How to Use Billing Code 90791 as a Therapist
As a mental or behavioral health therapist, navigating billing codes can feel like a different language. But understanding how to use each code accurately ensures proper reimbursement and compliance with insurance standards. One of the most foundational codes for mental health professionals is 90791.
In this post, we’ll break down what 90791 means, when to use it, and when not to use it. We will also discuss how it compares to other common CPT codes, and best practices to help your practice stay compliant.
What Is CPT Code 90791?
Providers use CPT Code 90791 to bill for an initial psychiatric diagnostic evaluation. This code is reserved for the first session a therapist has with a client, and it covers both assessment and treatment planning. Specifically, 90791 includes:
- A review of the client’s mental health history
- Evaluation of presenting problems
- Exploration of medical and psychiatric history
- A diagnostic formulation
- A recommendation for treatment
Importantly, 90791 does not include medical services, such as prescribing or managing medications. If you’re a psychologist, licensed therapist (LCSW, LPC, LMFT), or non-prescribing clinician, this is your go-to code for an intake session.
🧠 Learn more in the American Psychological Association CPT Code Guidelines.
When Should You Use 90791?
Use 90791 when conducting an initial intake or diagnostic evaluation. Typically, providers bill this code once for each new client. The payer may reimburse it only once per year per provider group for a given patient.
You should use 90791 in situations such as:
- The client is new to your practice
- The client is returning after an extended lapse in care
- You are performing an annual re-evaluation, and the payer allows it
Some payers permit multiple uses of 90791 if a significant clinical change or new diagnosis occurs. However, always verify with the insurance company.
When Not to Use 90791
While 90791 is extremely useful, it’s not a catch-all code. Avoid using it in the following situations:
- For ongoing therapy sessions — use psychotherapy codes like 90832, 90834, or 90837 instead
- If you’re a prescribing provider (e.g., psychiatrist or psychiatric nurse practitioner) conducting an evaluation that includes medication — instead, use 90792
- For group therapy or family sessions — these have separate codes like 90847 (family psychotherapy)
✅ Best practice: Use 90791 only once per client per episode of care, unless explicitly permitted by the insurance provider.
Common Modifiers for 90791
Sometimes, modifiers are needed to clarify the setting or provider type. Here are a few common modifiers you may need to append to 90791:
- Modifier -25: If you’re performing a distinct evaluation service on the same day as another service (rare in therapy, more common in medical settings)
- Modifier -95: For sessions conducted via telehealth using a live interactive audio and video connection
- Modifier -GT: Another telehealth-related modifier, although some payers prefer -95
- Place of Service (POS) codes: These aren’t technically modifiers but are essential in billing — e.g., POS 10 for telehealth from home, or POS 11 for in-office visits
Always check with each payer to determine which modifiers or POS codes they require for 90791 to be reimbursed.
📚 For more on modifiers and telehealth billing, visit the Centers for Medicare & Medicaid Services Telehealth Toolkit.
How 90791 Differs from Other Common Codes (90832, 90834, 90837)
Understanding the distinction between 90791 and psychotherapy codes like 90832–90837 is essential:
| Code | Description | Time Length | Used For | Includes Medical Services? |
|---|---|---|---|---|
| 90791 | Initial psychiatric diagnostic evaluation | Typically 60 minutes | First-time intake or re-evaluation | No |
| 90792 | Diagnostic evaluation with medical services | Typically 60 minutes | Psychiatric intake with medication | Yes |
| 90832 | Individual psychotherapy | 16–37 minutes | Ongoing treatment | No |
| 90834 | Individual psychotherapy | 38–52 minutes | Ongoing treatment | No |
| 90837 | Individual psychotherapy | 53+ minutes | Ongoing treatment | No |
As you will notice, while 90791 is evaluative, the others are interventional — used for providing therapy after the evaluation has been completed.
👀 Curious about psychotherapy CPT codes? Check out this 2025 Mental Health CPT Coding Cheat Sheet from TheraThink.
Best Practices for Using 90791
To ensure you’re using 90791 correctly and maximizing reimbursement, keep these tips in mind:
1. Document Thoroughly
Your intake session notes should reflect all elements of a diagnostic assessment, including:
- Reason for referral or presenting concerns
- Mental status exam
- Clinical observations
- DSM-5 diagnosis or differential
- Treatment recommendations and goals
Quality EHR documentation and clinical notes helps justify the use of 90791 during audits or reviews.
2. Verify Payer Requirements
Some payers have specific policies around 90791:
- Time requirements (typically 60 minutes, but check!)
- Limits on frequency of use
- Requirements for documentation or supervision (especially for pre-licensed clinicians)
🧾 Pro tip: Call the payer’s provider line or check their online provider manual.
3. Avoid Downcoding
Sometimes mental health therapists mistakenly use a 90834 or 90837 for an intake because they’re unsure if 90791 is allowed. This can reduce reimbursement and create inaccuracies in your patient records.
If you’re doing a diagnostic assessment — even if it’s done in under an hour — use 90791 (unless otherwise directed by the payer).
4. Use a Clean Claim
Make sure your claim submission form includes all relevant billing and health information:
- The correct CPT code
- Applicable modifier and POS code
- ICD-10 diagnosis code
- Your NPI and tax ID
- Accurate patient demographics
This reduces rejections and speeds up payment.
Final Thoughts
CPT code 90791 is one of the most vital codes in behavioral health billing. When you use it correctly, you build a strong base for providing a high quality of care. This also helps ensure accurate and compliant billing. Remember that insurance requirements change often, so stay updated on payer rules and industry changes.
If you’re ever in doubt, reach out to your payer rep or consult your mental health EHR system for support. Utilizing an intuitive behavioral health EHR such as CheckpointEHR can help optimize your use of mental health billing codes. Remember: you cannot optimize billing without a high-functioning electronic health record.