Billing GUide

Behavioral Health Coding Guide

Understanding the right codes to use—and how to bill them correctly—is critical to maximizing reimbursement and minimizing denials in behavioral health revenue cycle management.

How Behavioral Health Billing Codes Work

Medical billing relies on standardized code sets to communicate what services were rendered, who provided them, and under what circumstances. For behavioral health and addiction treatment, three main code types are used depending on the setting and claim form.

CPT Codes

Current Procedural Terminology codes describe outpatient services like psychotherapy, diagnostic evaluations, and psychiatric medication management.

Used on: CMS-1500 professional claims for individual providers and outpatient clinics.

HCPCS Codes

Healthcare Common Procedure Coding System codes cover services not included in CPT, including intensive outpatient programs (IOP), partial hospitalization (PHP), and residential treatment.

Used on: CMS-1500 or UB-04 claims depending on facility type and payer requirements.

Revenue Codes

Used exclusively on institutional claims (UB-04) to classify the type of accommodation or ancillary service provided in facilities like detox centers, residential treatment, or hospital-based programs.

Used on: UB-04 institutional claims only, often paired with HCPCS codes.

Note: Matching the correct code to the level of service, documenting medical necessity in clinical notes, using appropriate modifiers, and ensuring time thresholds are met. Even one missing element can trigger a denial or delay payment by weeks.

CPT Codes

Psychiatric & Therapy Billing Codes

These CPT codes are used for outpatient mental health services including diagnostic evaluations, individual therapy, and family therapy sessions. They require precise time documentation and appropriate provider credentials.

90791

Psychiatric Diagnostic Evaluation

An initial diagnostic interview exam that does not include medical services (no prescribing or monitoring of medication).

Billed too frequently – most payers allow once per 6-12 months per provider

90792

Psychiatric Diagnostic Evaluation with Medical Services

Initial diagnostic interview including medical services (prescription of medications, physical exam elements).

Must be billed by medical provider – Master’s level clinicians cannot use this code

90834

Psychotherapy, 45 Minutes

Individual psychotherapy provided to the patient and/or family member.

Missing start and stop times in clinical notes

90837

Psychotherapy, 60 Minutes

Extended individual psychotherapy session

Routine use flagged – should be exception requiring medical necessity proof

90847

Family Psychotherapy

Psychotherapy involving patient’s family members with primary patient present.

Missing modifier when billed same day as individual psychotherapy

90791

Psychiatric Diagnostic Evaluation

An initial diagnostic interview exam that does not include medical services (no prescribing or monitoring of medication).

Billed too frequently – most payers allow once per 6-12 months per provider

90792

Psychiatric Diagnostic Evaluation with Medical Services

Initial diagnostic interview including medical services (prescription of medications, physical exam elements).

Must be billed by medical provider – Master’s level clinicians cannot use this code

CPT Codes

Addiction Treatment Billings Codes

HCPCS codes are essential for billing higher levels of care including intensive outpatient programs (IOP), partial hospitalization (PHP), residential treatment, and specialized behavioral health counseling. These codes often require pre-authorization and strict adherence to minimum time or service requirements.

H0001

Alcohol/Drug Assessment

Comprehensive alcohol and/or drug assessment to determine the level of care needed.

Billed too frequently—most payers only allow once per admission, episode, or per 6-12 months.

H0004

Behavioral Health Counseling

Behavioral health counseling and therapy.

Unit limits exceeded (hitting strict daily or weekly caps).

H0005

Alcohol/Drug Group Counseling

Alcohol and/or drug services; group counseling by a clinician.

Missing group attendance documentation or exceeding maximum allowed group size limits.

H0012

Sub-Acute Detoxification

Alcohol and/or drug services; sub-acute detoxification (residential addiction program outpatient).

Exceeds approved length of stay or lacks medical necessity documentation for sub-acute care.

H0013

Acute Detoxification

Alcohol and/or drug services; acute detoxification (residential addiction program outpatient). Requires moderate to high medical decision-making.

Billed hourly instead of per diem, or clinical notes do not prove medical necessity for an acute level of care.

H0014

Ambulatory Detoxification

Alcohol and/or drug services; ambulatory (outpatient) detoxification where the patient returns home daily.

Patient stability is not documented—must explicitly show medical appropriateness for completing detox in an outpatient setting.

H0015

Intensive Outpatient Program (IOP)

Alcohol/drug services intensive outpatient (treatment program that operates at least 3 hours/day and at least 3 days/week).

Lack of prior authorization or clinical notes fail to document the strict 3-hour minimum daily participation.

H0018

Short-Term Residential Treatment

Behavioral health; short-term residential (without room and board). Typically less than 30 days.

Insufficient documentation of why a lower level of care (like IOP or PHP) is unsafe or inappropriate.

H0019

Long-Term Residential Treatment

Behavioral health; long-term residential (without room and board). Typically more than 30 days.

Failure to demonstrate continued progress in treatment plans to justify the extended length of stay.

H2036

Behavioral Health Room and Board

Per diem, room and board, therapeutic behavioral services, according to room and board guidelines.

Lacks proof of medical necessity showing the patient requires 24-hour structured care and supervision.

H0020

Methadone Administration

Alcohol and/or drug services; methadone administration and/or service (provision of the drug by a licensed program).

Billed by an unauthorized facility or billed for general residential care instead of specific methadone administration.

HOw IT Works

Essential Modifiers for Behavioral Health

Modifiers are two-character codes appended to CPT or HCPCS codes to provide additional context about how a service was performed. They communicate critical details like provider credentials, whether services were delivered via telehealth, or if multiple distinct procedures occurred on the same day. Incorrect or missing modifiers are a leading cause of claim denials in behavioral health billing.

-25

Separate E/M service same day (e.g., med-check + therapy)

-59

Distinct procedural service - independent from other same-day services

-HO

Master's degree level clinician

-HN

Bachelor's degree level clinician

-95 or -GT

Synchronous telemedicine (audio and video)

When to Apply Modifiers

Credential Modifiers (-HO, -HN): Required when the rendering provider is not a licensed physician or psychologist. Master's-level therapists use -HO, Bachelor's-level counselors use -HN.
Telehealth Modifiers (-95, -GT): Must be appended when services are delivered remotely via audio-video technology. Failure to include these can result in reduced reimbursement or outright denial.
Same-Day Modifiers (-25, -59): Use when billing multiple services on the same date. -25 indicates a separately identifiable evaluation and management service, while -59 signals that procedures are distinct and not bundled.