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 |
|---|---|---|
| N425 | Statutorily excluded service(s). | Details → |
| N425 | Non-covered charge(s). Medicare does not pay for this service/equipment/drug. | Details → |
| N425 | Statutorily excluded service(s). | Details → |
| N426 | No coverage when self-administered. | Details → |
| N426 | No coverage when self-administered. | Details → |
| N427 | Payment for eyeglasses or contact lenses can be made only after cataract surgery. | Details → |
| N427 | Payment for eyeglasses or contact lenses can be made only after cataract surgery. | Details → |
| N428 | Not covered when performed in this place of service. | Details → |
| N428 | Not covered when performed in this place of service. | Details → |
| N429 | Not covered when considered routine. | Details → |
| N429 | Not covered when considered routine. | Details → |
| N43 | Bed hold or leave days exceeded. | Details → |
| N43 | Bed hold or leave days exceeded. | Details → |
| N430 | Procedure code is inconsistent with the units billed. | Details → |
| N430 | Procedure code is inconsistent with the units billed. | Details → |
| N431 | Not covered with this procedure. | Details → |
| N431 | Not covered with this procedure. | Details → |
| N432 | Alert: Adjustment based on a Recovery Audit. | Details → |
| N432 | Alert: Adjustment based on a Recovery Audit. | Details → |
| N433 | Resubmit this claim using only your National Provider Identifier (NPI). | Details → |
| N433 | Resubmit this claim using only your National Provider Identifier (NPI). | Details → |
| N434 | Missing/Incomplete/Invalid Present on Admission indicator. | Details → |
| N434 | Missing/Incomplete/Invalid Present on Admission indicator. | Details → |
| N435 | Exceeds number/frequency approved /allowed within time period without support documen… | Details → |
| N435 | Exceeds number/frequency approved /allowed within time period without support documen… | Details → |
| N436 | The injury claim has not been accepted and a mandatory medical reimbursement has been… | Details → |
| N436 | The injury claim has not been accepted and a mandatory medical reimbursement has been… | Details → |
| N437 | Alert: If the injury claim is accepted, these charges will be reconsidered. | Details → |
| N437 | Alert: If the injury claim is accepted, these charges will be reconsidered. | Details → |
| N438 | This jurisdiction only accepts paper claims. | Details → |
| N438 | This jurisdiction only accepts paper claims. | Details → |
| N439 | Missing anesthesia physical status report/indicators. | Details → |
| N439 | Missing anesthesia physical status report/indicators. | Details → |
| N44 | Payer's share of regulatory surcharges, assessments, allowances or health care-relate… | Details → |
| N44 | Payer's share of regulatory surcharges, assessments, allowances or health care-relate… | Details → |
| N440 | Incomplete/invalid anesthesia physical status report/indicators. | Details → |
| N440 | Incomplete/invalid anesthesia physical status report/indicators. | Details → |
| N441 | This missed/cancelled appointment is not covered. | Details → |
| N441 | This missed/cancelled appointment is not covered. | Details → |
| N442 | Payment based on an alternate fee schedule. | Details → |
| N442 | Payment based on an alternate fee schedule. | Details → |
| N443 | Missing/incomplete/invalid total time or begin/end time. | Details → |
| N443 | Missing/incomplete/invalid total time or begin/end time. | Details → |
| N444 | Alert: This facility has not filed the Election for High Cost Outlier form with the D… | Details → |
| N444 | Alert: This facility has not filed the Election for High Cost Outlier form with the D… | Details → |
| N445 | Missing document for actual cost or paid amount. | Details → |
| N445 | Missing document for actual cost or paid amount. | Details → |
| N446 | Incomplete/invalid document for actual cost or paid amount. | Details → |
| N446 | Incomplete/invalid document for actual cost or paid amount. | Details → |
| N447 | Payment is based on a generic equivalent as required documentation was not provided. | Details → |
| N447 | Payment is based on a generic equivalent as required documentation was not provided. | Details → |
| N448 | This drug/service/supply is not included in the fee schedule or contracted/legislated… | Details → |
| N448 | This drug/service/supply is not included in the fee schedule or contracted/legislated… | Details → |
| N449 | Payment based on a comparable drug/service/supply. | Details → |
| N449 | Payment based on a comparable drug/service/supply. | Details → |
| N45 | Payment based on authorized amount. | Details → |
| N45 | Payment based on authorized amount. | Details → |
| N450 | Covered only when performed by the primary treating physician or the designee. | Details → |
| N450 | Covered only when performed by the primary treating physician or the designee. | Details → |
| N451 | Missing Admission Summary Report. | 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.