ICD-10 Diagnosis Code

The International Classification of Diseases, 10th Revision (ICD-10-CM) codes document the patient's diagnosis on a claim. Behavioral health ICD-10 codes fall primarily in the F00–F99 (Mental, Behavioral, and Neurodevelopmental disorders) chapter. The diagnosis must be specific enough to medically justify the CPT code billed — a CO-11 denial (diagnosis inconsistent with procedure) typically means the code is too unspecified or does not map to the service type.