How do you fix CO-97 bundled service denials?

How do you find the line that absorbed the denied service?

Look on the remittance for the service that was priced with an allowed amount on the same date, for the same patient and provider. CARC 97 says the benefit is included in the payment for another service that has already been adjudicated, so the answer is on the paid line and not on the denied one. The CO-97 code page has the X12 wording.

Write the pair on the account: the denied code and the code that absorbed it. Without the pair you cannot look up the edit, and you cannot tell the next person why the line was written off.

Then read the remark code, because it narrows the cause. M15 says separately billed services were bundled as components of the same procedure. N20 says the service is not payable with another service on the same date. N525 points to a global period. N657 says to bill with the appropriate code, which is a coding choice and not a bundle.

Which cause applies: an NCCI edit, a global period or packaging?

Each cause has a different test and a different outcome, so decide before you act. Treating all CO-97 lines as modifier problems is how groups end up adding modifiers they cannot support.

The NCCI edits page explains how the PTP edits are built. For professional claims, the 2026 NCCI Policy Manual, chapter 1, says providers must report the most comprehensive code that describes the service and must not unbundle.

Does the chart support a separate service?

A modifier is justified only when the record shows something the edit did not see. The NCCI manual says that in general those circumstances are separate patient encounters, separate anatomic sites or separate specimens, and that a modifier is never appended solely to bypass an edit.

• Separate encounter: the visit or session is documented at a different time, not as one block with the first service.
• Separate site: the procedure is on a different anatomic site, and the note names both. Contiguous structures count as one site.
• Separate specimen: the specimens are labelled and documented as different.
• Different diagnoses alone are not enough. CMS's MLN guide on modifier 59 says they are not adequate criteria.

Modifiers 22, 76 and 77 do not bypass an edit, and a pair with a modifier indicator of 0 cannot be bypassed with any modifier. An indicator of 1 allows a modifier under appropriate circumstances, and 9 means the indicator is not specified. When an edit allows it, modifier 59 is for distinct procedures, and CMS says to use the more specific X modifiers (XE, XS, XP, XU) whenever possible. Modifier 25 is for a significant, separately identifiable E/M service on the day of a procedure, and the E/M and the procedure must both be documented.

How do you resubmit the claim with the right modifier?

The documentation requirement is real even though it is not sent with the claim. The 2026 NCCI manual says the documentation must support the criteria for the modifier.

Should you ask for a reopening or a redetermination?

For Medicare, a forgotten or wrong modifier is a clerical error and goes through a reopening, which can be requested within 1 year of the initial determination for any reason under 42 CFR 405.980(c). A disagreement over coding judgment goes to a redetermination, due within 120 calendar days of receiving the notice under 42 CFR 405.942.

Claims Processing Manual chapter 34, section 10.4, lists use of a modifier among the incorrect data items treated as clerical errors. Once a valid appeal is filed on an issue, a contractor cannot reopen the same issue, so choose one route. The Medicare appeal levels page covers the full sequence.

Other payers set their own routes in the manual, so confirm the terms there before you choose.

When is the bundle correct and the write-off stands?

The bundle stands when the chart shows one encounter, one site and one specimen, or when the line is packaged. A CO group code means the amount is the provider's, so post a contractual adjustment and do not bill the patient.

On hospital outpatient claims, keep reporting the packaged charge. Chapter 4, section 10.4, says the charges for unconditionally packaged services are used to calculate outlier payments and future rates. A packaged line is not an error to remove, and it is not a denial to chase.

How do you stop the same bundle from coming back?

• Run the claim against the edit pair at charge entry, not after the denial.
• Make the coder record the chart evidence for any modifier on the line, one sentence long.
• Count CO-97 by code pair every month, so one repeat pair becomes a coding rule.
• Put payer-specific bundling rules from the payer's manual in the same list, with the date you read them.

The broader method is in how to reduce claim denials, and the cardiology billing page covers the codes that bundle most often in that specialty.

How does Nucleus Align handle CO-97 denials?

Our coders, who hold AAPC and AHIMA certifications, read the chart against the edit before a modifier goes on, and our claim scrubbing rules check bundles before submission. Denials are worked within 48 hours.

See our denial management service, or book a call to review a set of CO-97 denials.