What does CO-97 mean?

CO-97 is a Contractual Obligation (CO) denial: "The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated." This is a bundling denial — the payer says the service is already paid for as part of another code you billed, so it won't pay separately.

CO · Contractual ObligationCARC 97

Denial Code CO-97

Q: Is CO-97 the patient's responsibility or a provider write-off?

CO-97 carries the CO group code (Contractual Obligation): Provider/contractual responsibility — not billable to the patient while denied. A CO adjustment is the provider's responsibility, not the patient's: balance-billing the patient for a CO amount is a contract (and often compliance) violation. But CO does not automatically mean “write it off.” When the cause is fixable — missing information (CO-16), a modifier problem (CO-4), or NCCI bundling (CO-97) — you correct and resubmit, or appeal with documentation. You only truly write the amount off when it is a final contractual adjustment, such as the fee-schedule difference on CO-45.

The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.

Source: X12 Claim Adjustment Reason Codes (CARC) & Group Codes. Maintained by the D3rx Clinical Billing Team.

What CO-97 means

This is a bundling denial — the payer says the service is already paid for as part of another code you billed, so it won't pay separately.

Got this denial right now?

Fix & resubmit: see the CO-97 correction steps

See CO-97 correction steps Ask D3 about CO-97

CO-97 clears with a corrected claim, not an appeal. Ask D3 walks you through the exact fix — free, no signup.

CO group code: who absorbs the charge

Contractual Obligation — Provider/contractual responsibility — not billable to the patient while denied.

A CO adjustment is the provider's responsibility, not the patient's: balance-billing the patient for a CO amount is a contract (and often compliance) violation. But CO does not automatically mean “write it off.” When the cause is fixable — missing information (CO-16), a modifier problem (CO-4), or NCCI bundling (CO-97) — you correct and resubmit, or appeal with documentation. You only truly write the amount off when it is a final contractual adjustment, such as the fee-schedule difference on CO-45.

Why CO-97 happens

An NCCI (Correct Coding Initiative) edit pair was billed without the required modifier
A component/incidental service was billed alongside the comprehensive procedure that includes it
A code that is always bundled into the primary service was reported separately
Two services that overlap were billed without documentation of a distinct service

What to do when you get CO-97

1Look up the NCCI edit for the code pair and check the modifier indicator
2If the modifier indicator is 1 and the services were truly distinct, append the most specific NCCI-associated modifier (prefer XE/XS/XP/XU; use 59 only when none is more specific) and resubmit
3If the modifier indicator is 0, the pair cannot be unbundled — the Column 2 (component) code is not separately payable and is written off
4Confirm documentation supports a separate site, session, or encounter before unbundling

Appeal, correct, or write off CO-97?

CO-97 turns on the NCCI modifier indicator. If the indicator is 1 and your documentation supports a separate/distinct service, append the most specific X{EPSU} modifier (use 59 only when none fits better) and submit a corrected claim — this is the common, legitimate fix. If the indicator is 0, the bundle is absolute: the Column 2 component code is written off rather than appealed. Only appeal an indicator-1 pair when a modifier was already correctly applied and the payer still bundled it; attach the note proving the distinct service.

Timing & deadlines

Submit the corrected claim within the payer's timely-filing limit (Medicare 12 months from date of service; commercial ~90-180 days). If appealing, use the standard windows (Medicare 120 days; commercial ~180 days from the remittance).

Example

A surgeon bills a lesion excision and a separate biopsy of a different lesion at a distinct site on the same day. Because the biopsy is bundled into the excision under NCCI (indicator 1), the payer returns CO-97. Appending modifier 59 (or XS for separate structure) to the biopsy, supported by the op note documenting the distinct lesion, allows separate payment.

Prevent CO-97 going forward

Run NCCI edits in your claim scrubber before submission
Reserve modifier 59 / X{EPSU} for genuinely distinct services and document them
Know which incidental codes are always bundled into your common procedures
Audit modifier-59 usage to avoid both bundling denials and overuse flags

Code families most affected

Surgery code pairs subject to NCCI edits
Lab panels vs. component tests (e.g., 80053 vs. individual chemistries)
80053
Procedures with bundled incidental/add-on services
Same-day E/M plus procedure combinations

Related codes

Denial codes you'll often see alongside CO-97

CO-4 CO-45 CO-50

Modifiers tied to fixing CO-97

Modifier 59 Modifier XE Modifier XS Modifier XP Modifier XU Modifier 25

Payer notes

CO-97 is rooted in NCCI Procedure-to-Procedure edits, which most payers adopt, but commercial payers may bundle pairs Medicare doesn't (and vice versa). The modifier indicator (0 = never unbundle, 1 = unbundle with a supported modifier) is the decisive fact; never append modifier 59 without documentation of a truly separate service.

Fix this CO-97 denial the right way

CO-97 is resolved with a corrected claim, not an appeal. Ask D3 gives you the exact correction steps — free, backed by CMS, Medicare, and major-payer data.

See CO-97 correction steps Ask D3 about CO-97 All denial codes

Medical billing disclaimer

CARC/RARC definitions are the standardized X12 set; group-code semantics follow the X12 Claim Adjustment Group Code standard. Filing and appeal windows vary by payer — the standard anchors shown (Medicare redetermination 120 days from the remittance; Medicare timely filing 12 months from date of service; most commercial payers ~90-180 days) are general references, not a guarantee for any specific plan. Always confirm the rule in the payer's provider manual before acting. D3rx is not responsible for claim outcomes.