CPT Code 90791: Complete Billing and Documentation Guide for Therapists

In the world of mental health care, few billing codes are as essential as CPT Code 90791. This psychiatric diagnostic evaluation code is the foundation for treatment planning, payer reimbursement, and clinical documentation. If you’re a psychologist, counselor, social worker, or family therapist, understanding how to use CPT Code 90791 is essential for keeping your practice compliant and financially healthy.

This in-depth guide breaks down everything therapists need to know about the 90791 CPT code description, proper documentation, billing compliance, recent updates, and how to avoid common errors. 

What Is CPT Code 90791?

CPT Code 90791 is used for a psychiatric diagnostic evaluation that does not include medical services. In simple terms, it refers to a full, face-to-face assessment of a client’s emotional, behavioral, and psychological health.

During this session, the therapist gathers the client’s history, reviews symptoms, checks daily functioning, performs a mental status exam, and creates an initial diagnosis and treatment plan. This code does not include medical services such as prescribing medication or ordering lab tests.

According to AMA/Medicare, CPT 90791 includes

• A complete biopsychosocial assessment

• Review of psychiatric and medical history

• Mental Status Examination (MSE)

• Discussion of diagnosis using DSM-5 or ICD-10

• Initial treatment planning and recommendations

• Evaluation of the client’s ability to engage in treatment

Who Can Bill CPT 90791?

The service code 90791 is specifically designated for licensed mental health professionals without medical prescribing authority, such as:

• Psychologists (PhD, PsyD)

• Licensed Clinical Social Workers (LCSWs)

• Licensed Professional Counselors (LPCs)

• Marriage and Family Therapists (LMFTs)

• Other non-MD/DO behavioral health specialists

Psychiatrists, psychiatric nurse practitioners, or any provider offering medication management should instead bill CPT Code 90792, which includes medical services.

Procedures and Techniques Covered Under CPT 90791

A 90791 session involves a full mental health evaluation that helps the therapist understand a client’s emotional, behavioral, and psychological needs. It typically includes:

• A detailed clinical interview and building rapport with the client

• Reviewing the client’s main concerns and overall life situation (psychosocial context)

• Conducting a Mental Status Examination (MSE) to assess thinking, mood, perception, and behavior

• Reviewing the client’s psychiatric, medical, and family history

• Performing a risk assessment for concerns such as suicide, violence, or substance use

• Evaluating the client’s daily functioning and coping skills

• Creating a preliminary diagnosis using DSM-5 or ICD-10 guidelines

• Developing an initial treatment plan, which may include therapy recommendations, referrals, or further evaluations

How Long Is a 90791 Session?

A 90791 evaluation usually lasts 45 to 90 minutes. While there is no fixed duration, most insurance payers and Medicare expect a comprehensive assessment during this time. The session should reflect the depth and complexity of an initial or full evaluation, not a brief follow-up visit.

What Are the Requirements and Billing Rules for CPT Code 90791?

To bill CPT Code 90791 correctly, therapists must follow certain guidelines set by payers and CPT standards. Here are the key requirements explained in simple terms:

• Face-to-Face Evaluation: The session must be conducted in person or via telehealth using approved telehealth platforms and the correct modifiers.

• When to Use 90791: Use this code for a new client, a comprehensive intake, or when there’s a major change in the client’s condition that requires a full reassessment.

• Who Can Bill 907: The provider must be a licensed mental health professional, such as a psychologist, counselor, social worker, or marriage and family therapist. Not for medical professionals who prescribe medication.

• Documentation Requirements: Every part of the evaluation—history, mental status exam, diagnosis, and treatment plan—must be clearly documented in the client’s record.

• One-Per-Episode Rule: You can typically bill 90791 once per client per episode of care, unless there is a significant clinical change that requires another full evaluation.

• Insurance and Payer Rules: Each insurance plan may have different authorization or frequency limits, so always check your payer’s policy before billing.

• For a deeper look at billing compliance across mental health CPT codes, visit our Complete Provider Guide to Mental Health CPT Codes

Use of Modifiers

• Use modifier 95 or GT for telehealth sessions.

• Add modifier 90785 if the session involves interactive complexity (e.g., interpreter, family dynamics).

When Should You Use CPT Code 90791 vs 90792 for Initial Evaluations?

Both CPT Code 90791 and CPT Code 90792 are used for initial mental health evaluations, but they apply to different types of providers and services. Here’s a simple breakdown:

Code	Who Uses It	What’s Included
90791	Psychologists, LCSWs, LPCs, LMFTs	Diagnostic evaluation without medical management
90792	Psychiatrists, Psychiatric NPs, MDs/DOs	Diagnostic evaluation with medical management

If the session involves prescribing medication, ordering labs, or assessing for pharmacological treatment, use CPT 90792. Otherwise, 90791 is the correct service code.

Which ICD-10 Codes Support CPT Code 90791 for Medical Necessity?

When billing CPT Code 90791, it’s important to include the correct ICD-10 diagnosis code to show the medical necessity of the mental health evaluation. These codes explain why the assessment is needed and help ensure insurance reimbursement.

Here are some of the most common ICD-10 codes used with CPT 90791:

• F32.1 – Major Depressive Disorder, moderate

• F41.1 – Generalized Anxiety Disorder

• F43.23 – Adjustment Disorder with mixed anxiety and depressed mood

• F06.2 – Psychotic Disorder with delusions due to a known physical condition

• F31.1 – Bipolar Disorder, current episode manic

• F43.10 – Post-Traumatic Stress Disorder, unspecified

These ICD-10 codes for 90791 show that the evaluation is clinically necessary for developing an accurate diagnosis and creating an effective treatment plan.

To improve your evaluation code selection, consider this insightful guide on utilizing ICD-10 codes for mental and behavioral health billing success.

Documentation Guidelines for CPT Code 90791

Accurate and detailed documentation for CPT Code 90791 is essential for compliance, reimbursement, and quality care. Your session notes should clearly show the reason for the evaluation, the clinical findings, and the medical necessity for services.

Here’s what to include in your documentation:

• Presenting Problem or Chief Complaint: Write the client’s main concern in their own words.

• Referral Source: Note who referred the client, if applicable.

• Clinical History: Include psychiatric, medical, family, social, and substance use history.

• Current Medications and Allergies: Record all relevant information.

• Mental Status Examination (MSE): Describe findings such as mood, thought process, appearance, and cognition.

• Diagnosis and Clinical Impression: Provide your clinical reasoning and related ICD-10 code(s).

• Initial Treatment Plan: Outline therapy frequency, goals, referrals, and recommendations.

• Session Details: Add the date, time, and duration of the session (actual time, not scheduled).

• Disclosures and Consents: Include acknowledgment of HIPAA and consent forms if discussed.

• Want to improve documentation accuracy and avoid underpayments? Read how EMR improves behavioral health billing accuracy and reimbursement

Sample Note for CPT Code 90791

60-minute, face-to-face diagnostic evaluation (CPT Code 90791) completed with the client and parent. The session included a full Mental Status Examination, along with a review of family background and medical history. The client’s reported symptoms were consistent with Generalized Anxiety Disorder (F41.1). Based on the findings, an initial treatment plan was created, recommending weekly therapy sessions and a school consultation to support ongoing care.

Compliance and Regulatory Guidelines for CPT Code 90791

To stay compliant when billing CPT 90791, follow these key rules:

• The 90791 CPT code must align with AMA CPT Manual and payer-specific policies.

• Do not bill 90791 with other psychiatric E/M or psychotherapy codes for the same session.

• Follow all state and insurance regulations for telehealth, supervision, and provider eligibility.

• Remember the one-per-episode rule: Bill 90791 once per treatment episode unless a new evaluation is medically necessary.

• Keep audit-ready records for at least seven years, and ensure all documentation is securely stored in your EHR system.

These 90791 documentation and compliance guidelines help protect your practice, ensure payment, and demonstrate professional care quality. If you're still unsure whether in-house or outsourced billing is right for your clinic, explore How to Find the Right Billing Service for Your Behavioral Health Practice

FAQ

1. What modifier is used for 90791?

For CPT code 90791, use modifier 95 or GT for telehealth sessions, and 90785 for interactive complexity when communication involves caregivers or special client interaction needs.

2. What is the difference between 90791 and 90792?

CPT 90791 is used for diagnostic evaluations without medical management, while 90792 includes evaluations with medication management or medical testing performed by psychiatrists or prescribing clinicians.

3. Does Medicare pay for CPT 90791?

Yes, Medicare covers CPT code 90791 when provided by licensed mental health professionals. Payment depends on provider credentials, medical necessity, and documentation that supports a comprehensive diagnostic evaluation.

Conclusion

CPT Code 90791 is the foundation for a clear and compliant intake assessment in behavioral health. By understanding its definition, documentation requirements, billing process, common mistakes, and payer rules, therapists can ensure accurate claims and steady reimbursement. Staying updated, being detailed, and following proper guidelines help make every 90791 evaluation a model of quality care and compliance.