Denial codes / CO-31

Denial code 31

CO-31: Patient not found as a member

Patient cannot be identified as the insurer's member.

What to doCheck coverage, then resend
Often recoverableYes, when worked

The letters in front matter. CO means the office can't bill the patient for the amount; PR means the patient may owe it. The same number can appear with either, so read both parts.

Why dental offices see it

  • Wrong member ID, name spelling or date of birth.
  • The patient is a dependent and was billed as the subscriber.
  • The plan uses a different ID than the card shows.

What to do

  1. Compare the claim with the insurance card and the eligibility response.
  2. Correct the subscriber and patient details.
  3. Resend as a corrected claim.

Stop it next time

Scan the card and run eligibility at check-in; copy the ID exactly.

How many CO-31 claims are in your report? The free check counts them, ranks them by dollars and deadline and drafts the letter. It runs in your browser; nothing is uploaded.

Run the free check

Plain-English paraphrase; the official code list is maintained by X12. Insurer rules vary; check the insurer's provider manual. Not legal advice.