurrence.
What it means →Routine or preventive exam (non-covered)
The service was treated as a routine or preventive exam the plan doesn't cover this way.
What it means →Additional documentation required
The payer needs more documentation before it can process the claim.
What it means →Got a denial code? Fight it.
Our free generator builds a tailored appeal letter, an escalation letter, and a phone script — entirely in your browser, with nothing stored or uploaded.