Denial Code CO-97 — Bundling and Unbundling — What It Means and How to Challenge It

Denial Code CO-97 is a bundling denial. Often correctable with the right billing modifier. Here is how to challenge it.

[Alex Rivera

Appeals Specialist and Author](/team/claimcompass)

4

min. read

June 24, 2026

What Does Denial Code CO-97 Mean?

Denial code CO-97 means the insurer denied or reduced payment because the submitted service is already included in the payment for another service that was billed on the same claim. This is called bundling —the insurer is saying two separately billed procedures should have been billed as one.

CO-97 denials are technical. They typically do not involve a dispute about whether the services were medically necessary — only about how they were coded.

Why CO-97 Denials Are Sometimes Wrong

Incorrect application of bundling rules

Insurers and claims processors use Correct Coding Initiative (CCI) edits to determine which codes should be bundled. These edits are updated regularly and can be misapplied.

Modifier not appended

If two procedures were genuinely performed separately — at different anatomical sites, at different times, or requiring distinct skills — a modifier (such as Modifier 59 or XU) should have been appended to the claim to indicate they were distinct services. If the provider failed to append the modifier, this can be corrected and the claim resubmitted.

The procedures are not bundled under current coding guidelines

Bundling rules change. If the denial was based on outdated CCI edits or an incorrect interpretation of current guidelines, the denial can be challenged with current coding authority documentation.

How to Appeal a CO-97 Denial

Step 1 — Confirm with your provider

Ask the billing department to confirm whether the appropriate modifier was appended. If not, they can typically correct and resubmit the claim.

Step 2 — Request the specific CCI edit cited

Ask the insurer to identify the specific bundling edit that was applied. You or your provider can then verify whether that edit was applied correctly.

Step 3 — Document that the procedures were distinct

If the procedures were genuinely performed separately — different anatomical sites, different timing, or distinct clinical purposes — document this clearly in the appeal.

Step 4 — Cite current coding guidelines

Reference the current CPT coding guidelines and CCI edits that support billing the procedures separately.

How ClaimCompass Helps

ClaimCompass analyzes your CO-97 denial and generates anappeal letter addressing the specific bundling issue.

Upload your denial at myclaimcompass.ai for a free analysis.

Frequently Asked Questions

What is a billing modifier?

A modifier is a two-digit code appended to a CPT procedure code that tells the insurer additional information about the service — for example, that it was performed on a different anatomical site, at a different time, or by a different provider than another billed service.

Should I contact my provider first for a CO-97 denial?

Yes. CO-97 denials are often correctable at the billing level. Your provider's billing department can review the claim, append the correct modifier if applicable, and resubmit before a formal appeal is necessary.

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