Denial code · group CO
CO-97: The payer treats this line as already paid for through another service it processed
Short answer
CO-97 means the payer bundled this line into another service it already paid, under NCCI edits, a global surgical package, a place-of-service rule or its own bundling policy. When the two services were distinct and the record shows it, a corrected claim with the right modifier (59, an X modifier, 25 or 24) gets it paid. When they were not, the line is a contractual write-off; the patient is never billed.
Look up other codes in the denial code library.
Last reviewed by the Remitwright billing team. Editorial policy
Group CO means contractual obligation: the balance is written off, not billed to the patient. The number is the reason; the two-letter group says who carries the balance.
Remark codes that usually come with CO-97
- M15
- The payer sees these lines as parts of a single procedure, so none of them is paid on its own
- N19
- The payer treats this code as a minor part of the main procedure, so it earns no separate payment
- N20
- The payer will not pay this line alongside the other service billed for that day
- M144
- Care before and after the operation was paid as part of the surgical fee
- M97
- In this setting the facility's payment covers the service, so the practitioner gets nothing extra for it
Common causes
An NCCI procedure-to-procedure edit
CMS publishes the National Correct Coding Initiative edits to prevent improper payment when code combinations that should not be billed together are reported, and updates the files quarterly. Two codes that NCCI pairs, billed on the same date without an allowed modifier, deny the secondary code. Depending on the payer, that denial arrives as CO-97, the general bundling code, or as CO-236, the code X12 defines around NCCI; the work is the same. Commercial payers and Medicaid plans apply the same tables or their own versions.
A visit inside the global surgical period
An evaluation and management code billed during the post-operative period of a procedure, by the same provider or group, is treated as part of the surgical payment. M144 is the remark. A visit for an unrelated problem can be paid, but only with the modifier that says so.
Same-day visit and procedure without modifier 25
A visit billed with a minor procedure on the same day is bundled unless the visit was significant and separately identifiable and carries modifier 25. If the visit was only the decision to do the procedure, it is bundled correctly.
Place-of-service bundling
Supplies, drugs or technical components billed by the practitioner for a service performed in a facility are paid to the facility. M97 names it. The practitioner's claim should carry only the professional work.
The payer's own bundling policy
Commercial payers run edits that go beyond NCCI: supplies included in visit codes, certain tests folded into panels, therapy codes bundled with evaluation codes. The policy lives in the payer's reimbursement policy library, and the contract says whether it may go beyond NCCI.
A component billed with its own full code
A service that is defined as a part of another, billed as if it stood alone. N19 flags it as a minor part of the main procedure. There is no modifier for this; the line is simply not separately payable.
How to fix it and resubmit
- 1
Identify the edit that fired
Look the two codes up in the NCCI PTP table for the quarter that covers the date of service, and check whether the pair appears and whether a modifier is permitted for it. For a global period denial, check the procedure's global days and the date of the visit. For a payer policy, find the reimbursement policy page. The remark code tells you which search to run.
- 2
Check the record for a distinct service
A modifier is only correct when the documentation shows separate anatomic sites, separate sessions or encounters, a different problem addressed at a separate visit, or care unrelated to the surgery. If the record supports it, the coder picks the modifier: 59 or the X modifier that fits, 25 for the visit, 24 for an unrelated post-operative visit, 79 for an unrelated procedure.
- 3
Corrected claim with the modifier
Resubmit the denied line with frequency code 7 and the original claim number. Expect a records request on 25 and 59 lines from payers that review them; have the note ready.
- 4
Appeal when the payer's edit goes beyond your contract
If your agreement says NCCI governs and the payer applied a stricter bundling policy, appeal with the contract clause and the NCCI table showing the pair is not an edit. If the contract lets the payer apply its own policies, the denial stands.
- 5
Write off a true bundle
When the services were components of one procedure, post the CO-97 as a contractual adjustment and remove the code from the charge template for that procedure. Do not bill the patient; the group code CO means the balance is yours.
How to prevent it
- A scrubber loaded with the current quarter's NCCI PTP tables and each payer's bundling policies, refreshed when CMS posts the quarterly files
- Charge templates that leave out supplies and components the payer bundles, built per payer and per place of service
- Global period tracking in the practice management system so post-operative visits are coded with 24 or 79 only when the documentation supports them
- Coder review of every 25 and 59 modifier before release, with the documentation that supports the separate service
A CO-97 on a same-day visit and laceration repair
An urgent care treats a patient for a cut on the hand and bills a problem-focused visit code plus the laceration repair code. The payer pays the repair and denies the visit CO-97. The biller reads the note. The clinician also evaluated an asthma flare, listened to the chest, changed the inhaler and documented the plan, which is a separate problem with its own work. The coder adds modifier 25 to the visit and the practice resubmits with frequency code 7. The visit pays. On a different chart where the visit covered only the cut, the same denial would stand and the visit would be written off. This is a hypothetical example.
Official text: the X12 claim adjustment reason code list. The meaning above is our paraphrase for billers; the list is the authority.
FAQ
Questions about CO-97
Is CO-97 a denial or an adjustment?
Can I bill the patient for a bundled service?
Which modifier fixes CO-97?
How often do NCCI edits change?
Why does a commercial payer bundle something NCCI does not?
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