CO-97 denial code
The service is considered already paid for as part of another service on the same claim. This is bundling: the payer says you billed separately for something that was included in the price of something else.
CO — Contractual Obligation. The write-off is yours. You agreed to it in your contract with the payer, and you cannot bill the patient for it.
Why you got it
- 1The two procedures are bundled under a payer edit — the second is treated as a component of the first.
- 2The service falls inside another procedure's global surgical period.
- 3A modifier that would have made the second service separately payable was missing, or was not supported by the documentation.
- 4The same service was billed twice, once bundled into a comprehensive code and once on its own.
How do I fix a CO-97 denial?
- Check whether an unbundling modifier legitimately applies. If it does, and the documentation genuinely supports a distinct service, append it and resubmit.
- Do not simply add a modifier to force payment. An unsupported modifier is what a payer audit looks for, and it converts a denial into a repayment demand.
- If the service really is bundled, write it off. Appealing a correct bundling edit wastes more than it recovers.
How to stop the next one
Bundling is decided by procedure-to-procedure edits, which are published quarterly. Checking the pair before submission is a two-second operation; discovering it on the remit costs a rework cycle.
Our diagnosis scrubber will not catch this one. CO-97 is driven by procedure codes, modifiers, or eligibility rather than by the diagnosis set — and procedure-side checking needs an AMA CPT licence we do not hold yet. We would rather tell you that than sell you a tool that quietly misses your most common denial.
If denials like this are a volume problem rather than a one-off, the denial management page explains how the paid workspace catches the coding causes on every claim, and the free ICD-10-CM lookup shows the coding notes behind any diagnosis code on the remittance.