The procedure code and the modifier do not agree.
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.
Fix and resubmit. This is a correction, not an appeal. Appealing burns the deadline.
In the order we see it.
The modifier is missing, invalid, or inconsistent with the procedure.
Fix the modifier and resubmit.
The documentation, not the argument.
The correct modifier, supported by the documentation.
The common mistake. Do not appeal a modifier problem. Correct and resubmit.
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.