CO-183Contractual ObligationProvider Enrollment
CO-183 Denial Code: Referring provider not eligible to refer
The referring provider on the claim can't legally/contractually refer this service — often a PECOS enrollment or provider-type issue.
Why CO-183 happens
- ●Referring physician not enrolled in Medicare PECOS
- ●Provider type not authorized to refer this service (e.g., excluded provider)
How to fix a CO-183 denial
- 1
Verify the referrer's enrollment; obtain a new referral from an eligible provider if needed
- 2
Correct NPI errors that misidentified the referrer and rebill
How to prevent it
Validate referring-provider PECOS enrollment at order entry for Medicare patients.
Drowning in CO-183 denials?
OakClaim works every denial within 48 hours and builds prevention rules so they stop recurring.