90791 and 90837 are the pillars of psychiatry medical billing. 90791 is for Psychiatric Diagnostic Evaluation, and 90837 is for 60-minute Psychotherapy. This guide will specify each code, clarify its use cases, outline best documentation practices, discuss the specifics of reimbursement (including Medicare and insurance regulations), address billing pitfalls, and provide a table with the codes listed side by side for easy reference.
CPT 90791 is a code for an initial psychiatric diagnostic evaluation, which does not include medical services. Practically, this is the first evaluation with a new patient. It consists of the process of collecting extensive information to conduct a diagnosis and develop a treatment plan. Notably, therapy interventions or medical management (i.e., no prescription of medication) are not mentioned in the 90791 CPT code during that session.
90791 Cpt Code Time: CPT code 90791 does not have a time requirement; it is not time-related, such as the case of psychotherapy. Most clinicians typically spend 45-60 minutes on each session. However, they may be extended in case of complex situations. The fact is that the evaluation is comprehensive and includes the patient’s history, symptoms, and mental status.
Purpose: CPT code 90791 is assigned when a psychiatric diagnostic evaluation (no medical services) is carried out (generally when an initial intake session is performed). It entails taking a detailed history, including psychosocial, medical, and family history, and a mental health examination. The purpose is to evaluate the mental health of a patient, diagnose him or her, and build a preliminary treatment plan or refer him or her.
Who Can Bill 90791: The code 90791 CPT can be applied by every licensed mental health clinician who is qualified to diagnose and treat any mental condition. This includes psychiatrists, psychologists, licensed social workers (LCSWs), licensed professional counselors (LPCs), psychiatric nurse practitioners and others who are licensed by their state and can be accepted by payers.
Frequency: Generally, 90791 is billed only once per patient, per provider, per episode of care. Insurers (including Medicare and commercial plans) typically pay for one initial evaluation at the start of treatment. Some payers allow one 90791 per year per patient as a general rule, unless special circumstances require another.
Definition: CPT 90837 is the code for the individual patient psychotherapy session, which lasts about 53 minutes. As long as at least 53 minutes of in-person (or telemedicine) psychotherapy are spent, it is a typical treatment session lasting an hour. CPT code 90837, as opposed to 90791 evaluation, relates to treatment, specifically talk therapy using any methodology (such as cognitive behavioral therapy or psychodynamic therapy) that is customized for the patient. Although 90837 is used when the session is 53 minutes or more, codes of similar treatment are also accessible in shorter sessions (90834, which lasts roughly 45 minutes, and 90832, which lasts roughly 30 minutes).
Duration: The shortest time billed for the 90837 CPT code is 53 minutes of face-to-face psychotherapy time. The sessions that are less than such are to be charged using a shorter-duration code (e.g., 90834 38-52 minutes). No extra maximum session length regarding 90837, though practically it is an area of therapy of about 53 minutes.
Purpose: Enter 90837 in case of continuing individual therapy sessions where the psychotherapy needs one hour. This code would be suitable when doing comprehensive counseling or therapy to overcome the mental health conditions of the patient in a session that is long enough to explore the delicate or sensitive aspects of the patient. The 90837 scenarios consist of those sessions with the detailed processing of trauma, crisis intervention, multiple or severe problems that require long-term work, or any visit related to the therapy where a 45-minute session will not be enough.
Who Can bill 90837: 90837 can be billed like 90791 by licensed psychotherapists of different disciplines. The 90837 can be used by psychologists, therapists (LCSW, LPC, LMFT, etc.), psychiatrists, and psychiatric NP (when providing an honorary), and any other licensed mental health clinician, provided that they deliver a psychotherapy service. Unless the provider is only addressing the medication or other medical problems, suppose they are also dealing with them during the visit. Then, they can charge an E/M visit with an add-on code of psychotherapy, instead (a psychiatrist would have to do a med check plus therapy, billing as E/M + 90838 add-on, not E/M 90837 alone).
Frequency: There is no set limit to how often 90837 can be billed, as it will depend on the patient’s treatment plan and medical necessity. In outpatient practice, 90837 may be used for weekly sessions or as frequently as intensive therapy is provided. Medicare and many insurers cover psychotherapy sessions as needed, but excessive frequency (daily long sessions, or multiple 90837s per week long-term) could be scrutinized.
| Aspect | CPT 90791 — Psychiatric Diagnostic Eval | CPT 90837 — 60-min Psychotherapy |
|---|---|---|
| Description & Purpose | Initial psychiatric diagnostic evaluation — used for intake assessments, forming treatment plans. | Individual psychotherapy focusing on treatment interventions. |
| Typical Duration | Not time-based; requires at least 53 minutes or face-to-face evaluation. | Requires at least 53 minutes of face-to-face therapy. |
| Who Can Bill | Licensed mental health professionals, therapists, psychologists, psychiatrists. | Therapists only. |
| Includes Medical Services? | Comprehensive intake note — usually once per episode. | Detailed therapy progress note. |
| Key Documentation | Used for an episode. | No strict limit if medically necessary. |
| Appropriate Use | Usually once per episode. | No strict limit if medically necessary. |
| Frequency Limitations | Billing for an established patient’s assessment. | Billing 90937 for a short session. |
| Common Mistakes |
- Billing for an established patient’s visit (not allowed — use therapy code instead). - Using 90791 multiple times without meeting criteria (likely denied). - Including medication management but not using 90702 (coding error). |
- Billing 90637 for a short session among others for CTX1 (id-allowed). - Billing 90937 for a short session (not allowed). |
This code is used at the start of care or a new episode. Appropriate scenarios include:
This code is used for individual therapy sessions lasting 53+ minutes. Scenarios where 90837 is appropriate include:
Accurate and thorough documentation is essential to support both 90791 and 90837. Each code has specific documentation needs:
For 90791, write a cohesive intake that shows medical necessity and establishes a new episode of care. Start with the presenting problem in the patient’s words, then briefly capture HPI, psychosocial context (supports, risks, substance use, trauma), and relevant medical/psychiatric history and prior treatment response. Document a structured MSE (appearance/behavior, speech, mood/affect, thought process/content, perception, cognition, insight/judgment) and link notable findings to the complaint.
Provide diagnostic impressions or provisional diagnoses with key differentials and what data you still need. Outline a clear initial plan (modality, goals, frequency, safety steps, referrals/med eval as required). Note the duration or start–stop times, indicate whether the visit is in-person or telehealth, include the payer-required modifier (e.g., 95/GT), and explicitly state that this is the initial diagnostic evaluation for this episode.
For 90837, document the exact start and end times to substantiate a ≥53-minute psychotherapy session, noting any brief pauses if clinically relevant. Describe the specific interventions used (e.g., CBT restructuring, exposure work, trauma processing, skills coaching) and the problems or goals addressed so it’s clear what therapy was delivered.
Record the patient’s response level of engagement, insights, behavioral practice, barriers, and link this to observed changes in symptoms or functioning. Include an assessment of progress or status, citing any rating scales or risk updates completed during the visit. Close with a clear plan, including the next session’s cadence, targeted focus, assigned homework, and any coordination with prescribers or external supports, demonstrating how the session advances the ongoing treatment plan.
Both CPT codes 90791 and 90837 can be provided via telehealth if permitted by the payer. When documenting telehealth sessions, note the platform/method used, that it was synchronous video (or audio if audio-only allowed by policy), and the patient’s consent to telehealth. Add the telehealth modifier (95 or GT) to the CPT code on the claim per payer guidelines. Many insurers, including Medicare, have parity for telehealth, so these codes are reimbursed similarly to in-person, provided you document properly.
Rebates on both 90791 and 90837 are relatively high relative to other shorter or less intensive services, yet 90791 is generally rated a little higher since it is comprehensive. To use the example, the Medicare fee schedule of 2025 covers approximately $166.91 CPT 90791 (Psychiatric Diagnostic Evaluation) and $154.29 CPT 90837 (60-minute psychotherapy).
This indicates that at the beginning, an initial assessment is more resource-based (diagnosis and planning) compared to a regular therapy session. The payment of the private insurance will depend, however, 90837 will be more expensive than 90834 (45-minute therapy) and less expensive than 90791 per session. Providers need to know that the contracted rates vary depending on the insurer and area; it would be prudent to be aware of your fee schedule to estimate the revenue.
Even seasoned clinicians can run into billing issues with 90791 and 90837. Here are some common mistakes and how to avoid them:
Choosing between 90791 and 90837 comes down to intent and time: use 90791 to open a new episode with a comprehensive diagnostic evaluation (no medical services), and use 90837 for ≥53 minutes of substantive psychotherapy. Pair each code with the right note, a thorough intake for 90791, and a detailed therapy note with start–stop times for 90837 to demonstrate medical necessity and withstand payer review. Build a simple routine: verify coverage, follow payer rules on frequency and telehealth, select the correct alternative when applicable (90792 for med management; 90834 for 38–52 minutes; E/M + 90838 when prescribing), and self-audit for patterns that trigger scrutiny. When your coding, documentation, and policies align, denials drop, reimbursement is faster, and the record accurately reflects the care delivered, protecting both your patients and your practice. Clinics offering mental health billing services or psychiatry billing services should build standardized templates, train teams, and self-audit billing patterns to ensure compliant, accurate claims.
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