CO-97

CO-97 is one of the most misunderstood denial codes in medical billing, because it often looks like an error when it’s actually the system working exactly as designed. Understanding when CO-97 is correct — and when it’s worth fighting — can recover revenue that most billing teams write off by default.

What CO-97 Means

CO-97 stands for “The benefit for this service is included in the payment/allowance for another service that has already been adjudicated.” In plain terms: the payer has decided this procedure shouldn’t be paid separately because it’s considered part of another service already billed on the same claim or same date.

This is almost always tied to NCCI (National Correct Coding Initiative) edits — a set of rules maintained by CMS that define which CPT/HCPCS code pairs shouldn’t normally be billed together.

Why CO-97 Happens

Column 1/Column 2 NCCI edits. CMS maintains edit pairs where one code (Column 2) is considered a component of another (Column 1) and shouldn’t be separately reimbursed under normal circumstances.

Mutually exclusive procedures. Some code pairs represent two different ways of performing the same service — billing both suggests one was likely unnecessary or redundant.

Global surgical package bundling. Follow-up visits or minor procedures performed within a surgery’s global period are often bundled into the original procedure’s payment, even when billed as separate line items.

Same-day service bundling. Multiple services performed during the same encounter can trigger bundling edits even when clinically they were genuinely separate and distinct.

When CO-97 Is Correct (Don’t Appeal)

If the NCCI edit reflects a genuine component relationship — for example, a supply that’s inherently part of a procedure — the denial is accurate, and the correct action is to write off the amount as a bundling adjustment, not appeal it.

When CO-97 Is Worth Appealing

The services were genuinely separate and distinct. If two procedures were performed at different sites, through different incisions, or represent clinically unrelated work during the same visit, an appeal with modifier correction may be appropriate.

Modifier 59 (or X-modifiers) applies. When services are distinct, appending modifier 59 (or the more specific XE, XS, XP, XU modifiers CMS now prefers) signals to the payer that the NCCI edit shouldn’t apply in this specific case. This must be supported by documentation, not applied automatically to bypass edits.

The edit doesn’t actually apply to this code pair. NCCI edits update quarterly. It’s worth double-checking the current edit table, since edits are occasionally removed or narrowed in scope.

How to Build the Appeal

Step 1: Verify the NCCI edit status

Check the current NCCI Procedure-to-Procedure (PTP) edit file for the specific code pair. Confirm whether it’s flagged as “0” (never bypass), “1” (can bypass with appropriate modifier), or “9” (edit doesn’t apply).

Step 2: Confirm clinical distinctness

Review the operative or clinical notes to confirm the services were performed at separate sites, separate sessions, or represent genuinely unrelated work — not just two codes that happen to describe related anatomy.

Step 3: Apply the correct modifier and resubmit

If the edit allows a bypass modifier and documentation supports it, correct the claim with the appropriate modifier and resubmit rather than filing a lengthy appeal — this is often faster than the formal appeals process.

Step 4: If already denied, appeal with the modifier and documentation attached

Include the specific clinical documentation that demonstrates distinctness, along with a brief explanation referencing the NCCI edit indicator that permits the bypass.

The Pattern Worth Watching

If CO-97 shows up frequently for the same code pairs, it’s worth building a simple internal reference: which combinations are legitimately bundled (write off and move on) versus which ones represent a recurring coding or modifier training gap (fixable at the source).

Search the CARC/RARC Lookup Tool for other bundling-related codes you’re encountering, or use the Denial Cost Calculator to see how much revenue recurring bundling denials are actually costing your practice.