There are two codes for psychiatric diagnostic evaluation.

90791 Psychiatric diagnostic evaluation
90792 Psychiatric diagnostic evaluation with medical services

90791 is used by psychologists, social workers and other licensed behavioral health professional and 90792 is used by psychiatrists and psychiatric nurse practitioners and physician assistants, because it includes medical services. Here is how CPT^® defines those services,

“Psychiatric diagnostic evaluation is an integrated biopsychosocial assessment, including history, mental status, and recommendations. The evaluation may include communication with family or other sources and review and ordering of diagnostic studies.

Psychiatric diagnostic evaluation with medical services is an integrated biopsychosocial and medical assessment, including history, mental status, other physical examination elements as indicated, and recommendations. The evaluation may include communication with family or other sources, prescription of medications, and review and ordering of laboratory or other diagnostic studies.” CPT Professional Ed. 2025, AMA, Chicago, page p. 766