CO-31 denial code: patient cannot be identified as our insured

Claim adjustment reason code 31 says: patient cannot be identified as our insured. The payer searched its records with the details on the claim and found no matching member.

With group code CO, the patient can't be billed for it yet. The claim needs the right details, or the right payer.

• The member ID is wrong: a typo, a missing prefix, or the subscriber's number used for a dependent.
• An old Medicare number. Medicare replaced Social Security-based numbers with the Medicare Beneficiary Identifier (MBI). Claims need the MBI.
• The claim went to the wrong payer, such as Original Medicare for a patient in a Medicare Advantage plan. See CO-24 and CO-109.
• The patient's name or date of birth doesn't match the payer's record, for example after a name change.
• The patient wasn't enrolled yet, or had left the plan.

1. Check the patient's card and compare the member ID, name and date of birth with the claim.
2. Verify eligibility with the payer using the card's details, and note exactly how the payer's record shows the patient.
3. Confirm you billed the right payer, especially for Medicare patients.
4. Correct and resubmit, within the timely filing limit.

• Scan the card at every visit, front and back.
• Verify eligibility with the payer before the visit, and copy the patient's details exactly as the payer has them.
• Use the MBI for Medicare patients, and ask about Medicare Advantage enrollment.

CO-31 is decided by the patient's details and coverage, so it is prevented at booking.

Claira Health's AI agents confirm coverage and the right payer before the visit, so this denial is stopped at the front desk instead of coming back weeks later. Your team sees only what needs a decision, and approves every step. On a 20-minute call, we’ll walk through it using one of your own denials.

Related: CO-140, name and ID don't match. Book a 20-minute call to see your front-desk denials.