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 |
|---|---|---|
| N451 | Missing Admission Summary Report. | Details → |
| N452 | Incomplete/invalid Admission Summary Report. | Details → |
| N452 | Incomplete/invalid Admission Summary Report. | Details → |
| N453 | Missing Consultation Report. | Details → |
| N453 | Missing Consultation Report. | Details → |
| N454 | Incomplete/invalid Consultation Report. | Details → |
| N454 | Incomplete/invalid Consultation Report. | Details → |
| N455 | Missing Physician Order. | Details → |
| N455 | Missing Physician Order. | Details → |
| N456 | Incomplete/invalid Physician Order. | Details → |
| N456 | Incomplete/invalid Physician Order. | Details → |
| N457 | Missing Diagnostic Report. | Details → |
| N457 | Missing Diagnostic Report. | Details → |
| N458 | Incomplete/invalid Diagnostic Report. | Details → |
| N458 | Incomplete/invalid Diagnostic Report. | Details → |
| N459 | Missing Discharge Summary. | Details → |
| N459 | Missing Discharge Summary. | Details → |
| N46 | Missing/incomplete/invalid admission hour. | Details → |
| N46 | Missing/incomplete/invalid admission hour. | Details → |
| N460 | Incomplete/invalid Discharge Summary. | Details → |
| N460 | Incomplete/invalid Discharge Summary. | Details → |
| N461 | Missing Nursing Notes. | Details → |
| N461 | Missing Nursing Notes. | Details → |
| N462 | Incomplete/invalid Nursing Notes. | Details → |
| N462 | Incomplete/invalid Nursing Notes. | Details → |
| N463 | Missing support data for claim. | Details → |
| N463 | Missing support data for claim. | Details → |
| N464 | Incomplete/invalid support data for claim. | Details → |
| N464 | Incomplete/invalid support data for claim. | Details → |
| N465 | Missing Physical Therapy Notes/Report. | Details → |
| N465 | Missing Physical Therapy Notes/Report. | Details → |
| N466 | Incomplete/invalid Physical Therapy Notes/Report. | Details → |
| N466 | Incomplete/invalid Physical Therapy Notes/Report. | Details → |
| N467 | Missing Tests and Analysis Report. | Details → |
| N467 | Missing Tests and Analysis Report. | Details → |
| N468 | Incomplete/invalid Report of Tests and Analysis Report. | Details → |
| N468 | Incomplete/invalid Report of Tests and Analysis Report. | Details → |
| N469 | Alert: Claim/Service(s) subject to appeal process, see section 935 of Medicare Prescr… | Details → |
| N469 | Alert: Claim/Service(s) subject to appeal process, see section 935 of Medicare Prescr… | Details → |
| N47 | Claim conflicts with another inpatient stay. | Details → |
| N47 | Claim conflicts with another inpatient stay. | Details → |
| N470 | This payment will complete the mandatory medical reimbursement limit. | Details → |
| N470 | This payment will complete the mandatory medical reimbursement limit. | Details → |
| N471 | Missing/incomplete/invalid HIPPS Rate Code. | Details → |
| N471 | Missing/incomplete/invalid HIPPS Rate Code. | Details → |
| N472 | Payment for this service has been issued to another provider. | Details → |
| N472 | Payment for this service has been issued to another provider. | Details → |
| N473 | Missing certification. | Details → |
| N473 | Missing certification. | Details → |
| N474 | Incomplete/invalid certification. | Details → |
| N474 | Incomplete/invalid certification. | Details → |
| N475 | Missing completed referral form. | Details → |
| N475 | Missing completed referral form. | Details → |
| N476 | Incomplete/invalid completed referral form. | Details → |
| N476 | Incomplete/invalid completed referral form. | Details → |
| N477 | Missing Dental Models. | Details → |
| N477 | Missing Dental Models. | Details → |
| N478 | Incomplete/invalid Dental Models. | Details → |
| N478 | Incomplete/invalid Dental Models. | Details → |
| N479 | Missing Explanation of Benefits (Coordination of Benefits or Medicare Secondary Payer… | 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.