Denial code

CO 109

Wrong payer or wrong contractor for this claim.

Fix and resubmit CO OA 109

What CO 109 means

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. 109 also arrives as OA 109. 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 OA 109, read that page instead.

Is it worth appealing?

Fix and resubmit. This is a correction, not an appeal. Appealing burns the deadline.

Why it fires

In the order we see it.

  1. The claim went to the wrong payer or the wrong contractor.

  2. A Medicare Advantage patient was billed to traditional Medicare.

What to do

Identify the correct payer and rebill.

What actually wins it

The documentation, not the argument.

Identification of the correct payer, and a rebill to them.

The common mistake. Do not appeal. Find the right payer and rebill, watching the new payer's filing window.

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.

Related codes

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