CPT code 90791 is the code most mental health clinicians use to bill an initial diagnostic evaluation, often called the intake. This guide explains what CPT 90791 covers, who can bill it, what to document and how it differs from 90837, so your first session with a new client gets paid correctly. Learn more about Sessions Health, a mental health EHR built for talk therapy.
What Is CPT Code 90791?
CPT code 90791 is the code for an initial diagnostic assessment of a client’s mental health, completed without medical services. In practice it covers a clinical interview that gathers history, assesses current symptoms and risk, reaches a diagnosis and informs the treatment plan. Its counterpart, 90792, is used by physicians and other medical practitioners when the evaluation includes medical services. For the official code language, see the AMA’s CPT manual. For comparison, see our guide to CPT code 90834.
Who Can Bill CPT 90791?
Psychologists, clinical social workers, licensed professional counselors, marriage and family therapists and psychiatrists can bill 90791 when it falls within their scope of practice and the payer has credentialed them. Medicare has covered marriage and family therapists and mental health counselors since January 1, 2024. Always confirm each payer’s rules, because eligibility varies by state and plan.
How Long Is a 90791 Session?
CPT 90791 is not a time-based code. It is billed when the required elements of the evaluation are complete, not by the minute, so there is no minimum or maximum time. Most intake evaluations run roughly 45 to 60 minutes. Some payers expect the start and stop times or the total time in your note, so check each payer’s documentation requirements.
What to Document for 90791 Billing
- Reason for referral and presenting concerns
- Psychiatric, medical, substance use and family history
- Mental status examination and risk assessment
- Diagnosis with supporting rationale
- Treatment recommendations and next steps
- Who participated, and start and stop times if the payer requires them
- The interactive complexity factor, when applicable (CPT 90785)
90791 vs 90837: When to Use Each
| Code | Purpose | Typical Use |
| 90791 | Diagnostic evaluation | Intake or a re-evaluation when the clinical picture changes |
| 90837 | 60-minute psychotherapy | Ongoing therapy sessions after the diagnosis is established |
If you are weighing options, read our CPT 90837 guide.
Can You Bill 90791 and 90837 on the Same Day?
CPT guidelines and Medicare’s NCCI edits do not allow 90791 and a psychotherapy code on the same date for the same client. Most commercial payers follow the same rule, so schedule the evaluation and the first therapy session on separate dates.
Billing 90791 by Telehealth
CPT code 90791 can be delivered by telehealth. For Medicare, report place of service (POS) 10 when the client is at home and POS 02 when the client is somewhere else. Use modifier 95 for real-time video and modifier 93 for audio-only. Commercial plans set their own rules, and some require a specific place of service code or the GT modifier for telehealth, so verify each payer’s requirements. Review our guide to modifiers on mental health claims.
How Often Can You Bill 90791?
CPT code 90791 is limited to once per day, and it is usually billed once at the start of care. It can be billed on more than one date for an extended evaluation, or for separate evaluations with informants such as a parent, when medical necessity is documented. Some payers also allow a re-evaluation after a gap in treatment or a significant change in the client’s condition, so check frequency limits in each payer’s policy.
Interactive Complexity: Adding CPT 90785 to 90791
CPT 90785 is an add-on code for interactive complexity. Because it is an add-on, it is reported together with CPT code 90791, never alone. CMS confirms it can be reported with 90791 when specific communication factors complicate the evaluation, such as caregivers with conflicting input or the need for an interpreter. Practitioners often miss this add-on. Document which factor applied and how it complicated the evaluation so the claim is supported.
Common Mistakes When Billing 90791
- Billing 90791 for ongoing therapy sessions
- Missing mental status exam or risk assessment in the note
- Not documenting participants, or the start and stop times a payer requires
- Billing 90791 and a psychotherapy code on the same date for the same client
- Billing 90791 when medical services were provided (that is 90792)
- Missing the interactive complexity add-on (CPT 90785) when it applies
How Sessions Health Helps With Intake and Billing
Send intake forms and consents for e-signature through the client portal before the first session, document the evaluation with a customizable note, then submit the claim electronically from the same record. See our billing software for mental health practices. Full details are on our pricing page.
CPT Code 90791 FAQs
What does CPT 90791 stand for?
It is the billing code for an initial diagnostic assessment, often called an intake, when no medical services are part of the evaluation.
Is 90791 the same as 90837?
No. 90791 is a diagnostic evaluation, while 90837 is a 60-minute psychotherapy session.
Can therapists bill 90791?
Yes, when licensed and credentialed by the payer and the service is within scope of practice. Medicare has covered marriage and family therapists and mental health counselors since January 1, 2024.
What is CPT 90785?
An add-on code for interactive complexity. It can be reported with 90791 when communication factors, such as caregivers with conflicting input, complicate the evaluation.
