CO-279Contractual ObligationContractual
CO-279 Denial Code: Not a preferred/narrow-network provider
You're contracted but outside the member's narrow/preferred network tier — services denied or paid at the non-preferred level.
Why CO-279 happens
- ●Member's product uses a narrow network your contract tier isn't part of
- ●Tiered network products paying differently by tier
How to fix a CO-279 denial
- 1
Verify the member's specific product/network; appeal only if your tier status is wrong
- 2
For emergencies, invoke network-adequacy/emergency protections
How to prevent it
Eligibility checks must capture the product/network tier, not just the payer name.
Drowning in CO-279 denials?
OakClaim works every denial within 48 hours and builds prevention rules so they stop recurring.