CO-23: Prior Authorization Not Obtained
CO (Contractual Obligation)What is CO-23?
CO-23 is a Contractual Obligation code indicating the impact of prior authorization was not obtained before the service. Like CO-197 and CO-21, this code means the payer required pre-approval that was not on file. Payers use CO-23, CO-21, and CO-197 interchangeably depending on their system.
Why Does CO-23 Occur?
- Prior authorization not obtained for a service that requires it.
- Auth obtained but for a different procedure code, date range, or provider.
- Auth request was submitted but not yet approved when the service was rendered.
- Emergency service not exempt from auth requirements under the patient's plan.
How to Fix CO-23 Denials
- Check the payer's auth requirements for the specific CPT code.
- If auth was obtained, verify the auth number, procedure code, date range, and provider match the claim.
- Request retroactive authorization if the payer allows it (typically for emergencies within 24-72 hours).
- Appeal with documentation of medical necessity if retro auth is not available.
CO-23 by Payer
| Payer | Common RARC | Appeal Deadline | Notes |
|---|---|---|---|
| UnitedHealthcare | Varies | 60 days from remittance | Reconsideration required before formal appeal. |
| Anthem | Varies | 365 days from denial notice | Check state-specific provider manual for variations. |
| Aetna | Varies | 180 days from denial | Strict in-network filing enforcement. |
| Cigna | Varies | 180 days from denial | Cigna COB team: 1-800-244-6224. |
| Medicare | Varies | 120 days (redetermination at MAC) | Five levels of appeal starting with MAC redetermination. |
Related CARC Codes
If you are seeing CO-23, check these related codes: CO-197 (precertification absent), CO-23 (prior auth not obtained), CO-21 (authorization absent).
Common Questions About CO-23
What does CO-23 mean?
CO-23 indicates prior authorization not obtained. Check the RARC code on the EOB for the specific reason and follow the resolution steps above.
Can I appeal a CO-23 denial?
Yes. Commercial payers allow 60-365 days to appeal depending on the payer. Gather supporting documentation before filing. Medicare allows 120 days for a redetermination request.
Altair catches CO-23 denials before submission with prior auth requirement lookup. See how pre-submit claim scoring works.