CARC / RARC reference

The most common Claim Adjustment Reason Codes (CARC) and Remittance Advice Remark Codes (RARC) you will see, with the platform's first- recommended action.

CARC by group

CO — Contractual

Code	Meaning	Action
CO-1	Deductible	Routes PR-1 to patient AR; auto.
CO-2	Coinsurance	Routes PR-2 to patient AR; auto.
CO-3	Copay	Routes PR-3 to patient AR; auto.
CO-4	Procedure code inconsistent with modifier	Auto-correct: CO4ModifierHandler.
CO-11	Diagnosis inconsistent with procedure	Manual; usually code-set issue.
CO-15	Authorization missing or invalid	Manual rebill with auth, or appeal.
CO-16	Claim/service lacks information	Auto-correct: Co16MissingInfoHandler.
CO-18	Duplicate claim/service	Auto-detect; mark via claim_relationship.
CO-22	Care covered by another payer per COB	Check member's COB ladder.
CO-29	Time limit for filing has expired	Auto-correct timely-filing exception, or write off.
CO-45	Charge exceeds fee schedule	Informational; normal contractual write-off.
CO-50	Non-covered services	Manual; sometimes appealable with documentation.
CO-95	Plan procedures not followed	Manual; usually procedure / process issue.
CO-96	Non-covered charges	Same as CO-50.
CO-97	Bundled services	Auto-correct: re-coding.
CO-109	Claim not covered by this payer	COB question.
CO-167	Diagnosis(es) not covered	Manual; usually requires medical-necessity letter.
CO-197	Precert/authorization absent	Auto-correct: attach auth + rebill.
CO-204	Service not covered under benefit plan	Manual review.
CO-256	Service not payable per managed-care contract	Manual; payer policy.

PR — Patient responsibility

Code	Meaning
PR-1	Deductible.
PR-2	Coinsurance.
PR-3	Copay.
PR-22	Care may be covered by another payer (patient-side).
PR-31	Patient cannot be identified.
PR-49	Routine exam — non-covered patient-side.
PR-204	Patient-side non-covered.
PR-227	Information requested from patient/insured was missing.

OA — Other adjustment

Code	Meaning
OA-23	Impact of prior payer adjudication.
OA-24	Charges covered under capitation agreement / managed-care plan.
OA-94	Processed in excess of charges (rare).
OA-100	Payment made to patient/insured/responsible party.
OA-109	Not covered by this payer; OA flavor of CO-109.

PI — Payer-initiated

Code	Meaning
PI-50	Not deemed medically necessary.
PI-204	Service not covered under benefit plan.
PI-256	Not payable per managed-care contract.

CR — Reversal

CR rows reverse a prior CAS row (e.g. correcting a denial). They must reference the prior to net cleanly.

RARC

M-prefixed (most common)

Code	Meaning
M16	Alert: see attached.
M51	Missing/incomplete/invalid procedure code.
M76	Missing/incomplete/invalid diagnosis or condition.
M77	Missing/incomplete/invalid place of service.
M86	Service denied because pmt already made.
M127	Missing patient med. record.

MA-prefixed

Code	Meaning
MA13	Subject to penalty for not informing the patient.
MA15	Late claim adjustment.
MA67	Correction to a prior claim.
MA92	Same/similar service in lookback.

N-prefixed

Code	Meaning
N4	Missing prior payer EOB.
N122	Add-on code cannot be billed by itself.
N130	Member's plan benefits don't cover this service.
N640	Exceeds LCD or MUE.

Reading multiple codes together

Common combinations and their joint reading:

CARC + RARC	Joint read
CO-16 + M51	Missing/invalid procedure code.
CO-16 + MA67	Need correction; usually frequency-7 path.
CO-16 + N4	Missing prior-payer EOB; check COB chain.
CO-167 + MA13	Diagnosis not covered + you should have informed patient.
PR-1 + MA15	Patient deductible + late submission.
CO-29 + MA15	Timely filing — explicit.
CO-50 + N130	Non-covered + plan doesn't cover.

Codes the platform's auto-correction handles

CARC	Handler
CO-4	CO4ModifierHandler
CO-16	Co16MissingInfoHandler
CO-18	Co18DuplicateHandler
CO-29	Co29TimelyFilingHandler
CO-97	Co97BundlingHandler
CO-197	Co197AuthHandler
PR-1 / 2 / 3	PrPatientHandler

See 5.3 — Auto-correction console for handler details.

Where to find the canonical lists

The full ASC X12 reference is published at the X12 / WPC site. The platform's reference excerpt (the tooltip you see) is refreshed periodically by admin. If you encounter a code that isn't in this reference, the chip will say unknown; flag for admin to refresh.