CO — Contractual obligation — the provider absorbs it and cannot bill the patient.
So the balance cannot move to the patient. Either the appeal recovers it or the practice absorbs it. That makes the appeal decision the whole decision on this line.
The same code, a different prefix. 26 also arrives as PR 26. The reason for the denial is the same. The prefix decides who pays for it, so the next step is not the same. If your remit says PR 26, read that page instead.
Usually lost. Recoverable only with unusual evidence. Triage by dollar value.
Re-verify, then rebill the correct payer or the patient.
Where this comes from. This is our own reading of the code, not the payer's and not a copy of the standards text. We classify it from how these denials actually resolve. Where we are unsure, we say so rather than guessing.
Send your denial summary for the last ninety days. Four columns: payer, CARC code, count, billed amount. I will tell you which were winnable and what they were worth.
Send your denial summary No patient data. No BAA. No charge.