Denial Code Decoder
Every remittance advice carries a claim adjustment reason code (CARC) and, often, a remark code (RARC) explaining what happened to a line item. Browse the codes below for a plain-language explanation, common causes, and the general next steps therapists take.
These codes are maintained by the X12 committee and updated periodically — always confirm the current meaning of a code against the official code lists and your own remittance.
Claim Adjustment Reason Codes (CARC)
Deductible amount
The claim was processed, but this portion was applied to the patient's yearly deductible — so the plan paid $0 on it until the deductible is met.
Coinsurance amount
The plan allowed the service and paid its share; this is the percentage the patient owes (e.g. 20-40% of the allowed amount) after the deductible.
Co-payment amount
A flat per-visit amount the patient owes under their plan.
Procedure/modifier mismatch
The payer thinks the CPT code and its modifier don't match — or that a modifier the code needed wasn't there.
Diagnosis inconsistent with procedure
The payer's edits say the ICD-10 diagnosis doesn't justify the CPT service.
Claim lacks information / submission error
A catch-all 'something's missing or wrong' code.
Exact duplicate claim
The payer already has this exact claim on file, so the second one was set aside.
May be covered by another payer (COB)
The payer thinks someone else is primary — another plan, a spouse's plan, Medicare — and wants that billed first.
Timely filing limit expired
The claim arrived after the payer's timely-filing window (often 90-365 days from the date of service).
Not deemed a medical necessity
The payer decided the service wasn't medically necessary as billed.
Benefit included in another service (bundling)
The payer considers this service bundled into another one it already paid — so it won't pay separately.
Not covered by this payer
You billed the wrong payer or the wrong plan/product.
Benefit maximum reached
The patient hit a plan limit — a visit cap, dollar cap, or annual maximum for this kind of service.
Precertification/authorization absent
The plan required prior authorization for this service and it wasn't on file.
Additional documentation required
The payer paused the claim pending paperwork — notes, an itemized statement, or an attachment.
Educational information only
This page is general educational information, not legal, billing, or medical advice, and not a determination about any specific claim. Denial codes are maintained by the X12 committee and updated periodically. Always verify code meanings, benefits, and requirements directly with the payer and against your own records.
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