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 |
|---|---|---|
| N479 | Missing Explanation of Benefits (Coordination of Benefits or Medicare Secondary Payer… | Details → |
| N48 | Claim information does not agree with information received from other insurance carri… | Details → |
| N48 | Claim information does not agree with information received from other insurance carri… | Details → |
| N480 | Incomplete/invalid Explanation of Benefits (Coordination of Benefits or Medicare Seco… | Details → |
| N480 | Incomplete/invalid Explanation of Benefits (Coordination of Benefits or Medicare Seco… | Details → |
| N481 | Missing Models. | Details → |
| N481 | Missing Models. | Details → |
| N482 | Incomplete/invalid Models. | Details → |
| N482 | Incomplete/invalid Models. | Details → |
| N483 | Missing Periodontal Charts. | Details → |
| N483 | Missing Periodontal Charts. | Details → |
| N484 | Incomplete/invalid Periodontal Charts. | Details → |
| N484 | Incomplete/invalid Periodontal Charts. | Details → |
| N485 | Missing Physical Therapy Certification. | Details → |
| N485 | Missing Physical Therapy Certification. | Details → |
| N486 | Incomplete/invalid Physical Therapy Certification. | Details → |
| N486 | Incomplete/invalid Physical Therapy Certification. | Details → |
| N487 | Missing Prosthetics or Orthotics Certification. | Details → |
| N487 | Missing Prosthetics or Orthotics Certification. | Details → |
| N488 | Incomplete/invalid Prosthetics or Orthotics Certification. | Details → |
| N488 | Incomplete/invalid Prosthetics or Orthotics Certification. | Details → |
| N489 | Missing referral form. | Details → |
| N489 | Missing referral form. | Details → |
| N49 | Court ordered coverage information needs validation. | Details → |
| N49 | Court ordered coverage information needs validation. | Details → |
| N490 | Incomplete/invalid referral form. | Details → |
| N490 | Incomplete/invalid referral form. | Details → |
| N491 | Missing/Incomplete/Invalid Exclusionary Rider Condition. | Details → |
| N491 | Missing/Incomplete/Invalid Exclusionary Rider Condition. | Details → |
| N492 | Alert: A network provider may bill the member for this service if the member requeste… | Details → |
| N492 | Alert: A network provider may bill the member for this service if the member requeste… | Details → |
| N493 | Missing Doctor First Report of Injury. | Details → |
| N493 | Missing Doctor First Report of Injury. | Details → |
| N494 | Incomplete/invalid Doctor First Report of Injury. | Details → |
| N494 | Incomplete/invalid Doctor First Report of Injury. | Details → |
| N495 | Missing Supplemental Medical Report. | Details → |
| N495 | Missing Supplemental Medical Report. | Details → |
| N496 | Incomplete/invalid Supplemental Medical Report. | Details → |
| N496 | Incomplete/invalid Supplemental Medical Report. | Details → |
| N497 | Missing Medical Permanent Impairment or Disability Report. | Details → |
| N497 | Missing Medical Permanent Impairment or Disability Report. | Details → |
| N498 | Incomplete/invalid Medical Permanent Impairment or Disability Report. | Details → |
| N498 | Incomplete/invalid Medical Permanent Impairment or Disability Report. | Details → |
| N499 | Missing Medical Legal Report. | Details → |
| N499 | Missing Medical Legal Report. | Details → |
| N5 | EOB received from previous payer. Claim not on file. | Details → |
| N5 | EOB received from previous payer. Claim not on file. | Details → |
| N50 | Missing/incomplete/invalid discharge information. | Details → |
| N50 | Missing/incomplete/invalid discharge information. | Details → |
| N500 | Incomplete/invalid Medical Legal Report. | Details → |
| N500 | Incomplete/invalid Medical Legal Report. | Details → |
| N501 | Missing Vocational Report. | Details → |
| N501 | Missing Vocational Report. | Details → |
| N502 | Incomplete/invalid Vocational Report. | Details → |
| N502 | Incomplete/invalid Vocational Report. | Details → |
| N503 | Missing Work Status Report. | Details → |
| N503 | Missing Work Status Report. | Details → |
| N504 | Incomplete/invalid Work Status Report. | Details → |
| N504 | Incomplete/invalid Work Status Report. | Details → |
| N505 | Alert: This response includes only services that could be estimated in real-time. No … | 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.