CO-167 Denial — How to Appeal for Behavioral Health
CO-167 (diagnosis not covered) 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-167 means
The payer is saying the diagnosis code you submitted is not covered under the patient's plan. In behavioral health, this often surfaces as an exclusion for certain mental health diagnoses (e.g. adjustment disorder, V-codes, or substance use) that would not be excluded if they were medical diagnoses.
MHPAEA Mental Health Parity Argument
Selectively excluding mental health diagnoses that would be covered if they were medical diagnoses is a non-quantitative treatment limitation (NQTL) under MHPAEA — the payer cannot exclude a behavioral diagnosis without a comparable exclusion for similar medical diagnoses. Demand the CAA 2021 § 203 NQTL comparative analysis in writing; that statutory disclosure duty applies regardless of the 2025 federal non-enforcement of the 2024 Final Rule.
Request your payer's written Non-Quantitative Treatment Limitation (NQTL) comparative analysis. They are required to provide it under CAA 2021 § 203.
Appeal strategy for CO-167
Review the plan's covered diagnoses list and compare the mental health exclusions against any exclusions applied to analogous medical diagnoses. If the exclusion is diagnosis-specific for mental health only, invoke MHPAEA: excluding a mental health diagnosis that would be covered if it were a medical diagnosis violates parity. Also verify whether the ACA essential health benefit (EHB) mandate covers this diagnosis.
CPT codes commonly denied with CO-167
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What does CO-167 mean on a behavioral health claim?
The payer is saying the diagnosis code you submitted is not covered under the patient's plan. In behavioral health, this often surfaces as an exclusion for certain mental health diagnoses (e.g. adjustment disorder, V-codes, or substance use) that would not be excluded if they were medical diagnoses.
How do I appeal a CO-167 denial?
Review the plan's covered diagnoses list and compare the mental health exclusions against any exclusions applied to analogous medical diagnoses. If the exclusion is diagnosis-specific for mental health only, invoke MHPAEA: excluding a mental health diagnosis that would be covered if it were a medical diagnosis violates parity. Also verify whether the ACA essential health benefit (EHB) mandate covers this diagnosis.
Does MHPAEA apply to CO-167 denials?
Yes. Selectively excluding mental health diagnoses that would be covered if they were medical diagnoses is a non-quantitative treatment limitation (NQTL) under MHPAEA — the payer cannot exclude a behavioral diagnosis without a comparable exclusion for similar medical diagnoses. Demand the CAA 2021 § 203 NQTL comparative analysis in writing; that statutory disclosure duty applies regardless of the 2025 federal non-enforcement of the 2024 Final Rule. Request the payer's written Non-Quantitative Treatment Limitation (NQTL) comparative analysis under CAA 2021 § 203 — that statutory disclosure duty applies regardless of the 2025 federal non-enforcement of the 2024 Final Rule.
Which insurers most commonly issue a CO-167 denial?
All major commercial payers — Aetna, Cigna, Anthem, UnitedHealthcare, Humana, and BCBS plans — use CO-167. 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.