Instantly find explanations, causes, and resolution steps for every Claim Adjustment Reason Code (CARC) and Remark Code.
Claim Adjustment Reason Codes (CARC) explain why a payment differs from what was billed. Every 835 ERA and EOB uses these standardized codes.
Search any code or keyword above. Each page includes the full description, common causes, resolution steps, and appeal guidance.
Each denial code page also links to a dedicated Remark Code page — optimized for providers searching for ERA remark code context.
Most denials are reversible. Our guides walk you through the correct steps to correct, resubmit, or formally appeal each denial type.
| Code | Description | View |
|---|---|---|
| 334 | invalid age Invalid age for service provided | Details → |
| 335 | Please note the payee number. You must use this number when billing for pain clinic s… | Details → |
| 335 | invalid sex Invalid sex | Details → |
| 336 | Provider number, NPI and/or name used were incorrect. Note correction(s) and use on f… | Details → |
| 336 | Mental Health dx required Partial hospitalization service for non-mental health diagn… | Details → |
| 337 | This is a repayment. You submitted a refund for services which we are unable to ident… | Details → |
| 337 | Only therapy services provided Only activity therapy and/or occupational therapy serv… | Details → |
| 338 | This is a repayment. You submitted a refund in excess of what was required. | Details → |
| 338 | Invalid units for bilateral procedure Terminated bilateral procedure or terminated pr… | Details → |
| 339 | Bill returned to provider with application required to establish provider number. | Details → |
| 339 | Implanted dev code & administered sub do not match Inconsistency between the implante… | Details → |
| 340 | Denied. Submit bill on original L&I approved form. Photocopies cannot be processed. | Details → |
| 340 | Inpt procedures not payable Inpatient separate procedures not paid. | Details → |
| 341 | Side of body code is required for this diagnosis. | Details → |
| 341 | Multiple codes for same service Multiple codes for same service. | Details → |
| 342 | This diagnosis is not acceptable. L&I requires use of a more specific ICD. | Details → |
| 342 | Invalid dx for clinical trial Clinical trial requires diagnosis codes V707 as other t… | Details → |
| 343 | Denied. Interpreters must have prior authorization and bill L&I directly. | Details → |
| 343 | Modifier CA billed for multiple procedures Use of modifier CA with more than one proc… | Details → |
| 344 | Denied. The ICD diagnosis code is missing, invalid for first date of service or an E-… | Details → |
| 344 | Invalid service for OT code This OT code only billed on partial hospitalization claim… | Details → |
| 345 | Denied. Special exam and/or L&I investigation relating this condition to the injury i… | Details → |
| 345 | Invalid service for AT code AT service not payable outside the partial hospitalizatio… | Details → |
| 346 | Full DRG payment for inpatient stay made on this ICN. | Details → |
| 346 | Service not FDA approved Service provided prior to FDA approval. | Details → |
| 347 | Denied. Rebill therapy on outpatient bill. Submit other charges as adjustment to inpa… | Details → |
| 347 | Service not approved by NCD Service provided prior to date of National Coverage Deter… | Details → |
| 348 | Please note the provider number and use it on current bill forms you submit for hospi… | Details → |
| 348 | Service provided outside approval period Service provided outside approval period. | Details → |
| 349 | Denied. This service is not payable in addition to code 90670, 90676 or 90677. | Details → |
| 349 | Invalid pt status for CA modifier CA modifier requires patient status code 20. | Details → |
| 350 | Report is required when this procedure and/or modifier code is billed. No report was … | Details → |
| 350 | Billed amt cannot exceed $1.01) Charge exceeds token charge ($1.01). | Details → |
| 351 | Denied. Incorrect revenue code used for the described service billed. | Details → |
| 351 | Invalid condition code for bill type Partial hospitalization condition code 41 not ap… | Details → |
| 352 | This ICN paid at $0.00. Full DRG payment for this inpatient stay made on separate ICN… | Details → |
| 352 | Claim does not meet obs criteria Observation does not meet minimum hours, qualifying … | Details → |
| 353 | Denied. Code must be authorized before payment can be made. Call 800-848-0811 for aut… | Details → |
| 353 | Invalid bill type for observation Observation G codes only allowed with bill type 13x… | Details → |
| 354 | Denied. Bill/documentation detail is incomplete, invalid or missing. | Details → |
| 354 | Non-reportable for site of service Non-reportable for site of service. | Details → |
| 355 | The tooth number on your billing is invalid. It must be in the range 01 through 32. | Details → |
| 355 | E/M conditions not met for observation criteria E/M conditions not met and line item … | Details → |
| 356 | The tooth number is required for this procedure and was not on your submitted billing… | Details → |
| 357 | Payment processed. Future medical travel requires prior approval. Contact your Claim … | Details → |
| 357 | Incorrect billing of modifier FB or FC. Incorrect billing of modifier FB or FC. | Details → |
| 358 | Services provided are not greater than those usually required for the listed procedur… | Details → |
| 358 | Invalid code for place of service Mental health code not approved for partial hospita… | Details → |
| 359 | These services are generally provided as an adjunct to common medical services. | Details → |
| 359 | Invalid code for place of service Mental health service not payable outside the parti… | Details → |
| 360 | Circumstances do not clearly warrant additional charge beyond usual charge for basic … | Details → |
| 360 | Service provided outside approval period Service provided on or after effective date … | Details → |
| 361 | Calls and/or conferences with injured worker's attorney are not necessary medical ser… | Details → |
| 361 | Not a covered Medicaid benefit The patient does not have benefits for this service un… | Details → |
| 362 | Denied. The distance traveled does not justify payment of this meal. | Details → |
| 363 | Payment of service(s) made at L&I maximum allowable rate(s). | Details → |
| 364 | Payment made for the actual cost of service indicated on the receipt(s) attached to y… | Details → |
| 365 | Denied. This place of service is not authorized for this procedure. | Details → |
| 365 | Medical documentation required Please resubmit claim with the appropriate medical doc… | Details → |
| 366 | Denied. The provider specialty on the L&I record does not include this service. | Details → |
Medical claim denial codes — formally known as Claim Adjustment Reason Codes (CARC) — are standardized identifiers maintained by the X12 standards body and used across all Medicare, Medicaid, and commercial payer 835 electronic remittance transactions. When a claim is paid at a different amount than billed, at least one CARC code must accompany the remittance advice to indicate the specific reason for the adjustment.
The most frequently encountered codes include CO-16 (missing or invalid claim information), CO-45 (charges exceeding fee schedule), PR-1 (patient deductible), CO-29 (timely filing deadline exceeded), and CO-4 (procedure code inconsistent with modifier). Each represents a distinct, actionable reason that has a defined resolution pathway.