CO-55: Claim/Encounter Received Out of Order
CO (Contractual Obligation)What is CO-55?
CO-55 is a Contractual Obligation code indicating the claim was received out of chronological order, and processing is suspended until prior claims are resolved. This typically happens with inpatient stays or sequential claims.
Why Does CO-55 Occur?
- Interim bill submitted before the final bill for the same encounter.
- Claims for a multi-day stay submitted out of date order.
- Replacement claim received before the original claim was processed.
How to Fix CO-55 Denials
- Wait for the prior claim to process before resubmitting.
- If the prior claim has been adjudicated, resubmit the current claim with the prior claim's reference number.
- For inpatient stays, submit claims in chronological order from admission to discharge.
CO-55 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-55, check these related codes: CO-16 (claim differs), CO-45 (fee schedule), CO-29 (timely filing).
Common Questions About CO-55
What does CO-55 mean?
CO-55 indicates claim/encounter received out of order. Check the RARC code on the EOB for the specific reason and follow the resolution steps above.
Can I appeal a CO-55 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-55 denials before submission with claim sequencing. See how pre-submit claim scoring works.