How to Bill CPT Code 90791 Correctly: A Complete Provider Guide

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By a Licensed Behavioral Health Provider with Over a Decade of Clinical and Billing Experience

Introduction: Why Getting 90791 Right Matters More Than You Think

When I first started my behavioral health practice, I assumed that as long as I was doing good clinical work, the billing side would take care of itself. I quickly learned that was a costly assumption both financially and professionally. CPT Code 90791 is one of the most commonly billed codes in behavioral health, and it is also one of the most frequently audited and denied.

After years of navigating payer policies, surviving audits, and helping colleagues clean up billing messes that cost their practices thousands of dollars, I want to share everything I know about billing this code correctly. Not just the textbook definition, but the real, in-the-trenches knowledge that protects your practice, supports your patients, and keeps your revenue cycle healthy.

Accurate billing of 90791 is not just a compliance issue it is a patient care issue. When claims are denied or clawed back, providers lose the financial stability needed to keep their doors open and continue serving patients. When documentation is incomplete, continuity of care suffers. Getting this right matters on every level, and I am going to walk you through exactly how to do it.

What Is CPT Code 90791? Definition and Purpose

CPT Code 90791 is defined by the American Medical Association (AMA) as a psychiatric diagnostic evaluation without medical services. This is the code used to bill for an initial, comprehensive psychiatric or behavioral health evaluation performed by a licensed mental health professional such as a licensed clinical social worker (LCSW), licensed professional counselor (LPC), licensed psychologist, or psychiatrist when the evaluation does not include medical services like prescribing or physical examination.

If the evaluation does include medical services, CPT Code 90792 would be used instead. That distinction matters, and I will come back to it when discussing common billing errors.

The purpose of 90791 is to capture the work involved in a complete initial psychiatric assessment gathering the patient's history, understanding their presenting problems, conducting a mental status examination, assessing risk, formulating a diagnosis, and creating an initial treatment plan. This is not a brief screening or a follow-up check-in. This is the foundational evaluation that sets the entire course of treatment.

In my practice, I use 90791 when a new patient presents for their first comprehensive evaluation session. The session typically runs 60 to 90 minutes, and every minute of that time is spent gathering the clinical information I need to understand the whole person sitting across from me. I do not use this code for ongoing therapy sessions, progress notes, or any service that is not an initial diagnostic evaluation. That specificity is essential.

Clinical Components: What Services Justify Billing 90791

This is where many providers run into trouble. There is a significant difference between conducting a thorough psychiatric evaluation and conducting one that meets the documentation and clinical standards required to bill 90791. The code requires a comprehensive, multi-domain assessment. Here is what that means in practice.

Presenting Problem and Chief Complaint. I always start by documenting the patient's own words about why they are seeking help. This is not just good clinical practice it anchors the entire evaluation in the patient's perspective and establishes medical necessity from the first line of the note.

Psychiatric History. I document prior psychiatric diagnoses, previous treatments (including medications, therapy, and hospitalizations), and the outcomes of those treatments. This history informs my clinical decision-making in ways that are directly relevant to the current evaluation.

Medical History and Review of Systems. Even though 90791 is "without medical services," I still document relevant medical history because many medical conditions directly affect psychiatric presentation. Hypothyroidism, traumatic brain injury, chronic pain, and autoimmune conditions can all manifest with psychiatric symptoms. I document what I review, even when findings are negative.

Family History. A thorough family psychiatric and medical history is part of a complete evaluation. I document family history of mood disorders, psychosis, substance use, suicide, and other relevant conditions.

Social History and Developmental History. This includes childhood history, educational background, occupational history, relationship history, trauma history, cultural background, and current living situation. Context is everything in behavioral health, and my documentation reflects that.

Substance Use History. I document current and historical use of alcohol, tobacco, prescription medications, and illicit substances. I note frequency, quantity, and any history of withdrawal or treatment.

Mental Status Examination (MSE). This is non-negotiable. A complete MSE must appear in every 90791 note. I document appearance, behavior, speech, mood (patient's self-report), affect (my clinical observation), thought process, thought content, perceptual disturbances, cognition, insight, and judgment. Abbreviating or skipping sections of the MSE is one of the fastest ways to lose a claim in an audit.

Risk Assessment. I document suicidal ideation (active or passive, with or without plan or intent), homicidal ideation, self-harm history, access to means, and protective factors. I explicitly document my clinical reasoning about level of risk, even when risk is low or absent.

Diagnostic Formulation. I document the DSM-5 diagnosis or diagnoses with supporting clinical rationale. I do not simply list a code I explain why the patient meets criteria, what information supports the diagnosis, and what I considered and ruled out.

Initial Treatment Plan. The evaluation concludes with a treatment plan that includes recommended level of care, treatment modalities, frequency of sessions, goals of treatment, and any referrals made.

A Real-World Example. A 34-year-old woman presented to my office after a referral from her primary care physician. She had been experiencing low mood, fatigue, difficulty concentrating, and social withdrawal for approximately eight months following a job loss and relationship dissolution. My evaluation covered all of the domains above. I documented her complete psychiatric, medical, family, and social history. My MSE revealed a dysthymic affect, psychomotor slowing, and intact but somewhat pessimistic cognition. I conducted a formal risk assessment that revealed passive suicidal ideation without plan, intent, or means, with multiple protective factors including strong family support. My diagnostic formulation supported a primary diagnosis of Major Depressive Disorder, Single Episode, Moderate (F32.1), with a rule-out for Persistent Depressive Disorder given the duration. I created an initial treatment plan recommending weekly cognitive-behavioral therapy and a referral to her PCP for medication evaluation. That note thorough, specific, and clinically grounded is exactly what a properly documented 90791 looks like.

Documentation Requirements: What Your Chart Must Contain

When a payer audits a 90791 claim, they are looking at one thing: does the documentation in the chart support the services billed? If it does not, you will face a denial, a request for refund, or in egregious cases, an allegation of fraud.

Here is what your chart must contain to support a 90791 claim:

Date, Duration, and Provider Credentials. The note must be dated, and it must clearly identify the rendering provider and their licensure. If a supervisee performed the evaluation under supervision, both the supervisee and the supervisor must be identified, and the supervision arrangement must be clearly documented. The time spent is increasingly important as payers scrutinize this.

Chief Complaint in the Patient's Words. This is the clinical foundation of medical necessity. Always include a direct or paraphrased quote from the patient.

Complete History. As detailed above psychiatric, medical, family, social, developmental, and substance use history. The depth of each section should be proportionate to its clinical relevance. A history section that simply says "history unremarkable" will not hold up in an audit.

Complete Mental Status Examination. Every domain. Every time. I use a structured MSE template in my EHR so I never miss a section. Some EHR systems allow you to default common findings (e.g., "Speech: normal rate and rhythm") which is fine but you must review and update those defaults to reflect each individual patient.

Risk Assessment with Clinical Reasoning. Do not just check boxes. Write sentences. "Patient denied SI/HI. Risk assessed as low based on absence of ideation, plan, or intent, stable housing, strong social support, and no recent stressors" is vastly more defensible than "SI: denied."

Diagnosis with Supporting Rationale. List the ICD-10 code and the clinical basis for it. Reference specific findings from your MSE and history that support the diagnosis.

Treatment Plan. Include goals, interventions, frequency, modality, and any referrals. The treatment plan does not need to be elaborate at this stage, but it must be present and it must be individualized. A generic cut-and-paste treatment plan is a red flag in any audit.

Clinical Decision-Making. This is often the most overlooked element. I always include a paragraph that explains my reasoning what I considered, what I ruled out, and why I chose the treatment approach I did. This demonstrates the complexity and medical necessity of the evaluation in a way that no checklist can.

Signature and Credentials. Every note must be signed and credentialed. In many states and for many payers, an unsigned note is essentially a note that does not exist.

Common Billing Mistakes Providers Make With 90791

After years of reviewing charts and consulting with other providers, I have seen the same errors come up again and again. Understanding them is the first step to avoiding them.

Billing 90791 for Follow-Up Visits. This is probably the most common mistake I see. Some providers use 90791 for any "intake" session, even when the patient was seen before at a prior practice or earlier in the year. The code is for an initial diagnostic evaluation one time per episode of care, per provider. Some payers will allow it once per provider, while others limit it more strictly. Know your payer's policy.

Confusing 90791 with 90792. If you are a psychiatrist or other prescriber and you reviewed medications, ordered labs, or performed any medical service during the evaluation, the correct code is 90792, not 90791. Billing 90791 when medical services were provided is undercoding, which creates its own set of problems.

Billing 90791 for Supervisees Without Proper Documentation. When a student intern or pre-licensed clinician conducts the evaluation under supervision, both providers must be appropriately documented. Simply having the supervisor co-sign without reviewing the note and documenting their involvement is not sufficient for most payers.

Incomplete MSE. A mental status exam with only two or three domains documented will not support the billing level. I always use a structured format so completeness is built into my workflow.

Vague or Generic Documentation. "Patient presents with depression and anxiety. Assessment and plan as above." That is not a psychiatric evaluation that is a billing risk. Every section of the note should be specific to the individual patient.

Failing to Document Time. Some payers require the time of the evaluation to be documented. Even when not explicitly required, documenting time strengthens your claim and provides context for the thoroughness of the evaluation.

Using 90791 the Same Day as Other Services. Most payers will not reimburse 90791 on the same date of service as psychotherapy codes (90832, 90834, 90837) or certain testing codes. Check your payer's bundling rules before combining services on the same date.

Audit Defense and Compliance: How I Protect My Practice

Audits are not something I fear they are something I prepare for. The best audit defense is a clean, thorough, contemporaneous note. Here are the practices I follow to make sure I am always audit-ready.

Document in Real Time. I write my notes during or immediately after the evaluation. Notes written days later are harder to defend and raise questions about accuracy. If I need to add information later, I make an addendum clearly dated and timed, not an alteration of the original note.

Use a Structured Template for 90791. My EHR template for 90791 prompts me to complete every required element before I can close the note. This is not about being robotic it is about making sure nothing falls through the cracks when I am seeing a full schedule of patients.

Conduct Internal Chart Reviews. Every quarter, I pull a random sample of my own 90791 claims and review them against a documentation checklist. If I find a pattern of missing elements, I correct it immediately. Finding your own issues before a payer does is far better than the alternative.

Stay Current on Payer Bulletins. CMS, Medicaid, and commercial payers update their policies regularly. I have alerts set up for my major payers so I receive notices of policy changes. When a new bulletin comes out, I read it and update my practices accordingly.

Keep Credentials and Enrollment Current. A common audit trigger is a billing discrepancy between the rendering provider's NPI and the credentialing information on file with the payer. I review my CAQH profile and payer enrollments annually to make sure everything is current and accurate.

Train My Billing Staff. If you use a billing service or have internal billing staff, they need to understand the clinical requirements of 90791 just as much as the billing mechanics. A billing team that catches documentation gaps before submission is worth its weight in gold.

Payer Variations: Medicare, Medicaid, and Commercial Insurers

One of the frustrating realities of billing 90791 is that the rules are not uniform across payers. Here is what I have learned about navigating the major payer categories.

Medicare. Medicare covers 90791 under the Mental Health Treatment Limitation rules. Medicare requires that services be medically necessary and that documentation supports the diagnosis. Medicare also has specific rules about provider types not all licensed mental health professionals can bill Medicare independently, so verify your enrollment status carefully. Medicare does not typically have a session frequency limit for 90791, but it does require that the evaluation be the initial diagnostic assessment, not a repeat service.

Medicaid. Medicaid rules vary significantly by state. In some states, Medicaid managed care organizations (MCOs) have additional requirements beyond standard documentation including prior authorization for certain populations or settings. Some state Medicaid programs require that 90791 be completed within a specific timeframe of enrollment in services. I always check the state-specific Medicaid provider manual and any MCO-specific policies for my region.

Commercial Insurers. Commercial plans can be the most variable of all. Some follow CPT guidelines strictly, while others have carved out behavioral health benefits to a separate managed behavioral health organization (MBHO) with its own policies. Always verify benefits and any specific documentation requirements before the evaluation. Some commercial payers require a prior authorization for 90791 in certain circumstances, while others do not. Assuming your approach from one commercial payer applies to another is a reliable way to generate denials.

My Advice on Payer-Specific Policies. Call the provider relations line for each of your major payers and ask specifically about their 90791 requirements. Ask about time limits, documentation expectations, supervisor billing requirements, and any prior authorization rules. Document what you are told, including the date of the call, the name of the representative, and the reference number. That documentation has saved me more than once when a claim was incorrectly denied.

Tips and Best Practices: How I Nail 90791 Billing Every Time

After everything I have shared, here is my practical, actionable guide to billing 90791 with confidence.

Before the Evaluation

Verify the patient's insurance and confirm that 90791 is a covered benefit under their plan. Check for prior authorization requirements. Confirm that the patient has not already had a 90791 billed with another provider in your group during the same episode of care, if your payer restricts this.

During the Evaluation

Conduct a comprehensive assessment covering all required clinical domains. Do not rush. The thoroughness of the evaluation is both a clinical and billing necessity. Take notes as you go so you capture detail in real time.

Documentation Checklist (Use This Every Time)

• Chief complaint documented in patient's own words

• Complete psychiatric history

• Complete medical history and review of systems

• Complete family history

• Complete social and developmental history

• Substance use history

• Full Mental Status Examination (all domains)

• Formal risk assessment with clinical reasoning

• Diagnosis with ICD-10 code and supporting rationale

• Initial treatment plan (individualized, specific, with goals)

• Clinical decision-making and reasoning paragraph

• Time documented

• Provider signature with credentials

• Supervisory documentation if applicable

After the Evaluation

Submit your note within 24 hours of the session. Review the claim before submission to confirm the diagnosis code matches the documentation, the rendering provider NPI is correct, and no unbundling violations exist.

Track Your Denials. Every denial of a 90791 claim is a teaching moment. When I receive a denial, I review the reason code, pull the note, and determine whether it was a documentation issue, an eligibility issue, or a payer policy issue. I track denial reasons by payer in a simple spreadsheet. Over time, patterns emerge and I can address them proactively.

Build Relationships with Payer Contacts. I maintain contact information for provider relations representatives at each of my major payers. When I have a question about a policy or need to appeal a denial, having a name and direct number speeds the process considerably.

Invest in Continuing Education. Billing regulations change. I attend at least one behavioral health billing webinar or workshop per year, and I stay connected with professional associations that provide billing guidance updates for my licensure type.

Conclusion: Bill 90791 With Confidence

Billing CPT Code 90791 correctly is not complicated once you understand what is required. It demands a thorough clinical evaluation, comprehensive and specific documentation, and a working knowledge of payer policies. When all three of those elements are in place, you have a defensible claim that supports your patients, sustains your practice, and holds up under scrutiny.

The providers I have seen struggle most with 90791 billing are usually struggling with one of two issues: they are rushing through documentation because of time pressure, or they are not staying current on payer requirements. Both are fixable. Invest in a good documentation template, build time for thorough note-writing into your schedule, and commit to reviewing your payer policies at least once a year.

I want to encourage you to take what I have shared here and implement it in your own practice not all at once, but methodically. Start with your documentation template. Conduct a review of your last ten 90791 notes against the checklist in this guide. See where the gaps are and address them. The investment of time up front will pay dividends in reduced denials, stronger audit defense, and the confidence that comes from knowing you are doing this right.

You became a behavioral health provider to help people. Billing correctly is part of honoring that commitment it keeps your practice sustainable so you can keep showing up for the patients who need you. You have the knowledge. Now use it.

Disclaimer: This blog post is intended for educational purposes and reflects one provider's clinical and billing experience. It does not constitute legal, billing, or compliance advice. Always consult with a certified medical billing professional or healthcare attorney for guidance specific to your practice and jurisdiction.

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