CO-204: Service Not Authorized on Date of Service
CO (Contractual Obligation)What is CO-204?
CO-204 is a Contractual Obligation code indicating the specific service was not authorized for the date of service. Similar to CO-197, but CO-204 specifically addresses date-of-service discrepancies between the auth and the claim.
Why Does CO-204 Occur?
- Service performed on a date not covered by the authorization window.
- Authorization covers a different date range than the date of service on the claim.
- Authorization was obtained but the service was delayed beyond the auth's valid period.
How to Fix CO-204 Denials
- Check the authorization's valid date range against the date of service on the claim.
- If the dates are within the auth window and the payer's records are wrong, appeal with the auth documentation showing the valid date range.
- If the auth expired, request a new authorization or an extension from the payer.
- Resubmit with the corrected date or updated auth number.
CO-204 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-204, check these related codes: CO-197 (precertification absent), CO-23 (prior auth not obtained), CO-21 (authorization absent).
Common Questions About CO-204
What does CO-204 mean?
CO-204 indicates service not authorized on date of service. Check the RARC code on the EOB for the specific reason and follow the resolution steps above.
Can I appeal a CO-204 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-204 denials before submission with authorization date matching. See how pre-submit claim scoring works.