RemitBench/Denial codes/CO-31

CO-31 denial code

Code 31 is not about the service at all. The payer looked for this person in its records and did not find them. Until that is fixed nothing else on the claim matters.

The code list's own wording: Patient cannot be identified as our insured.

Why the payer sent it

• A wrong or transposed character in the member identification number.
• The name on the claim does not match the name on the policy. Married names, hyphenated names and shortened first names are the usual cause.
• The date of birth does not match.
• The patient is a dependent and was billed under their own name where the payer files them under the subscriber.
• The card is out of date and the patient has moved plans.
• The claim went to the wrong payer entirely, which is really CO-109.

Remark codes you will see with it

Read the letters in front of the 31

What to do next

1. Read the card again, character by character

   Member ID, full legal name, date of birth. Compare against what went out on the claim rather than against what is in your patient record, because those can differ.

2. Check whether the patient is a dependent

   Many payers file dependents under the subscriber's identifier. Billing a child under their own number produces this every time.

3. Run an eligibility check for the date of service

   That answers the real question: does this payer cover this person on that date. It is faster than a phone call and it tells you whether to fix the claim or find another payer.

   If eligibility comes back clean: your data is wrong somewhere. Compare field by field. If it comes back with nothing: ask the patient for their current card, because they have probably changed plans.

4. Only talk about self pay when you are certain

   After the eligibility check, not before. And even then, ask what coverage they had on the day rather than assuming there was none.

Codes that get mixed up with 31

The useful split: 31 means the payer found nobody. 26, 27 and 32 all mean the payer found the person and had something else to say about them.

Code 31 in dental

Dental offices see this more than medical offices do, for one structural reason: dental benefits are often carried by a different company from the medical plan, and patients bring the card they carry rather than the one you need.

The wrong card is the most common cause

A patient hands over the medical card because that is the one in their wallet. The dental plan is administered elsewhere, often under a different member number. Asking specifically for the dental card at check in removes a large share of these before they happen.

Children on two plans

A child covered by both parents is filed under two subscribers, and which one is primary follows a rule the family does not know. Billing under the wrong subscriber produces a 31 or a CO-22, depending on the payer.

Questions people ask about CO-31

Does CO-31 mean the patient has no insurance?

No. It means the payer could not match the identifying details on the claim to anyone in its records. A transposed digit in the member number or a name that does not match the policy produces exactly this. Run an eligibility check for the date of service before you say anything to the patient.

Can I bill the patient for a CO-31?

Not until you have established there was no coverage on that date. The claim was never adjudicated, so nothing has been decided about who owes what.

Related codes

• CO-140 The identification number and name do not match.
• PR-26 Coverage had not started yet.
• PR-27 Coverage had ended.
• CO-109 Wrong payer entirely.
• CO-22 Another payer may be primary.

Back to all denial codes