CO-31: Patient Cannot Be Identified as Plan Enrollee
CO (Contractual Obligation)What is CO-31?
CO-31 is a Contractual Obligation code indicating the payer cannot identify the patient as an enrolled member of the plan. The subscriber ID, name, or date of birth on the claim does not match the payer's records.
Why Does CO-31 Occur?
- Subscriber ID number is incorrect on the claim.
- Patient name or date of birth does not match the payer's enrollment file.
- Patient is enrolled under a different subscriber (e.g., spouse, parent) but the claim was not submitted under the correct subscriber ID.
- New patient enrollment has not processed in the payer's system yet.
How to Fix CO-31 Denials
- Verify the subscriber ID, patient name, and date of birth against the insurance card and the payer portal.
- If the information is correct but the payer cannot find the patient, call the payer's enrollment department to confirm coverage.
- Resubmit with corrected subscriber information.
- If the patient is newly enrolled, wait for the enrollment to process and resubmit.
CO-31 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-31, check these related codes: CO-44 (subscriber not eligible), CO-27 (coverage terminated), CO-26 (prior to coverage).
Common Questions About CO-31
What does CO-31 mean?
CO-31 indicates patient cannot be identified as plan enrollee. Check the RARC code on the EOB for the specific reason and follow the resolution steps above.
Can I appeal a CO-31 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-31 denials before submission with patient eligibility matching. See how pre-submit claim scoring works.