> ## Documentation Index > Fetch the complete documentation index at: https://dso.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; plus how downgrades and benefit limitations read on a dental remittance. **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 updated periodically. This page covers common dental-billing scenarios rather than the complete code set. Use [x12.org/codes/claim-adjustment-reason-codes](https://x12.org/codes/claim-adjustment-reason-codes) for current definitions and codes not listed here. ## Interpret the CARC and group code together A CARC should be read with its group code: * **CO-45** generally reports a contractual fee adjustment. * **PR-45** reports the fee-schedule difference as patient responsibility and warrants review against the contract and plan. * **CO-197** classifies a missing authorization adjustment as the provider's contractual obligation. * **PR-197** classifies it as patient responsibility; confirm the plan facts, contract, and notice rules before billing. Always read both. See [Group codes](/reference/edi/group-codes). ## Reading dental remittances: there is no "downgrade code" Downgrades under an alternate-benefit or LEAT provision, frequency limits, and exhausted annual maximums do not have dedicated CARCs. They use ordinary group and reason codes. A downgraded composite may appear as a paid line whose allowed amount reflects the amalgam alternative, while a frequency-limited or over-maximum service may appear as a noncovered or benefit-design adjustment. Do not classify a dental remittance as a denial, downgrade, or benefit limitation from the CARC alone. Read the group code, allowed amount, contracted fee, plan terms, and any RARC together. Confirm that the payer applied the plan correctly before deciding whether to post, bill the patient, correct the claim, or appeal. See [Denials vs downgrades](/concepts/payments/denials-vs-downgrades) and the [denial code playbook](/reference/edi/denial-code-playbook). ## 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 | | 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, including whether a leased-network rate was applied; see [Network leasing](/concepts/payments/network-leasing) | | 253 | Sequestration, federal payment reduction | CO | Medicare only; rare in dental; 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** because CARC 16 alone does not identify the missing item. | | 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; DHMO plans commonly require specialist referrals | ## 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 A **predetermination** is voluntary, so its absence alone does not trigger these codes. A **preauthorization** is required before treatment by some plans, mainly Medicaid programs and DHMOs, and the codes below may report a missing 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; watch ortho continuation claims | | 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 with clinical documentation | ## Necessity and coverage | CARC | Meaning | Typical group | Action | | ------- | ------------------------------------------------------------------------------------------------- | ------------- | -------------------------------------------------------------------------------------------------------------------------------------- | | **50** | Not deemed a necessity by the payer | CO | Appeal with radiographs, charting, narrative, and the payer's own coverage criteria | | **96** | **Non-covered charge(s)** | CO/PR | Read the RARC. Benefit design; cosmetic exclusions, adult ortho, implant exclusions. 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 the payer's bundling policy; appeal with documentation if the service was genuinely separate. | | 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; for dependents, the birthday rule; 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 | Service location issue | | 109 | Claim not covered by this payer/contractor, send to the correct entity | CO/OA | Rebill the correct payer; often the Medicaid dental benefit administrator rather than the state | | **B7** | This provider was not certified/eligible to be paid for this procedure on this date | CO | **Effective date problem**; very common for new associates and freshly acquired offices | ## Adjustments and recoveries | CARC | Meaning | Typical group | Action | | ------- | -------------------------------------------------------------------------- | ------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------- | | **252** | An attachment/other documentation is required | CO | Submit the documentation; radiographs, perio charting, narrative; through the payer's channel; see [Dental attachments](/reference/edi/dental-attachments) | | 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 | ## Adjustments that may be expected Train billers to recognize these adjustments so they do not enter an appeal queue automatically: | CARC | Why it may be expected | | ------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | **CO-45** | The standard contractual write-off and, in dental, commonly the PPO write-off line. Verify it against the fee schedule. | | **PR-1, PR-2, PR-3** | Normal patient cost-sharing. Bill the patient. | | **CO-97** | Bundling, per the payer's policy. Often correct. | | **CO-96 / CO-204** | Benefit design. The service isn't covered; that isn't a claim defect. | | **Downgrades and limitations** | Alternate-benefit pricing, frequency limits, and exhausted maximums arrive on ordinary codes. If the payer applied the plan correctly, route the amount according to the group code rather than appealing automatically. | ## Coding note CARCs are X12-maintained. CDT is maintained and licensed by the ADA (and CPT by the AMA); this page references procedure-code concepts only illustratively. Do not reproduce licensed code sets wholesale. See [Code sets overview](/reference/edi/code-sets-overview).