Denial code CO-183: Referring provider not eligible to refer
The provider listed as referring is not enrolled, not eligible, or not correctly identified for referrals with this payer.
The referring provider is not eligible to refer the service billed.
What CO-183 actually means
The payer validated the referring NPI on the claim against its provider file and rejected it. The referral itself may be entirely legitimate — the problem is that the referring provider is not enrolled with this payer, is not eligible to make referrals, or was identified with the wrong NPI. Because the referring provider is outside your organisation, this denial requires reaching out rather than correcting internally.
Why this denial happens
- The referring provider is not enrolled or is not participating with the payer.
- The wrong NPI was submitted for the referring provider (group NPI instead of individual, for instance).
- The referring provider’s enrolment is inactive or lapsed.
- The provider type is not eligible to refer for that service.
How to resolve a CO-183 denial
- Verify the referring provider’s individual NPI and enrolment status with the payer.
- Correct the NPI and resubmit where the wrong identifier was sent.
- Obtain a referral from an eligible provider where the original referrer is ineligible.
How to prevent it
- Validate referring provider NPIs against the payer’s provider file at order entry.
- Store individual NPIs for frequent referral sources rather than re-keying them per claim.
Frequently asked
What does denial code CO-183 mean?
The provider listed as referring is not enrolled, not eligible, or not correctly identified for referrals with this payer. The X12 description reads: "The referring provider is not eligible to refer the service billed."
How do I fix a CO-183 denial?
Verify the referring provider’s individual NPI and enrolment status with the payer. Correct the NPI and resubmit where the wrong identifier was sent. Obtain a referral from an eligible provider where the original referrer is ineligible.
Can CO-183 be billed to the patient?
Generally no. The recommended path for this code is "appeal or correct and resubmit" — check your payer agreement before transferring any balance to the patient.
Related denial codes
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General revenue-cycle guidance, not legal, coding, or payer-specific advice. Claim adjustment reason codes are maintained by X12 and are revised periodically; payer policy and your provider agreement govern in any specific case. Always read the remark codes transmitted with the denial — they frequently carry the detail this code does not.