CO-279: Services Not Provided by Preferred Network Providers
You are not in this patient's preferred network tier. Verify your tier status, check for single case agreements, and contact provider relations if you believe the classification is wrong.
What Does CO-279 Mean?
CO-279 means the provider is not in the patient's preferred network tier and the payment difference is a contractual matter between the provider and payer. The provider cannot post as a contractual adjustment for the difference. This commonly occurs with tiered network plans where providers in lower tiers receive reduced reimbursement.
CARC 279 indicates that the services billed were rendered by a provider who is not part of the patient's preferred or narrow network tier. This is distinct from a simple out-of-network denial — it specifically targets plans with multiple network tiers where the provider may be contracted with the payer but is not in the patient's specific preferred tier.
The financial impact depends on the Group Code. Under CO, the provider absorbs the cost difference because they are not in the preferred tier — this is common with tiered network plans where contracted providers receive different reimbursement levels. Under PR, the patient is responsible because they chose to receive services from a non-preferred provider, and the cost difference or full charge is their obligation.
This code has become more common as payers expand tiered network designs and narrow network products. A provider who was previously in a broad network may find themselves outside a patient's narrow or preferred tier, triggering this denial even though they still have a contract with the payer.
Common Causes
| Cause | Frequency |
|---|---|
| Services rendered by out-of-network provider The healthcare provider delivering the services is not part of the patient's insurance plan's preferred network, resulting in denial or reduced payment | Most Common |
| Network tier limitation The provider is in the broader network but not in the patient's specific preferred or narrow network tier | Common |
| Missing referral for specialist services The patient did not obtain a required referral from their primary care physician before seeing a specialist in a non-preferred network | Common |
| Lack of prior authorization for out-of-network services Required pre-approval for out-of-network services was not obtained before the service was rendered | Common |
| Provider network status changed The provider's network participation status changed between the time of scheduling and the time of service delivery | Occasional |
How to Resolve
- Verify network tier status Confirm your current tier assignment with the patient's specific plan — you may be contracted but not in the preferred tier.
- Check for agreements Review whether a single case agreement or prior authorization exists that covers services at the preferred rate.
- Contact provider relations If you believe you should be classified as preferred, contact the payer with updated credentialing information.
- Appeal for extenuating circumstances For emergency care or situations where no preferred provider was available, file an appeal with documentation.
File an appeal with documentation showing the medical necessity for out-of-network care, evidence that no in-network provider was available for the service, any referral or authorization documentation, and a letter explaining the circumstances requiring non-preferred network services.
Common RARC Pairings
The RARC code tells you exactly what triggered the CO-279:
| RARC | Description |
|---|---|
| N381 | Alert: Consult your contractual agreement for restrictions, billing, and payment information. Review the network provisions in the patient's plan to understand preferred provider requirements → |
| N130 | Alert: You may need to review plan documents or guidelines to determine service restrictions. Check the plan's network tier requirements and out-of-network coverage limitations → |
How to Prevent CO-279
- Verify your network tier status with each patient's plan before providing services
- Monitor network participation agreements and tier assignments across payers
- Implement eligibility verification that identifies network tier restrictions at check-in
- Obtain prior authorization or single case agreements when services may fall outside the preferred tier
General Prevention
- Verify network participation status before service delivery using electronic eligibility tools
- Train staff on network-specific limitations and preferred provider requirements
- Communicate network restrictions to patients at scheduling and check-in
- Obtain prior authorization for out-of-network services when applicable
- Regularly review and update provider network contracts
Also Filed As
The same CARC 279 may appear with different Group Codes:
Related Denial Codes
Sources
- https://www.mdclarity.com/denial-code/279
- https://resdac.org/sites/datadocumentation.resdac.org/files/Adjustment%20Reason%20Code%20Code%20Table%20(TAF%20Claims).txt
- https://x12.org/codes/claim-adjustment-reason-codes
- Codes maintained by X12. Visit x12.org for official definitions.