> ## Documentation Index > Fetch the complete documentation index at: https://mso.getlemma.com/llms.txt > Use this file to discover all available pages before exploring further. # CARC codes (Claim Adjustment Reason Codes) > The working set of commonly encountered CARCs with plain-English meaning, typical root cause, and action. **Claim Adjustment Reason Codes (CARCs)** explain why a claim or service line was paid differently than billed. They appear in the `CAS` segment of the 835, always paired with a [group code](/reference/edi/group-codes). CARCs are maintained by **X12** and the list is updated periodically. This page covers the working set you will encounter most; it is not the complete list. The authoritative source is [x12.org/codes/claim-adjustment-reason-codes](https://x12.org/codes/claim-adjustment-reason-codes) — check it for codes not listed here and for current definitions. ## Read the pair, not the code A CARC alone is incomplete. **Group code + CARC** is the actionable unit: * **CO-45**, contractual write-off. Normal. * **PR-45**, would mean the patient owes the fee-schedule difference. Almost never correct; investigate. * **CO-197**, you failed to get authorization. Cannot bill the patient. * **PR-197**, the patient failed to obtain a required authorization. Rare, and depends on the plan. Always read both. See [Group codes](/reference/edi/group-codes). ## Patient responsibility | CARC | Meaning | Typical group | Action | | ----- | ---------------------------------- | ------------- | ---------------------- | | **1** | Deductible amount | PR | Bill the patient | | **2** | Coinsurance amount | PR | Bill the patient | | **3** | Copayment amount | PR | Bill the patient | | 66 | Blood deductible | PR | Bill the patient | | 142 | Monthly Medicaid patient liability | PR | Bill per program rules | ## Contractual adjustments | CARC | Meaning | Typical group | Action | | ------ | ----------------------------------------------------------------------------- | ------------- | ---------------------------------------------------------------------- | | **45** | **Charge exceeds fee schedule / maximum allowable or contracted arrangement** | CO | **Write off.** The most common adjustment in healthcare. Not a denial. | | 59 | Processed based on multiple or concurrent procedure rules | CO | Verify against contract; often correct | | 94 | Processed in excess of charges | CO/OA | Review, usually a posting or submission issue | | 131 | Claim-specific negotiated discount | CO | Verify against contract | | 253 | Sequestration, federal payment reduction | CO | Medicare; write off | ## Missing or invalid information | CARC | Meaning | Typical group | Action | | ------ | -------------------------------------------------------------------------------- | ------------- | ----------------------------------------------------------------------------------------- | | **16** | **Claim/service lacks information or has submission/billing error** | CO | **Read the RARC**, CARC 16 alone is a scavenger hunt. The RARC identifies what's missing. | | 4 | Procedure code inconsistent with the modifier, or a required modifier is missing | CO | Correct the modifier and resubmit | | **8** | **Procedure inconsistent with the provider type or specialty** | CO | Usually a **taxonomy mismatch** or a credentialing issue | | 11 | Diagnosis inconsistent with the procedure | CO | Review coding; correct or appeal with documentation | | 12 | Diagnosis inconsistent with the provider type | CO | Review; may be a taxonomy issue | | 125 | Submission/billing error | CO | Read the RARC | | 206 | NPI missing or invalid | CO | Enrollment or claim data problem | | 288 | Referral absent | CO | Obtain and resubmit | ## Eligibility | CARC | Meaning | Typical group | Action | | ------ | ------------------------------------------------------------- | ------------- | ----------------------------------------------------- | | **26** | Expenses incurred prior to coverage | CO/PR | Verify coverage dates; may be patient responsibility | | **27** | Expenses incurred after coverage terminated | CO/PR | Verify; rebill correct payer or bill the patient | | **31** | Patient cannot be identified as our insured | CO | Verify member ID and demographics; often a data error | | 32 | Our records indicate the patient is not an eligible dependent | CO | Verify relationship and coverage | | 33 | Insured has no dependent coverage | CO | Verify plan | | 177 | Patient has not met the required eligibility requirements | CO | Verify | ## Authorization | CARC | Meaning | Typical group | Action | | ------- | -------------------------------------------------------------------------- | ------------- | ----------------------------------------------------------------------------------------- | | **197** | **Precertification / authorization / notification / pre-treatment absent** | **CO** | **Cannot bill the patient.** Corrected claim with the auth number, retro-auth, or appeal. | | **198** | Precertification / authorization exceeded | CO | Units or visits beyond what was authorized | | 15 | The authorization number is missing, invalid, or does not apply | CO | Verify the auth matches the service billed | | 39 | Services denied at the time authorization was requested | CO | Appeal on medical necessity | ## Medical necessity and coverage | CARC | Meaning | Typical group | Action | | ------- | ------------------------------------------------------------------------------------------------- | ------------- | ---------------------------------------------------------------------------------------------- | | **50** | Not deemed a medical necessity by the payer | CO | Appeal with documentation and the applicable coverage policy | | **96** | **Non-covered charge(s)** | CO/PR | Read the RARC. Benefit design, not an error. May be patient responsibility with proper notice. | | **97** | The benefit for this service is included in the allowance for another service already adjudicated | CO | **Bundling.** Verify NCCI edits; modifier if clinically justified. | | 151 | Payer determines the information submitted does not support this many services | CO | Documentation or units issue | | 167 | Diagnosis is not covered | CO | Verify coverage policy | | **204** | Service not covered under the patient's current benefit plan | PR/CO | Benefit design | ## Coordination of benefits | CARC | Meaning | Typical group | Action | | ------ | ------------------------------------------------------------------------------- | ------------- | --------------------------------------- | | **22** | This care may be covered by another payer per coordination of benefits | CO/OA | Determine payer order; bill the primary | | **23** | The impact of prior payer(s) adjudication including payments and/or adjustments | OA | Informational on secondary claims | | 24 | Charges are covered under a capitation agreement or managed care plan | CO | Verify arrangement | ## Timely filing and duplicates | CARC | Meaning | Typical group | Action | | ------ | ----------------------------------------- | ------------- | --------------------------------------------------------------------- | | **29** | **The time limit for filing has expired** | CO | Appeal with clearinghouse acceptance report proving timely submission | | **18** | Exact duplicate claim/service | CO | You resubmitted instead of correcting. Use frequency code 7. | ## Provider and enrollment | CARC | Meaning | Typical group | Action | | ------- | ----------------------------------------------------------------------------------- | ------------- | ----------------------------------------------------- | | **185** | The rendering provider is not eligible to perform the service billed | CO | Credentialing or scope issue | | 170 | Payment denied when performed by this type of provider | CO | Taxonomy or provider type | | 171 | Payment denied when performed in this type of facility | CO | Place of service | | 109 | Claim not covered by this payer/contractor, send to the correct entity | CO/OA | Rebill the correct payer or MAC | | **B7** | This provider was not certified/eligible to be paid for this procedure on this date | CO | **Effective date problem**, very common for new hires | ## Adjustments and recoveries | CARC | Meaning | Typical group | Action | | ------- | -------------------------------------------------------------------------- | ------------- | --------------------------------- | | **252** | An attachment/other documentation is required | CO | Submit the documentation | | 100 | Payment made to patient/insured/responsible party | OA | Recover from the patient | | 226 | Information requested from the billing/rendering provider was not provided | CO | Respond and resubmit | | 227 | Information requested from the patient was not provided | PR/CO | Patient must respond to the payer | ## The ones that aren't problems Worth training billers on explicitly, because they generate wasted work: | CARC | Why it's not an error | | -------------------- | --------------------------------------------------------------------- | | **CO-45** | The standard contractual write-off. The system worked. | | **PR-1, PR-2, PR-3** | Normal patient cost-sharing. Bill the patient. | | **CO-253** | Medicare sequestration, a statutory reduction. | | **CO-97** | Bundling. Often correct, per NCCI. | | **CO-96 / CO-204** | Benefit design. The service isn't covered; that isn't a claim defect. | ## CPT/coding note CPT is maintained and licensed by the AMA. This page describes CARCs, which are X12-maintained, and references CPT codes only illustratively. Do not reproduce licensed code sets wholesale. See [Code sets overview](/reference/edi/code-sets-overview). ## Related topics - [Claim denials, explained](/concepts/payments/claim-denials.md) - [The 835: how payers answer](/concepts/payments/understanding-835s.md) - [Work the denial queue](/guides/billing/work-the-denial-queue.md) - [File appeals](/guides/billing/file-appeals.md) - [Group codes (CO, PR, OA, PI)](/reference/edi/group-codes.md) - [RARC codes (Remittance Advice Remark Codes)](/reference/edi/rarc-codes.md) - [Denial code playbook](/reference/edi/denial-code-playbook.md)