OA-31: Patient Not Identified as Insured

What Does OA-31 Mean?

OA-31 signals that the patient identification failure does not fall cleanly on the provider or patient. This pairing typically appears in coordination of benefits situations — for example, a secondary payer cannot match the patient because the COB linkage was never established, or a payer system experienced a data feed error that temporarily removed an active member from their enrollment file. The resolution approach depends on the specific circumstances.

When CARC 31 appears on a remittance, the payer searched its enrollment database using the identifiers on your claim and found no match. The patient could not be linked to any active policy. This does not necessarily mean the patient is uninsured — it means the information you submitted does not align with what the payer has on file.

The most frequent trigger is a data entry error at registration: a transposed digit in the member ID, a misspelled last name, a date of birth keyed incorrectly, or a subscriber ID confused with the group number. Less commonly, CARC 31 appears when the claim was routed to the wrong payer entirely — the patient changed jobs and insurance, but your system still shows the old carrier. It can also surface when the patient's enrollment has not yet been loaded into the payer's system, particularly with new-year plan changes or employer group transitions.

Under Group Code CO, this denial is the provider's responsibility to resolve. You cannot bill the patient for a CO-31 adjustment because the payer did not reject the service — they simply could not identify who the patient is. The fix is straightforward: verify the correct insurance details, update your records, and resubmit a clean claim. This is one of the most preventable denial codes, and high-volume practices that implement real-time eligibility checks at scheduling and check-in can virtually eliminate it.

Common Causes

How to Resolve

Verify the patient's insurance identifiers against the payer's records, correct any mismatches, and resubmit the claim.

1. Contact the payer for specifics Call the payer's provider services line and ask exactly why the patient cannot be identified. Request details on what data element is mismatched or whether there is a known enrollment system issue.
2. Verify COB order If the denial is on a secondary claim, confirm the coordination of benefits order with the patient and ensure the correct subscriber information was used for the secondary payer.
3. Request reprocessing or resubmit If the payer confirms an enrollment data issue on their end, ask them to reprocess the claim once corrected. If the COB order was wrong, redirect the claim to the correct payer.

How to Prevent OA-31

• Collect primary, secondary, and tertiary insurance details during registration and verify COB order with each payer before submitting claims
• For patients with new coverage, confirm enrollment has been loaded in the payer's system before filing claims by running a 270/271 check

General Prevention

• Collect and verify all insurance coverage details — primary, secondary, and tertiary — during patient registration to ensure correct COB sequencing
• Confirm with the payer that the patient's enrollment has been loaded before submitting claims for patients with brand-new coverage

Also Filed As

The same CARC 31 may appear with different Group Codes:

Related Denial Codes