CO-45: Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.
The payer is telling you the billed charge is higher than the amount their fee schedule or contract allows for this service. The difference between what you billed and what the payer allows becomes a contractual write off, not something you can bill the patient for when an in network contract is in place.
What the group code means
- CO
- Contractual Obligation. The provider is responsible and the amount cannot be billed to the patient.
Why it fires
- Billed charge exceeds the payer's fee schedule or contracted rate for the CPT/HCPCS code
- No modifier or documentation was included that could justify an exception to the fee schedule
- Fee schedule updated on the payer side (annual CMS or payer update) and the practice's charge master was not
Corrective actions, ranked
- 1
Verify the contract rate
Pull the current fee schedule or contract rate sheet for this payer and CPT code and confirm the allowed amount matches what was paid.
- 2
Write off per contract
If the allowed amount is correct per contract, adjust off the difference. This is a standard contractual adjustment, not an error.
- 3
Check for a fee schedule update lag
If the payer recently updated its fee schedule, confirm the correct effective date was applied to this date of service.
Is it worth appealing
Appeal only if you can show the payer used the wrong fee schedule, wrong contract year, or the code is not actually subject to that schedule. Otherwise this is a routine contractual write off and not appealable.
Other denial codes to check
Codes that share a remark code with this one, or that are reported under the same group code.
- CO-97The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.
- CO-16Claim/service lacks information or has submission/billing error(s).
- CO-11The diagnosis is inconsistent with the procedure.
- OA-18Exact duplicate claim/service (Use only with Group Code OA except where state workers' compensation regulations requires CO)
- CO-29The time limit for filing has expired.
- PR-151Payment adjusted because the payer deems the information submitted does not support this many/frequency of services.
Retrieved 2026-07-18.
Do not let this happen again
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Denial7 provides billing and administrative guidance based on published CMS and X12 sources. It is not medical advice, not a coverage determination, and not a guarantee of payment. NCCI and MUE edits are republished quarterly and payer policies vary by contract. Always confirm against the payer's own current policy before submitting or appealing.