The Psychiatric Diagnostic Evaluation is the gateway to a new patient relationship. It's a comprehensive, one-time (per episode of care) service, and billing it incorrectly starts the entire revenue cycle off on the wrong foot. The key is knowing which code to use: 90791 or 90792.
90791 vs. 90792: Who Bills What?
CPT 90791 (Psychiatric diagnostic evaluation):
- Used by non-prescribing providers (e.g., LCSWs, PhDs, PsyDs, LPCs).
- Includes a chief complaint, psychosocial history, mental status exam, and initial treatment plan.
CPT 90792 (Psychiatric diagnostic evaluation with medical services):
- Used by prescribing providers (e.g., MDs, DOs, NPs, PAs).
- Includes all elements of 90791 plus a medical history and review of systems.
Key Billing Rules
- Once Per Episode: You generally only bill 90791 or 90792 once at the beginning of a new treatment episode.
- No Same-Day E/M: You cannot bill an E/M code (like 99204) on the same day as 90792. The evaluation is all-inclusive.
- No Same-Day Psychotherapy: You cannot bill a psychotherapy code (like 90834) on the same day as 90791. The intake is a diagnostic service, not a therapy session.
The "New Patient" Trap
"90791 is not a 'new patient' code, it's an 'intake' code. A patient can be 'established' at your clinic but see a new therapist for a new episode of care (e.g., new diagnosis, 6 months after discharge). This would justify a new 90791."
