CO-97 denial code
The benefit for this service is included in the payment for another service already adjudicated
How to fix it
Determine whether the services were genuinely separate. If so, appeal with documentation supporting an appropriate modifier such as 25, 59 or an X modifier. If bundling is correct, adjust.
How to prevent it
Run NCCI edits during scrubbing and apply global period logic so bundled services are not billed separately.
In practice
A patient attends for a scheduled lesion excision. The physician also performs a brief evaluation before the procedure and the practice bills an office visit alongside the excision. The remittance returns CO-97 against the office visit line.
The question to answer is whether the evaluation was genuinely separate from the pre-service work the excision already includes. Every procedure carries an inherent evaluation component — assessing the site, confirming the plan, obtaining consent — and that work is inside the procedure's value.
If the note shows only that assessment, the bundling is correct and the line adjusts. If the patient was separately evaluated for an unrelated complaint, the E/M is billable with modifier 25 and the appeal should attach the note showing the separate history, examination and decision-making.
What sits behind it
CO-97 is generated by two distinct mechanisms that require different responses. The first is an NCCI procedure-to-procedure edit, where two codes billed together are considered one service. The second is global period inclusion, where a service falls inside the 10 or 90-day window following a surgical procedure.
Distinguishing them matters because the fix differs. An NCCI edit may be overridden with an appropriate modifier where the services were genuinely distinct. A global period inclusion generally requires a different modifier entirely — 24 for an unrelated E/M during the postoperative period, or 79 for an unrelated procedure.
Applying modifier 59 reflexively to clear CO-97 is the error that turns a recoverable denial into an audit finding. The X modifiers — XE, XS, XP, XU — are more specific and are preferred where they apply, because each states why the services were distinct rather than merely asserting that they were.
Related codes
Terms used here — NCCI Edits · Modifier · Denial
How we handle it — Denial Management · Medical Coding · Claims Management
Primary sources
The rules behind CO-97, at the bodies that publish them.
- NCCI Policy Manual for Medicare Services (opens in a new tab)
Centers for Medicare & Medicaid Services — The reasoning behind the edits, chapter by chapter. Where the edit files tell you two codes conflict, this explains why — which is what an appeal has to address.
- National Correct Coding Initiative (NCCI) edits (opens in a new tab)
Centers for Medicare & Medicaid Services — The procedure-to-procedure and medically-unlikely edits behind most bundling denials. Checking these before submission prevents the denial entirely.
- Global Surgery booklet (opens in a new tab)
Centers for Medicare & Medicaid Services — What the 10 and 90-day global periods include, and which modifiers break out of them. The authority behind most postoperative bundling disputes.
Every denial code with a guide
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Questions about CO-97
Yes, when the services were genuinely separate. The appeal has to attach documentation supporting the distinction — a separate site, a separate session, or a separately identifiable evaluation — and the appropriate modifier. Where the bundling reflects a correctly applied NCCI edit or global period inclusion, there is nothing to appeal and the line adjusts.
CO-97 means the service was bundled into another already adjudicated. CO-B15 means a required qualifying service was not billed or not paid — the payer expected a prerequisite procedure it did not receive. CO-97 asks whether the services were separate; CO-B15 asks whether something is missing.
It depends on why it fired. For an NCCI edit with genuinely distinct services, modifier 59 or the more specific X modifiers — XE, XS, XP, XU. For a significant, separately identifiable E/M on the day of a procedure, modifier 25. For an unrelated service inside a global period, modifier 24 or 79. Using 59 reflexively is a common audit finding.
No. The CO prefix indicates a contractual obligation, which means the provider absorbs the adjustment under the payer agreement. The balance cannot be transferred to the patient.
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