ABA Billing Codes 97153 & 97155: A 2026 Guide to Units, Concurrent Billing, and Denials

The AMA adopted the current Category I CPT codes for adaptive behavior services in 2019, replacing the temporary Category III (0359T–0374T) codes most payers had used before. Every code in the set except the assessment-administration timing nuance is time-based and billed in 15-minute units, with a single provider type designated per code. Getting the right code attached to the right rendering provider is the foundation of ABA billing — a technician code billed under a QHP, or a QHP code billed under a technician, is the single most common cause of preventable ABA denials.

The QHP-vs-technician split is the spine of this code set. Codes 97153, 97154, and 97152 are rendered by a behavior technician (often an RBT) under the direction of the QHP. Codes 97151, 97155, 97156, 97157, and 97158 are rendered by the physician or QHP themselves — typically a BCBA. Within that split, 97153 is the high-volume direct-therapy code that drives most ABA revenue, and 97155 is the supervisory/treatment-modification code BCBAs bill while overseeing and adjusting the protocol.

CPT 97153 is adaptive behavior treatment by protocol, administered by a technician under the direction of a physician or other qualified health care professional, face-to-face with one patient, each 15 minutes. It is the code that captures the day-to-day one-on-one ABA therapy a behavior technician delivers.

Requirements to bill 97153 cleanly:

• One-on-one, in person. 97153 is a one-patient, face-to-face code. Two patients in the same session is 97154 (group), not two units of 97153.
• Rendered by a technician under QHP direction. The behavior technician (commonly an RBT) delivers the protocol the QHP designed. The QHP does not need to be in the room for every minute of 97153, but the protocol must be authorized and the supervision relationship must be documented.
• Time-based, 15-minute units. Bill one unit per 15 minutes of direct treatment. Apply the 8-minute rule (below) for the final partial unit.
• Prior authorization on file. Nearly every commercial and Medicaid payer requires PA for ABA, with a specific number of authorized 97153 units per authorization period. Billing past the authorized units is the #1 ABA denial.
• Documentation per session. Session notes must show date, start/stop times (or total minutes), the technician's name and credential, the targets worked, data collected, and the link to the authorized treatment plan.

Units math example. A 3-hour (180-minute) one-on-one technician session is 180 ÷ 15 = 12 units of 97153. A 2-hour 50-minute session (170 minutes) is 11 full units (165 minutes) with 5 minutes remaining — under the 8-minute threshold, so it rounds down to 11 units. A 2-hour 53-minute session (173 minutes) clears the 8-minute threshold on the 12th unit and bills 12 units.

CPT 97155 is adaptive behavior treatment with protocol modification, administered by a physician or other qualified health care professional, which may include simultaneous direction of a technician, face-to-face with one patient, each 15 minutes. It is the BCBA-level code for the supervisory, protocol-adjusting work that distinguishes a QHP's time from a technician's time.

What 97155 captures:

• Active protocol modification. The QHP is observing the patient's response to the current protocol and modifying it in real time — changing targets, prompting strategies, reinforcement schedules, or data systems based on the clinical picture.
• Simultaneous direction of a technician (the concurrent-billing path). The CPT descriptor explicitly allows 97155 to include the QHP simultaneously directing a technician. This is the basis for billing 97155 and 97153 concurrently for the same patient (see the concurrent-billing section).
• Rendered by the physician/QHP. 97155 cannot be rendered by a technician. It is QHP time and must be billed under the QHP's NPI as the rendering provider.
• 15-minute units, time-based. Same 8-minute rounding as 97153.

97153 vs 97155 — the distinction payers audit. The difference is whose time it is and what is happening clinically. 97153 is the technician running the established protocol. 97155 is the QHP modifying the protocol. When a BCBA simply observes without modifying anything, that may not support 97155 — payers expect 97155 documentation to show what was modified and why. Billing 97155 for routine technician supervision without documented protocol modification is a frequent audit finding.

Every billable ABA treatment code (97152, 97153, 97154, 97155, 97156, 97157, 97158) and the assessment code 97151 is a time-based, 15-minute-increment code. Getting units right is half of ABA billing accuracy — and the cause of a large share of underpayments and overbilling recoupments.

The 8-minute rule (CMS/AMA mid-point rounding). For a time-based code, you bill a unit once you have provided at least the mid-point — 8 minutes — of that 15-minute increment. The cumulative thresholds:

A session under 8 minutes of a given code is not separately billable. Verify your payer's rounding rule — most commercial and Medicaid payers follow the CMS 8-minute methodology for these codes, but a minority use strict 15-minute blocks (round down only) or their own table, so the threshold for the final unit can differ by contract.

Daily unit caps. Many payers cap total daily or weekly units per code in the authorization (for example, a maximum number of 97153 units per day). Even when a session legitimately ran long, billing above the daily cap triggers a units-exceeded denial. Track the cap as a hard stop in your billing software, not just the period total.

One of the most misunderstood areas of ABA billing is whether 97153 (technician direct treatment) and 97155 (QHP protocol modification) can be billed at the same time for the same patient. The CPT framework allows it — 97155's descriptor explicitly permits the QHP to be simultaneously directing a technician — but payer policy is where the money is won or lost.

How concurrent billing works. When a BCBA is in the room actively directing the technician and modifying the protocol while the technician delivers the one-on-one treatment, the technician's time bills as 97153 and the BCBA's overlapping time bills as 97155. The two codes overlap in clock time but reflect two different rendering providers doing two different things.

The payer-policy reality:

• Some payers allow 97153 + 97155 concurrently with no special modifier, recognizing the CPT intent.
• Some payers require a modifier (often modifier 59 or an HCPCS HO/HN/HM provider-level modifier set, or modifier U-series Medicaid modifiers that vary by state) to identify the distinct providers/services on overlapping timestamps.
• Some payers prohibit billing both on the same time block and will deny one line as a duplicate or overlapping service.
• Many state Medicaid programs publish specific concurrent-billing rules and provider-level modifier requirements for ABA — these vary by state and must be verified against the current provider manual.

Operational guidance: before billing 97153 and 97155 concurrently, confirm the specific payer's policy in writing, document both providers' distinct activities with their own time stamps, and apply whatever provider-level or distinct-service modifier the payer requires. In our ABA denial reviews we typically see concurrent 97153/97155 lines denied not because the service was wrong but because the second line lacked the payer-required modifier or overlapping time stamps were not separately documented. The clinical work was billable; the claim construction was not.

ABA is one of the most authorization-intensive service lines in all of healthcare billing. Nearly every payer requires prior authorization before a single 97153 unit is delivered, and the authorization specifies a finite number of units per code per authorization period (often 6 months). Once those units are gone, every additional claim line denies — usually as units-exceeded or no-authorization — regardless of medical necessity.

The authorization lifecycle that protects ABA revenue:

1. Assessment authorization first. 97151 (and 97152) assessment units are typically authorized separately, before the treatment authorization. Bill the assessment, deliver the treatment plan, then submit the treatment-plan authorization request.
2. Treatment authorization with per-code unit allotments. The treatment auth specifies authorized units for 97153, 97155, 97156, and any group codes — usually for a fixed period. Record the exact per-code unit count and the auth start/end dates.
3. Real-time unit burn-down. The single highest-ROI control in ABA billing is a live unit ledger: authorized units minus billed units minus units-in-progress, per code, per client, per auth period. When a code approaches its cap, the clinical team gets a reauthorization alert before sessions are delivered against units that will deny.
4. Reauthorization lead time. Reauth requests need the updated treatment plan, progress data, and continued-medical-necessity narrative submitted well before the current auth expires. Gaps between authorizations create denied date ranges that are very hard to recover.
5. Match the rendered code to the authorized code. If 97155 supervision hours run higher than authorized while 97153 units remain, you cannot simply shift them — each code is authorized independently. The treatment plan and auth must reflect the actual supervision-to-direct ratio.

The practices that keep ABA accounts receivable clean treat the authorization ledger as a clinical-operations tool, not just a billing afterthought. The technician schedule and the authorized-units ledger have to be the same number.

ABA denials cluster around three root causes: authorization, units, and provider/code mismatch. Here are the named CARC codes you will see on an ABA denial worklist and the fix for each.

Cross-reference: for the bundling logic behind CARC 97 and the modifier-indicator workflow that governs when you can unbundle with modifier 59 or an X-modifier, see our 97 denial code guide and the full CARC denial codes list. For the authorization-absent family (CARC 197/198), the prevention work lives in the prior authorization process.

The two denials that dominate ABA AR — CARC 197 (no auth) and CARC 198 (auth exceeded) — are almost entirely preventable. They are not coding problems; they are workflow problems. A live unit ledger and a reauthorization-lead-time process eliminate the large majority of both.

ABA documentation has to satisfy two audiences at once: the payer's medical-necessity and time-based-billing requirements, and the clinical record. A session note that supports a 97153 or 97155 claim through an audit includes:

• Patient identifiers and date of service.
• Start and stop times (or total minutes) for the billed code — time-based codes require defensible time documentation. A flat 'unit count' without time backing is an audit liability.
• Rendering provider name and credential — RBT/technician for 97152/97153/97154; BCBA/QHP for 97151/97155/97156/97157/97158.
• The authorized treatment plan reference the session worked from, and the specific targets/programs addressed.
• Data collected during the session and the patient's response.
• For 97155 specifically: what was modified and why — the protocol change, the clinical reasoning, and the patient response that drove it. 'Supervision provided' is not enough to support 97155.
• For concurrent 97153/97155: both providers' distinct activities with their own time stamps, plus the payer-required modifier.
• Supervision relationship between the technician and the directing QHP, where the payer requires it.

In our ABA audits we typically see clean clinical notes that nonetheless fail the billing test because start/stop times are missing or the 97155 note does not describe an actual protocol modification. The clinical documentation was fine; the time-based and provider-distinction billing support was not. Building those elements into the session-note template — not adding them at appeal time — is what keeps ABA claims paying on the first pass.