CPT Code 90791: Psychiatric Diagnostic Evaluation

As one of the CPT codes in the psychiatry category, 90791 reports a psychiatric diagnostic evaluation without medical services and covers: 

• History gathering
• Initial clinical interview
• Diagnostic formulation
• Mental status examination

… that produce a psychiatric diagnosis and treatment recommendation. 

The code carries no MDM requirement, no time threshold, and no new-versus-established patient distinction — selection depends on whether a diagnostic evaluation (not psychotherapy) was the purpose of the encounter.

The critical distinction that drives most 90791 compliance issues is the boundary between a diagnostic evaluation and a psychotherapy session. 

OIG’s psychotherapy claims audit found widespread documentation failures across psychiatric codes, and broader coding audits have specifically reviewed 90791 for medical necessity — particularly when billed repeatedly for the same patient or when the note reads more like a therapy session than a diagnostic workup.

What does CPT code 90791 cover?

The essential reference facts for 90791 billing.

Detail	CPT 90791
Description	Psychiatric diagnostic evaluation (no medical services)
Category	Psychiatry — Diagnostic Evaluation
Patient type	N/A (no new/established distinction)
MDM level	N/A (not an E/M code)
Time	No CPT-defined threshold
Common modifiers	95, 93, 90785
Medicare rate	~180.47non-facility/~148.23 facility (2026)
Commonly compared with	CPT 90792

90791 is a diagnostic code — the encounter produces a diagnosis, not a therapeutic outcome. 

The clinician gathers history, performs a mental status exam, reviews collateral information, formulates a differential diagnosis, and creates a treatment plan. 

Psychotherapy techniques may be used during the interview (and can trigger add-on 90785 for interactive complexity), but the primary purpose is evaluation, not treatment.

When should you use CPT 90791?

90791 applies when the primary purpose of the encounter is psychiatric diagnostic evaluation without medical services.

Use CPT 90791 when

• The encounter’s primary purpose is psychiatric assessment and diagnosis — not ongoing therapy
• The clinician performs a clinical interview, mental status examination, and diagnostic formulation
• No medical services (physical exam, medication prescribing, lab ordering) are performed by the evaluating clinician
• The result is a psychiatric diagnosis and treatment recommendation

When not to use it

• Medical services are included (physical exam, prescribing, lab orders) — use 90792
• The encounter is primarily psychotherapy — use 90832/90834/90837
• The clinician performed a general E/M visit with psychiatric focus — use office E/M (99202–99215)
• The evaluation is psychological testing — use 96130–96139
• The session is crisis intervention — use 90839/90840

How is CPT 90791 selected?

90791 has no MDM pathway and no time threshold. Selection depends on the encounter’s purpose — diagnostic evaluation versus treatment.

Evaluation scope

The AMA CPT guidelines describe the psychiatric diagnostic evaluation as including history of present illness, past psychiatric and medical history, social/developmental history, family psychiatric history, mental status examination, review of available data, diagnostic formulation, and treatment planning.

The evaluation may also include communication with family members or other sources and use of standardized assessment instruments. 

When communication complexities materially increase the work (language barriers, maladaptive communication, involvement of third parties), add-on 90785 can be reported alongside 90791.

What 90791 does not include

90791 does not include medical services. 

If the evaluating clinician performs a physical examination, orders lab work, prescribes medication, or reviews/orders diagnostic tests, the encounter is 90792 — the psychiatric diagnostic evaluation with medical services. 

The distinction is binary — any medical service component moves the encounter from 90791 to 90792.

What documentation supports CPT 90791?

The note must demonstrate a genuine diagnostic evaluation — not a psychotherapy session labeled as an evaluation.

Documentation should include

• Treatment plan and recommendations
• Chief complaint and reason for evaluation
• Diagnostic formulation with DSM-5 diagnosis
• Medical history relevant to psychiatric presentation
• Social/developmental history and family psychiatric history
• Review of collateral information and standardized instruments used
• History of present illness (onset, duration, severity, precipitating factors)
• Past psychiatric history (prior diagnoses, treatments, hospitalizations, medications)
• Mental status examination (appearance, behavior, speech, mood, affect, thought process, thought content, perception, cognition, insight, judgment)

A note that reads “Evaluated patient for depression. Will start therapy weekly.” fails because it provides no diagnostic formulation, no MSE, and no clinical reasoning connecting the evaluation to the diagnosis. 

Medicare reviewers specifically look for the MSE and diagnostic formulation as markers distinguishing 90791 from a psychotherapy intake session.

How much does CPT 90791 reimburse?

Payment varies by provider credential — Medicare applies different percentages by practitioner type.

Provider type	2026 non-facility	2026 facility
Physician / Clinical psychologist	~$180.47	~$148.23
NP / PA / CNS (85%)	~$153.40	~$126.00
CSW / MFT / MHC (75%)	~$135.35	~$111.17
Commercial payers (median)	~185–195	Varies

Medicare rates from CMS 2026 PFS national baselines. CSW/MFT/MHC rate reflects 75% of clinical psychologist amount.

Which modifiers apply to CPT 90791?

Modifier 25 does not apply to 90791 — it is not an E/M code. If a same-day E/M is separately warranted, the E/M stands on its own documentation. Here are the modifiers applied:

Modifier	When it applies
95	Synchronous audio-video telehealth
93	Audio-only telehealth (Medicare behavioral health has permanent audio-only eligibility)
90785 (add-on)	Interactive complexity — maladaptive communication, third-party involvement, language barriers, or other factors materially increasing the evaluation’s complexity

CPT 90791 vs. 90792 — which one fits?

The boundary is clean — medical services present or absent.

Feature	CPT 90791	CPT 90792
Service	Psychiatric diagnostic evaluation	Psychiatric diagnostic evaluation with medical services
Medical services	Not included	Included (exam, prescribing, labs)
Typical provider	Psychologist, LCSW, LPC, MFT	Psychiatrist, NP, PA
Medicare rate (2026)	~$180.47	~$230.11
E/M component	None	Included in code

Choose 90791 when the evaluating clinician does not perform medical services — no physical exam, no prescribing, no lab orders.

Choose 90792 when the evaluating clinician also performs medical services as part of the diagnostic encounter. 90792 includes E/M — do not bill a separate office E/M alongside it.

The provider’s credentials do not dictate the code. 

A psychiatrist who evaluates without performing medical services bills 90791. A psychologist who performs 90791 cannot also perform medical services — the scope-of-practice alignment generally self-selects the correct code, but the billing rule follows the service, not the license.

What billing errors should you avoid with CPT 90791?

Here are the billing errors you should avoid with CPT 90791:

1. Billing 90791 when the clinician prescribed medication 

Prescribing is a medical service. Any medication management during the diagnostic encounter means 90792 — not 90791. The error most commonly occurs when psychiatrists or NPs perform the initial evaluation and initiate medications in the same session.

2. Labeling a therapy intake as a diagnostic evaluation 

A first session that primarily gathers history for treatment planning without producing a formal diagnostic formulation is a therapy intake — bill the appropriate psychotherapy code (90832/90834/90837), not 90791.

3. Billing 90791 repeatedly for the same patient 

Medicare’s MUE is 1 unit per day, and most MACs limit 90791 to a small number per patient per year. Repeated diagnostic evaluations for the same patient require documented clinical justification — a new presenting problem, significant clinical change, or re-evaluation after treatment failure.

4. Missing the mental status examination 

The MSE is the core clinical component that distinguishes a psychiatric evaluation from a therapy session. A note without documented MSE findings may not support 90791 on review.

5. Billing a separate E/M alongside 90791 without justification 

90791 encompasses the evaluation work. A same-day office E/M is separately billable only when genuinely distinct clinical work beyond the psychiatric evaluation occurs — and that is rare with 90791.

Frequently asked questions about CPT 90791

Here are some commonly asked questions on this topic: