CO-45 Denial — How to Appeal for Behavioral Health
CO-45 (charge exceeds fee schedule) is one of the most common insurance denial codes behavioral health therapists encounter. This guide explains what triggered the denial and the most effective appeal strategy across all major payers.
What CO-45 means
Your billed charge is higher than the maximum the payer allows for this service under the fee schedule. This is a contractual reduction — it is not a denial of the service, just a reduction to the contracted rate. No appeal is required unless you believe the fee schedule was applied incorrectly.
Appeal strategy for CO-45
Confirm the billed code was correct. If you believe the fee schedule rate was applied in error (wrong contract, wrong table year, out-of-network rate applied to an in-network claim), request the fee schedule documentation from the payer and compare against your contract. File a payment dispute with the contract reference if there is a discrepancy.
CPT codes commonly denied with CO-45
Appeal CO-45 by payer
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Generate my appeal letter →Frequently asked questions about CO-45
What does CO-45 mean on a behavioral health claim?
Your billed charge is higher than the maximum the payer allows for this service under the fee schedule. This is a contractual reduction — it is not a denial of the service, just a reduction to the contracted rate. No appeal is required unless you believe the fee schedule was applied incorrectly.
How do I appeal a CO-45 denial?
Confirm the billed code was correct. If you believe the fee schedule rate was applied in error (wrong contract, wrong table year, out-of-network rate applied to an in-network claim), request the fee schedule documentation from the payer and compare against your contract. File a payment dispute with the contract reference if there is a discrepancy.
Does MHPAEA apply to CO-45 denials?
CO-45 is a general adjudication code that typically applies equally to all claim types. MHPAEA may still be relevant if the payer applies the underlying rule differently to mental health services than to comparable medical/surgical services.
Which insurers most commonly issue a CO-45 denial?
All major commercial payers — Aetna, Cigna, Anthem, UnitedHealthcare, Humana, and BCBS plans — use CO-45. Government programs (Medicare, Medicaid, TRICARE) also issue this code. The appeal strategy is similar across payers, but deadlines and submission addresses vary. Select your payer from the list below for payer-specific instructions.