Understanding ABA Therapy CPT Codes

Last Updated on September 12, 2025 by admin

For ABA therapy providers, billing isn’t just paperwork, it’s a reflection of your services, your standards, and your ability to run a sustainable practice. Every time you submit a claim using ABA Therapy CPT codes, you’re telling a payer: This is what we did, and this is why it matters.

But here’s the truth: even seasoned BCBAs and experienced billers make mistakes. Not due to lack of effort, but because ABA billing is nuanced, and governed by strict compliance rules. A misunderstood modifier or misapplied code can lead to denials, payment delays, or worse, a payer audit.

According to CodeEMR About 20% (1 in 5) of medical claims are denied on the first submission, and nearly 80% of these denials are preventable and linked to coding errors and documentation issues.

This guide walks you through the five most common CPT code mistakes in ABA therapy and shows you how to avoid them with clarity and confidence.

Important ABA Therapy CPT Codes to know

In the context of ABA therapy, Current Procedural Terminology (CPT) codes serve as standardized descriptors for the type and complexity of services delivered. Insurance carriers rely heavily on these codes to determine whether a claim is reimbursable.

Here are the most commonly used ABA billing codes:

• 97151 – Behavior identification assessment
• 97153 – Adaptive behavior treatment by protocol (typically delivered by RBTs)
• 97155 – Adaptive behavior treatment with protocol modification (delivered by BCBAs)
• 97156 – Family adaptive behavior treatment guidance
• 97157 – Multiple-family group adaptive behavior treatment guidance
• 0362T & 0373T – Category III codes for complex assessments or services involving multiple technicians and BCBA oversight

Each of these codes corresponds not just to a session type, but to specific rules, around who can provide the service, how it’s delivered, and how long it must last.

Mistake #1: Misusing 97151 for Non-Assessment Services

What it is: CPT Code 97151 is used for behavioral assessments conducted by a BCBA or licensed clinician. This includes direct observation, caregiver interviews, and the development of a treatment plan.

Where it goes wrong: We often see clinics billing 97151 when the session is simply data collection by a technician or informal observation without clinical assessment.

The fix: Always document the BCBA’s direct involvement, the specific assessment tools used (e.g., VB-MAPP, ABLLS-R), and how results contributed to clinical decision-making. Without this, the claim could be denied or flagged.

Mistake #2: Treating 97153 as a Catch-All Code

What it is: 97153 covers direct 1:1 adaptive behavior treatment delivered by a technician under a BCBA’s supervision.

Where it goes wrong: Many practices use 97153 for every direct session, even when the session involves protocol adjustments or the BCBA is actively modifying the treatment plan.

The fix: If the BCBA is involved and making real-time clinical decisions, you should be billing 97155 instead. Mislabeling these sessions not only undercuts your reimbursement but also fails to reflect the value of your professional expertise.

Mistake #3: Underdocumenting 97155

What it is: CPT Code 97155 reflects sessions where the BCBA is working directly with the client and making protocol changes based on real-time data.

Where it goes wrong: While many providers correctly use 97155, they fail to fully document the intervention changes, rationale, or how the session diverged from the original protocol.

The fix: Your documentation must detail the clinical decision-making: what changed, why it changed, and how the client responded. Payers expect this level of specificity to justify the higher-value service.

Mistake #4: Using 97156 for Parent Updates

What it is: This code is designed for family guidance and caregiver training, not for casual updates or standard progress summaries.

Where it goes wrong: Billing 97156 during sessions where the client is present, or when the BCBA simply explains session data to a parent.

The fix: Use this code only when the family is being trained in behavior intervention techniques. Document learning objectives, strategies discussed, and any role-playing or feedback given. If it’s just an update, don’t bill 97156.

Mistake #5: Rounding Up on Time-Based Codes

What it is: Many applied behavior analysis CPT codes, including 97153 and 97155, are time-based, billed in 15-minute units.

Where it goes wrong: A session that lasts 23 minutes being billed as two units, or time rounding across multiple sessions.

The fix: Track time precisely. Each 15-minute unit must be fully met. 23 minutes equals one unit, not two. Most payers do not allow rounding up, and inconsistent time reporting is a common trigger for audits.

Don’t Forget About Category III Codes

When managing billing for ABA therapy, it’s easy to focus on the standard CPT codes used for assessments and treatment. However, Category III codes are often underutilized, even though they’re designed for some of the most demanding clinical scenarios. 

These codes apply to high-acuity cases that require more staff, intensive support, or on-the-fly protocol adjustments. Used correctly, they ensure providers are appropriately reimbursed for the additional resources involved.

• 0362T – Behavior ID assessment requiring multiple staff and equipment (complex cases)
• 0373T – Treatment with protocol modification for severe behaviors requiring 2+ techs and a BCBA

These codes reflect the true complexity and intensity of certain ABA services. If your team is handling high-risk cases but only billing 97151 or 97153, it’s time to reassess. Review your documentation and coding strategy. Make sure your clinical and billing teams understand when and how to use Category III codes. This leads to more accurate claims, and proper recognition for the work being done, both clinically and financially.

Best Practices to Keep Your Coding Compliant

Compliance isn’t just about avoiding denials or audits. It’s about making sure your services are seen, valued, and reimbursed appropriately. Payers are looking more closely than ever, that’s why billing teams and clinicians must work together. Every session should be backed by clear, accurate, and defensible documentation.

To protect your revenue and compliance status:

• Audit your CPT code usage monthly
• Train BCBAs and techs on documentation expectations
• Align session notes with the selected codes
• Track exact service times
• Stay current on payer-specific coding updates

You’re doing complex, meaningful work. But unless it’s accurately reflected in your coding, it may not be fully reimbursed, or worse, may get flagged by payers.

At AnnexMed, we specialize in ABA therapy billing services. Our certified team understands ABA Therapy CPT codes, modifier usage, and insurance documentation inside and out. We help ABA providers across the U.S. eliminate guesswork, reduce denials, and maximize collections.

Let’s help you code confidently, so you can focus on what truly matters: your clients.