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 |
|---|---|---|
| N826 | Patient did not meet the inclusion criteria for the Medicare Shared Savings Program. | Details → |
| N827 | Missing/Incomplete/Invalid Federal Information Processing Standard (FIPS) Code. | Details → |
| N827 | Missing/Incomplete/Invalid Federal Information Processing Standard (FIPS) Code. | Details → |
| N828 | Alert: Payment is suppressed due to a contracted funding. | Details → |
| N828 | Alert: Payment is suppressed due to a contracted funding. | Details → |
| N829 | Missing/incomplete/invalid Diagnostics Exchange Z-Code Identifier. | Details → |
| N829 | Missing/incomplete/invalid Diagnostics Exchange Z-Code Identifier. | Details → |
| N83 | No appeal rights. Adjudicative decision based on the provisions of a demonstration pr… | Details → |
| N83 | No appeal rights. Adjudicative decision based on the provisions of a demonstration pr… | Details → |
| N830 | Alert: The charge[s] for this service was processed in accordance with Federal/ State… | Details → |
| N830 | Alert: The charge[s] for this service was processed in accordance with Federal/ State… | Details → |
| N831 | You have not responded to requests to revalidate your provider/supplier enrollment in… | Details → |
| N831 | You have not responded to requests to revalidate your provider/supplier enrollment in… | Details → |
| N832 | Duplicate occurrence code/occurrence span code. | Details → |
| N832 | Duplicate occurrence code/occurrence span code. | Details → |
| N833 | Patient share of cost waived. | Details → |
| N833 | Patient share of cost waived. | Details → |
| N834 | Jurisdiction exempt from sales and health tax charges. | Details → |
| N834 | Jurisdiction exempt from sales and health tax charges. | Details → |
| N835 | Unrelated Service/procedure/treatment is reduced. The balance of this charge is the p… | Details → |
| N835 | Unrelated Service/procedure/treatment is reduced. The balance of this charge is the p… | Details → |
| N836 | Provider W9 or Payee Registration not on file. | Details → |
| N836 | Provider W9 or Payee Registration not on file. | Details → |
| N837 | Alert: Missing modifier was added. | Details → |
| N837 | Alert: Missing modifier was added. | Details → |
| N838 | Alert: Service/procedure postponed due to a federal, state, or local mandate/disaster… | Details → |
| N838 | Alert: Service/procedure postponed due to a federal, state, or local mandate/disaster… | Details → |
| N839 | The procedure code was added/changed because the level of service exceeds the compens… | Details → |
| N839 | The procedure code was added/changed because the level of service exceeds the compens… | Details → |
| N84 | Alert: Further installment payments are forthcoming. | Details → |
| N84 | Alert: Further installment payments are forthcoming. | Details → |
| N840 | Worker's compensation claim filed with a different state. | Details → |
| N840 | Worker's compensation claim filed with a different state. | Details → |
| N841 | Alert: North Dakota Administrative Rule 92-01-02-50.3. | Details → |
| N841 | Alert: North Dakota Administrative Rule 92-01-02-50.3. | Details → |
| N842 | Alert: Patient cannot be billed for charges. | Details → |
| N842 | Alert: Patient cannot be billed for charges. | Details → |
| N843 | Missing/incomplete/invalid Core-Based Statistical Area (CBSA) code. | Details → |
| N843 | Missing/incomplete/invalid Core-Based Statistical Area (CBSA) code. | Details → |
| N844 | This claim, or a portion of this claim, was processed in accordance with the Nebraska… | Details → |
| N844 | This claim, or a portion of this claim, was processed in accordance with the Nebraska… | Details → |
| N845 | Alert: Nebraska Legislative LB997 July 24, 2020 - Out of Network Emergency Medical Ca… | Details → |
| N845 | Alert: Nebraska Legislative LB997 July 24, 2020 - Out of Network Emergency Medical Ca… | Details → |
| N846 | National Drug Code (NDC) supplied does not correspond to the HCPCs/CPT billed. | Details → |
| N846 | National Drug Code (NDC) supplied does not correspond to the HCPCs/CPT billed. | Details → |
| N847 | National Drug Code (NDC) billed is obsolete. | Details → |
| N847 | National Drug Code (NDC) billed is obsolete. | Details → |
| N848 | National Drug Code (NDC) billed cannot be associated with a product. | Details → |
| N848 | National Drug Code (NDC) billed cannot be associated with a product. | Details → |
| N849 | Missing Tooth Clause: Tooth missing prior to the member effective date. | Details → |
| N849 | Missing Tooth Clause: Tooth missing prior to the member effective date. | Details → |
| N85 | Alert: This is the final installment payment. | Details → |
| N85 | Alert: This is the final installment payment. | Details → |
| N850 | Missing/incomplete/invalid narrative explaining/describing this service/treatment. | Details → |
| N850 | Missing/incomplete/invalid narrative explaining/describing this service/treatment. | Details → |
| N851 | Payment reduced because services were furnished by a therapy assistant. | Details → |
| N851 | Payment reduced because services were furnished by a therapy assistant. | Details → |
| N852 | The pay-to and rendering provider tax identification numbers (TINs) do not match | Details → |
| N852 | The pay-to and rendering provider tax identification numbers (TINs) do not match | Details → |
| N853 | The number of modalities performed per session exceeds our acceptable maximum. | 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.