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 |
|---|---|---|
| N162 | Alert: Although your claim was paid, you have billed for a test/specialty not include… | Details → |
| N163 | Medical record does not support code billed per the code definition. | Details → |
| N163 | Medical record does not support code billed per the code definition. | Details → |
| N164 | Transportation to/from this destination is not covered. | Details → |
| N164 | Transportation to/from this destination is not covered. | Details → |
| N165 | Transportation in a vehicle other than an ambulance is not covered. | Details → |
| N165 | Transportation in a vehicle other than an ambulance is not covered. | Details → |
| N166 | Payment denied/reduced because mileage is not covered when the patient is not in the … | Details → |
| N166 | Payment denied/reduced because mileage is not covered when the patient is not in the … | Details → |
| N167 | Charges exceed the post-transplant coverage limit. | Details → |
| N167 | Charges exceed the post-transplant coverage limit. | Details → |
| N168 | The patient must choose an option before a payment can be made for this procedure/ eq… | Details → |
| N168 | The patient must choose an option before a payment can be made for this procedure/ eq… | Details → |
| N169 | This drug/service/supply is covered only when the associated service is covered. | Details → |
| N169 | This drug/service/supply is covered only when the associated service is covered. | Details → |
| N17 | Per admission deductible. | Details → |
| N17 | Per admission deductible. | Details → |
| N170 | A new/revised/renewed certificate of medical necessity is needed. | Details → |
| N170 | A new/revised/renewed certificate of medical necessity is needed. | Details → |
| N171 | Payment for repair or replacement is not covered or has exceeded the purchase price. | Details → |
| N171 | Payment for repair or replacement is not covered or has exceeded the purchase price. | Details → |
| N172 | The patient is not liable for the denied/adjusted charge(s) for receiving any updated… | Details → |
| N172 | The patient is not liable for the denied/adjusted charge(s) for receiving any updated… | Details → |
| N173 | No qualifying hospital stay dates were provided for this episode of care. | Details → |
| N173 | No qualifying hospital stay dates were provided for this episode of care. | Details → |
| N174 | This is not a covered service/procedure/ equipment/bed, however patient liability is … | Details → |
| N174 | This is not a covered service/procedure/ equipment/bed, however patient liability is … | Details → |
| N175 | Missing review organization approval. | Details → |
| N175 | Missing review organization approval. | Details → |
| N176 | Services provided aboard a ship are covered only when the ship is of United States re… | Details → |
| N176 | Services provided aboard a ship are covered only when the ship is of United States re… | Details → |
| N177 | Alert: We did not send this claim to patient's other insurer. They have indicated no … | Details → |
| N177 | Alert: We did not send this claim to patient's other insurer. They have indicated no … | Details → |
| N178 | Missing pre-operative images/visual field results. | Details → |
| N178 | Missing pre-operative images/visual field results. | Details → |
| N179 | Additional information has been requested from the member. The charges will be recons… | Details → |
| N179 | Additional information has been requested from the member. The charges will be recons… | Details → |
| N18 | Payment based on the Medicare allowed amount. | Details → |
| N18 | Payment based on the Medicare allowed amount. | Details → |
| N180 | This item or service does not meet the criteria for the category under which it was b… | Details → |
| N180 | These are non-covered services because this is not deemed a 'medical necessity' by th… | Details → |
| N180 | Non-covered charge(s). Item does not meet the criteria for the category under which i… | Details → |
| N180 | This item or service does not meet the criteria for the category under which it was b… | Details → |
| N181 | Additional information is required from another provider involved in this service. | Details → |
| N181 | Additional information is required from another provider involved in this service. | Details → |
| N182 | This claim/service must be billed according to the schedule for this plan. | Details → |
| N182 | This claim/service must be billed according to the schedule for this plan. | Details → |
| N183 | Alert: This is a predetermination advisory message, when this service is submitted fo… | Details → |
| N183 | Alert: This is a predetermination advisory message, when this service is submitted fo… | Details → |
| N184 | Rebill technical and professional components separately. | Details → |
| N184 | Rebill technical and professional components separately. | Details → |
| N185 | Alert: Do not resubmit this claim/service. | Details → |
| N185 | Alert: Do not resubmit this claim/service. | Details → |
| N186 | Non-Availability Statement (NAS) required for this service. Contact the nearest Milit… | Details → |
| N186 | Non-Availability Statement (NAS) required for this service. Contact the nearest Milit… | Details → |
| N187 | Alert: You may request a review in writing within the required time limits following … | Details → |
| N187 | Alert: You may request a review in writing within the required time limits following … | Details → |
| N188 | The approved level of care does not match the procedure code submitted. | Details → |
| N188 | The approved level of care does not match the procedure code submitted. | Details → |
| N189 | Alert: This service has been paid as a one-time exception to the plan's benefit restr… | 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.