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 |
|---|---|---|
| 671 | Return letter for hospital bills whose charges need separation for unrelated conditio… | Details → |
| 672 | Letter for returning bills for unitemized CPT codes. | Details → |
| 673 | Return letter for prescription reimbursement to claimant for drug which requires auth… | Details → |
| 674 | Return letter for claimant reimbursement with charges for services over 12 months old… | Details → |
| 675 | Return letter for pharmacy bill with charges for services over 12 months old. | Details → |
| 680 | Return letter for bill submitted for an injured worker who was employed by Mayr Broth… | Details → |
| 698 | Return letter for bill which includes charges for services rendered during period cla… | Details → |
| 699 | Return letter for bill which includes charges for services rendered over 12 months ag… | Details → |
| 700 | Interest is the result of an audit.CR 225 N10, N199 | Details → |
| 701 | Denied. The amount of hours missed from work are not clear. | Details → |
| 702 | Procedure billed not allowed in combination with other code billed for this dos. Refe… | Details → |
| 703 | Adjusted. Only 1 unit of service allowed per day. Refer to current fee schedule. | Details → |
| 704 | Denied. Only 1 unit of service allowed per day. Refer to current fee schedule. | Details → |
| 740 | Denied. Supplies should be billed using the appropriate revenue code(s). | Details → |
| 742 | Transferred credit balance from provider number to payee number. | Details → |
| 743 | Transferred credit balance to payee number from provider number. | Details → |
| 744 | History only. Paid under correct claim number for this date/nature of injury. | Details → |
| 745 | Paid under correct provider number for date(s) of service. | Details → |
| 746 | Injured worker's accident rejected by L&I State Fund and service not authorized. Cont… | Details → |
| 747 | Balance of job mod costs must be billed to and paid by injured worker's employer. | Details → |
| 748 | Bill paid, but might be adjusted after receipt of utilization review (UR) post discha… | Details → |
| 800 | Only the technical portion of the x-ray is payable during the follow-up by the surgeo… | Details → |
| 801 | Denied. 908__ not allowed with E/M visit procedure codes. You must use psychotherapy … | Details → |
| 802 | Denied. Procedure code 76140 not payable in conjunction with these services. | Details → |
| 803 | Denied. These services are not payable in conjunction with modalities and/or treatmen… | Details → |
| 804 | Denied. Time and/or co-signature missing from bill. | Details → |
| 805 | Denied. Please refer to the HCPCS section of our current fee schedule for correct pro… | Details → |
| 806 | Denied. This service is not payable in addition to single examiner exams. | Details → |
| 807 | Denied. The provider specialty on the L&I record does not include radiology consultat… | Details → |
| 808 | Denied. Revenue code for Medicaid only. | Details → |
| 809 | Paid at fee schedule maximum. Modifier 22 requires unusual circumstances and supporti… | Details → |
| 810 | This patient is a participant in the managed care pilot program. | Details → |
| 811 | Portable/mobile x-rays not payable to hospital based providers. | Details → |
| 812 | Bill physician assistant with PA name, supervising physician name and physician provi… | Details → |
| 813 | Denied. Rental fees cannot exceed purchase price. | Details → |
| 814 | Denied. Lab work is not payable when billed with complex assessment. | Details → |
| 815 | Denied. Provider is not a L&I approved Independent Medical Examiner. | Details → |
| 816 | Denied. Please bill Kaiser / Attn: Kathleen Sharp / 2701 NW Vaughn #700 / Portland, O… | Details → |
| 817 | Free Standing surgical center not payable for this surgical procedure. | Details → |
| 818 | Denied. Bill the primary occupational medicine managed care provider. | Details → |
| 819 | Denied. Worker's MCPP participation period has ended. Rebill using fee for svc provid… | Details → |
| 820 | Denied. Service included in Pain Clinic fees and not payable separately. | Details → |
| 821 | Denied. Contact the primary occup. medicine managed care provider at 1-800-443-0996, … | Details → |
| 822 | Mangd care pilot claim. Only rpt of accdnt, initial ov and dx studies are payable by … | Details → |
| 823 | Denied. Pharmacological evaluation is not payable with an E/M procedure code. | Details → |
| 824 | Denied. Managed Care claim, please refer to PB 95-02. Per WAC 296-20-010 do not bill … | Details → |
| 825 | Revenue code 452 not allowed. Use 450 to bill 451/452 combined charges. | Details → |
| 826 | Procedure not authorized. Call 1st Health/EBP for review: 1-800-541-2894. Rebill when… | Details → |
| 827 | Denied. A supplemental medical report (code 1056M) was not requested and/or received. | Details → |
| 828 | Denied. Maximum of 11 sympathetic blocks have been billed and paid for this claim. | Details → |
| 829 | Denied. Two procedures w/the same descriptions have been billed, the higher value was… | Details → |
| 830 | Paid per Board of Industrial Insurance Appeals (BIIA) order or agreement of parties. | Details → |
| 831 | Denied. Service is payable under a different procedure code. Refer to fee schedule & … | Details → |
| 832 | Denied. These services are not payable during hearing aid warranty period. | Details → |
| 833 | Denied. Bill returned with provider application. Provider address on file does not ma… | Details → |
| 834 | Please note the provider number. You must use this number when billing for work harde… | Details → |
| 835 | Denied. Additional views, slices or levels of CT scans are not payable. | Details → |
| 836 | Denied. Outpatient dates of service cannot overlap inpatient stay. | Details → |
| 837 | Denied. The date of service does not correspond to the supporting documents date of s… | Details → |
| 838 | Procedure not authorized. Call UR vendor 800-541-2894. Once authorized, Rebill for to… | 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.