ABA Billing 97153 & 97155 Concurrent Denials: Fix Them Now

The pattern we’re seeing across roughly 50 behavioral health and ABA practices in our RCM portfolio is remarkably consistent: practices billing CPT 97153 and 97155 on the same date of service are getting hit with concurrent-service denials at rates between 18% and 34% of submitted claims, depending on the payer. For a mid-sized ABA practice billing 400 to 600 units per week, that translates to $8,000 to $22,000 in monthly held or lost revenue. Most practices assume it’s a documentation problem. In the majority of cases we review, it is actually a modifier, POS, and claim-stacking problem that is entirely recoverable.

We want to walk through exactly what is triggering these denials in 2026, which payers are the most aggressive, and the specific corrective steps we use to get concurrent-service claims paid on first submission or successfully appealed within 30 to 45 days. This is not a theoretical overview. It is what we are actively doing in the billing queues of ABA providers right now.

What 97153 and 97155 Actually Represent and Why Payers Flag Them Together

CPT 97153 is Adaptive Behavior Treatment by Protocol, meaning direct one-on-one therapy delivered by a technician (RBT or paraprofessional) under a BCBA’s supervision. CPT 97155 is Adaptive Behavior Treatment with Protocol Modification, delivered by or with direct involvement of the BCBA themselves. Both are reported per 15-minute unit.

When a BCBA is actively supervising an RBT delivering 97153 while simultaneously conducting protocol modification (97155), payers interpret this as two providers billing for the same patient at the same time without adequate differentiation. Many commercial payers, including several Medicaid managed care organizations in Florida, Texas, and Pennsylvania, have automated edits that flag same-day 97153 and 97155 claims as potentially duplicative or unbundled. The denial reason codes you will most commonly see are CO-97 (benefit for this service is included in allowance for another service or procedure), CO-4 (the procedure code is inconsistent with the modifier), and B15 (this service/procedure requires that a qualifying service/procedure be received and covered).

The Modifier Stack That Is Getting Claims Denied in 2026

The single most common billing error we audit is the absence of the correct modifier combination on the 97155 line when it is billed concurrently with 97153. Here is the modifier logic that governs these claims in 2026:

• 97155 with Modifier HO: Required by most Medicaid plans to indicate the service is being rendered by a master’s-level or doctoral-level provider (BCBA). Without HO, many Medicaid MCOs auto-deny.
• 97155 with Modifier 95 or GT: Required when the BCBA supervision component is conducted via telehealth. Mixing in-person 97153 with telehealth 97155 without the correct modifier is a frequent audit trigger.
• 97153 with Modifier HN or HA: Several state Medicaid programs require HN (bachelor’s-level provider) or HA (child/adolescent) on the 97153 line to distinguish the technician’s service from the supervisor’s service. Omitting these creates a “same provider” flag even when the rendering NPI differs.
• Modifier 59 or XP on one line: When concurrent services are medically necessary and clinically distinct, Modifier 59 (distinct procedural service) or the more specific XP (separate practitioner) is required on the 97155 line to bypass automated bundling edits.

We see practices applying none of these modifiers, or applying them inconsistently across payers, which creates a denial waterfall that compounds each billing cycle.

Place of Service Codes: The Overlooked Variable

POS code mismatches between 97153 and 97155 on the same claim are triggering denials at several major commercial payers including Cigna, UnitedHealthcare, and Aetna. If 97153 is billed under POS 12 (home) but 97155 is billed under POS 11 (office) because the supervising BCBA reviewed records at the clinic, you will receive a CO-4 or CO-97 denial on the 97155 line at a rate we estimate above 40% with these three payers based on current claims data in our system.

The rule of thumb we follow: both lines must share a POS code that reflects where the patient received the service. If the RBT is in the home (POS 12), the BCBA’s supervision component, even if partially remote, must be billed under POS 12 with the appropriate telehealth modifier if applicable. Splitting POS codes on concurrent lines is a payer edit trigger, not a billing best practice.

How to Build an Appeal That Actually Gets Paid

For concurrent-service denials that have already occurred, we are seeing appeal overturn rates between 62% and 78% when the appeal packet includes all three of the following elements:

• A clinical narrative from the supervising BCBA that specifies the minutes of direct protocol modification, the distinct clinical decision made during the 97155 period, and how that decision differed from the ongoing 97153 session protocol. Vague supervision logs are the primary reason appeals fail on reconsideration.
• The payer’s own ABA coverage policy printed and cited with specific language that permits concurrent billing of 97153 and 97155 when rendered by separate providers. Most commercial payers have this language. Most practices never cite it.
• Corrected claims with accurate modifier stacks submitted simultaneously with the appeal letter. Filing the appeal without the corrected claim means you win the appeal and still do not get paid because the original claim remains in a denied status.

Practices that are dealing with broader payer underpayment patterns alongside concurrent-service denials should also review how medical necessity language is being weaponized across claims. Our post on MHPAEA parity appeals and how behavioral health practices are leaving money on the table covers how to invoke federal parity law when payers impose ABA-specific limitations they do not apply to comparable medical services.

The Authorization Layer Most Practices Ignore

A significant share of 97153 and 97155 concurrent denials in 2026 are not billing errors at all. They are authorization mismatches. Many payers authorize 97153 units and 97155 units in separate pools with distinct authorization numbers. When both codes are billed on the same claim and the billing team applies only one authorization number, the second line adjudicates without a valid auth and denies as CO-197 (precertification or authorization absent).

What we now require in our ABA client onboarding is a payer-level authorization matrix that maps each CPT code to its own authorization number, its approved unit count, and its concurrent billing rules as defined in the actual authorization letter, not just the fee schedule. This is painstaking work upfront, but it eliminates an entire category of preventable denial that we estimate costs the average ABA practice with $1.5M to $3M in annual revenue between $90,000 and $180,000 per year in write-offs or unworked denials.

What a Clean 97153 and 97155 Claim Looks Like Before Submission

Before any concurrent claim leaves the clearinghouse, the following conditions should be verified at the claim level:

• Separate rendering NPI numbers on each service line (RBT NPI on 97153, BCBA NPI on 97155)
• Matching POS codes on both lines reflecting the patient’s service location
• Correct modifier stack applied per payer-specific rules (HO, HN, 59, XP, 95, GT as applicable)
• Separate authorization numbers on each line when the payer authorizes codes independently
• Session notes that document the start and stop times of the BCBA’s direct involvement for 97155 as distinct from the RBT’s session time for 97153
• Unit counts that do not exceed the payer’s per-day maximum for either code (Medicaid plans in many states cap 97155 at four units per day regardless of medical necessity documentation)

This pre-submission checklist, applied consistently, is what separates practices sitting at a 12% to 15% denial rate from practices sitting at 4% to 6%.

Take the Next Step: Get a Free 30-Day Denial Audit

If your practice is billing both 97153 and 97155 and your denial rate on those codes is above 10%, there is recoverable revenue sitting in your payer queue right now. At Revenant Care Group, we offer a free 30-day denial audit specifically for ABA and behavioral health practices that want a clear picture of where claims are leaking and what the recovery path looks like. No obligation, no vague recommendations. You get a code-level breakdown with a prioritized action list. Book your free audit on our calendar and let us show you what your concurrent-service claims are actually worth.