CPT Codes for Mental Health Billing: A Complete Guide for Therapists (2025)

If you bill insurance as a therapist, your CPT codes determine how much you get paid — and whether your claims clear on the first submission. Most solo practices use fewer than a dozen procedure codes, but getting even one consistently wrong costs thousands of dollars annually in underpayments and denials. This guide covers every CPT code used in outpatient mental health billing: what each one means, exactly when to use it, what your documentation needs to say, and the specific mistakes that turn clean claims into problems.

The Intake Code: 90791 — Psychiatric Diagnostic Evaluation

CPT 90791 is used for the comprehensive diagnostic evaluation at the first appointment — reviewing the patient's history, presenting symptoms, prior treatment, functional status, and establishing a working diagnosis and treatment plan. Reimbursement for 90791 is typically 25–40% higher than a standard therapy session, reflecting the additional complexity. Most payers allow one 90791 per patient per year; some limit it to once per provider relationship. Do not use 90791 for follow-up appointments, even if they feel like re-assessment sessions. That is a documentation mismatch auditors look for specifically.

The Three Individual Therapy Codes: 90832, 90834, and 90837

These three codes cover the full range of individual outpatient psychotherapy sessions. They are time-based codes — the actual face-to-face session time, not the scheduled time or the appointment slot, determines which code applies. Billing the wrong code for a documented session time is one of the most common audit triggers in outpatient mental health billing.

90832 — Psychotherapy, 30 Minutes (16–37 Minutes of Actual Session Time)

90832 applies to sessions lasting between 16 and 37 minutes. This is the right code for brief check-ins, follow-ups in collaborative care, or sessions that end early. Medicare reimburses approximately $43–54 for 90832 in Delaware and the mid-Atlantic region. If a session runs 38 minutes, the correct code is 90834 — and the reimbursement difference is material enough to track on every claim.

90834 — Psychotherapy, 45 Minutes (38–52 Minutes of Actual Session Time)

90834 covers sessions lasting 38–52 minutes — the "45-minute hour" in practice. This code is underused because therapists default to 90837 for sessions in this range. If your documentation shows a 48-minute session, 90834 is the correct code. Medicare reimburses approximately $74–88 for 90834; commercial payers often pay 15–30% above Medicare rates. The difference between 90834 and 90837 on a single claim can be $25–50, compounding across a full caseload.

90837 — Psychotherapy, 60 Minutes (53+ Minutes of Actual Session Time)

90837 covers sessions of 53 minutes or longer and is the highest-reimbursing individual therapy code. Medicare reimburses approximately $130–152 for 90837 in Delaware, and most commercial payers reimburse 15–35% above Medicare rates. The 53-minute threshold is exact: a session documented as 52 minutes is a 90834. If you consistently run 55-minute sessions and document them accurately, billing 90837 is correct. If you are billing 90837 for sessions your notes document at 45–50 minutes, you have audit exposure.

Time Documentation: The Detail That Determines Your Code

Because 90832, 90834, and 90837 are distinguished entirely by face-to-face time, your progress note must record start time, end time, and total session duration. "Approximately 60 minutes" does not hold up on audit. "Session began at 2:04 PM and concluded at 3:06 PM — 62 minutes of psychotherapy" does. This single-sentence addition to every note protects you against every time-code challenge. Payers are increasingly cross-referencing documented session times against billed codes when they request records — this is not a theoretical risk.

Crisis Codes: 90839 and 90840

CPT 90839 covers the first 60 minutes of crisis psychotherapy — defined as urgent assessment and intervention for a patient in psychiatric emergency: active suicidal ideation with intent or plan, acute psychotic decompensation, or crisis-level escalation requiring immediate intervention. CPT 90840 is the add-on for each additional 30 minutes beyond the first hour. Reimbursement is substantially higher than standard session codes, but documentation requirements match: the note must establish the clinical basis for crisis-level care, the patient's specific crisis presentation, and the intervention provided. Using 90839 for a difficult session is a compliance violation, not a gray area.

Add-On Codes for Prescribers: 90833, 90836, and 90838

Psychiatrists and prescribing PMHNPs who bill Evaluation and Management codes (99213–99215) can add a therapy component using 90833 (30 minutes), 90836 (45 minutes), or 90838 (60 minutes). These codes bundle psychotherapy with a medication management visit on the same date of service. LCSWs and LPCs cannot bill these codes — they require a base E/M code, which therapists are not licensed to generate.

Group and Family Therapy Codes

Group and family sessions use distinct CPT codes with their own billing rules.

• ▸90853 — Group psychotherapy: one therapist, multiple patients, each patient billed separately. Per-patient reimbursement is lower than individual therapy but per-hour revenue is often comparable. Some payers require prior authorization.
• ▸90847 — Family psychotherapy with patient present: the identified patient participates in the session.
• ▸90846 — Family psychotherapy without patient present: collateral sessions with family members only.
• ▸90849 — Multiple-family group psychotherapy: used in structured outpatient programs; uncommon in solo private practice.

The Coding Mistakes That Trigger Audits

Most billing audits in outpatient mental health practices trace to a short list of documentation mismatches. None require intent to create compliance exposure.

• ▸Time-code mismatch: Note documents 48 minutes; claim billed 90837. The most common audit finding and the easiest to generate on a records request.
• ▸Repeated 90791 use: Billing 90791 more than once per year per patient without documented clinical justification raises flags at most payers.
• ▸Crisis codes without crisis documentation: A note describing a productive session billed under 90839 creates serious compliance exposure.
• ▸Missing session time in notes: Any time-based code without documented start and end time is indefensible on appeal.
• ▸Billing 90837 for scheduled 45-minute slots: Scheduled time and documented time are not the same — payers know this and apply it on audit.

Managing CPT codes, documentation requirements, and payer-specific billing rules alongside a full clinical caseload is a real burden. Logicware handles claim submission, coding review, and denial management for mental health practices in Delaware and across the US. Contact us for a free billing audit to see where your current process has gaps.