Behavioral Health Billing
Denial Code Glossary
The CARC and RARC codes behavioral health and SUD treatment centers see most on their EOBs and ERAs, in plain English. What each one means, why it shows up, and how to fix and prevent it.
New here? Start with why behavioral health denials keep rising and how to read an EOB / ERA.
CARC — Claim Adjustment Reason Codes
CO-4Contractual adjustment
Procedure code inconsistent with modifier / missing modifier
The procedure code and its modifier do not agree, or a required modifier is missing, so the payer will not adjudicate the line as billed.
CO-16Contractual adjustment
Claim lacks information or has a submission error
The claim is missing information or contains a submission error, so the payer cannot adjudicate it until the specific problem is corrected.
CO-18Contractual adjustment
Exact duplicate claim or service
The payer identifies this claim or line as an exact duplicate of one already received, so it will not pay it a second time.
CO-22Contractual adjustment
May be covered by another payer per coordination of benefits
The payer believes another plan is primary and should pay first, so it will not process the claim until coordination of benefits is resolved.
CO-29Contractual adjustment
Time limit for filing has expired
The claim was submitted after the payer's timely filing deadline, so it is denied for late filing.
CO-45Contractual adjustment
Charge exceeds fee schedule or contracted amount
Your billed charge is higher than the payer's fee schedule or your contracted rate, and the excess is a required contractual write-off.
CO-50Contractual adjustment
Not deemed a medical necessity
The payer determined the service was not medically necessary as billed, so it will not pay it under the contract.
CO-96Contractual adjustment
Non-covered charges
The service is not a covered benefit as billed, and the charge is treated as a contractual adjustment rather than patient responsibility.
CO-97Contractual adjustment
Benefit included in another service already adjudicated
The payment for this service is bundled into another service that was already paid, so it is not separately reimbursable.
CO-109Contractual adjustment
Not covered by this payer or contractor, send to correct payer
This claim is not the responsibility of the payer you billed, and it should be sent to the correct payer or contractor.
CO-197Contractual adjustment
Precertification, authorization, or notification absent
The service required precertification or authorization that was not obtained, so the payer denies it as a contractual provider responsibility.
PR-1Patient responsibility
Deductible amount
The amount is applied to the patient's deductible and is billable to the patient.
PR-2Patient responsibility
Coinsurance amount
The amount is the patient's coinsurance share of the allowed amount and is billable to the patient.
PR-3Patient responsibility
Copayment amount
The amount is the patient's fixed copay for the service and is billable to the patient.
PR-96Patient responsibility
Non-covered charge, patient responsibility
The service is non-covered and, unlike CO-96, the balance is assigned to the patient rather than written off.
PR-204Patient responsibility
Not covered under the patient's current plan
The service, equipment, or drug is not covered under the patient's current benefit plan, and the balance is assigned to the patient.
RARC — Remittance Advice Remark Codes
MA130Informational
Claim contains incomplete or invalid information
A remark stating the claim has incomplete or invalid information and often that it was rejected as unprocessable, so no appeal rights attach until it is corrected and resubmitted.
N130Informational
Refer to plan benefit documents for coverage details
A remark directing you to the plan's benefit documents to determine coverage, limitations, or exclusions for the service.