2026 ICD-10-CM Diagnosis Code F21

Code attributes

• Non-billable/Non-specific code

Coding rules

• Specify the leaf code — the parent code (e.g. F32) is a navigational header; billing requires a leaf code (F32.0, F32.1, etc.) that matches the documented presentation.
• Document onset, course, and severity (mild / moderate / severe) plus functional impact. Payers use this combination when adjudicating medical necessity.
• Attach a validated instrument score (PHQ-9, GAD-7, PCL-5, or equivalent) at intake and at follow-up where applicable. Objective measures support code selection and continued authorization.
• Review at every visit and update if presentation changes — including remission and partial remission states.

Clinical information

F21 covers schizotypal disorder — a pattern of social and interpersonal deficits with cognitive and perceptual distortions and eccentricities of behavior, but without the threshold psychotic episodes that would warrant a schizophrenia diagnosis. Document magical thinking, odd beliefs, unusual perceptual experiences, and social anxiety that persists despite familiarity.