EOB denial code CO-31: what it means

What it means

The insurer could not match you to an active policy with the information on the claim.

Contractual Obligation — an adjustment the provider agreed to by contract. The patient is generally not billed for CO amounts.

Official X12 description

“Patient cannot be identified as our insured”

Typical cause

A wrong or mistyped member ID, name, or date of birth — or the claim was sent to the wrong insurer.

What to do next

1. 1Give your provider's billing office your exact member ID and name as printed on your insurance card.
2. 2Confirm the claim was sent to the correct insurer.
3. 3Ask for a corrected claim to be resubmitted.