The American Medical Association released the 2027 CPT code set on September 9, 2026, and one of its more disruptive changes has nothing to do with AI documentation rules or laboratory codes — it’s a restructuring of adaptive behavior (ABA) coding that takes effect January 1, 2027. Six codes are added, two are deleted, and one of the most heavily billed codes in behavioral health, 97155, changes scope entirely. For coding and compliance teams in behavioral health and multi-specialty practices that bill ABA services, this is less a code-set refresh than a compliance countdown.
What Changed in the CPT 2027 ABA Code Set
The update expands adaptive behavior services from 10 codes to 14. Two new assessment codes, 97148 and its add-on 97149, join two new treatment codes, 97159 and add-on 97160. A new code, 97173, captures “treatment with analysis by a qualified healthcare professional” — work that used to be bundled into 97155. A sixth new code, 97180, covers non-face-to-face services: data review, clinical decision-making, and technician training that previously had no dedicated billing pathway.
The deletions are just as consequential for coders who’ve built claim logic around the old set: Category III temporary codes 0362T and 0373T are retired, replaced by the new permanent Category I harmful-behavior codes (97148/97149 for assessment, 97159/97160 for treatment). Temporary codes disappearing in favor of permanent ones is routine; what’s not routine is the scope change to 97155 itself.
The Code Everyone Bills Is Splitting
CPT 97155 is one of the most frequently used codes in ABA billing, and as of January 1 it no longer means what it meant on December 31. The code now covers only “direction of technician and analysis” — the supervisory and clinical-oversight component. The direct-treatment component that used to be billed under the same code moves to the new 97173. Practices that have been billing 97155 for a combined supervision-plus-treatment encounter will need to split that work across two codes, with two sets of documentation requirements, starting on the same claim.
That split is where the compliance risk concentrates. A handful of old-to-new mappings coders and auditors should have memorized before year-end:
- 0362T (assessment) → replaced by 97148 (primary) and 97149 (each additional technician)
- 0373T (treatment) → replaced by 97159 (primary) and 97160 (each additional technician)
- 97155 (combined supervision + direct treatment) → splits into 97155 (supervision/analysis only) and the new 97173 (direct treatment by a qualified professional)
- Non-billable care-coordination work (data review, technician training, clinical decision-making) → now billable under the new 97180
Why This Is a Compliance Problem, Not Just a Billing Update
A code-set change that alters what an existing, high-volume code covers creates two distinct exposure windows that a simple crosswalk update won’t fully close.
Claims Filed on Either Side of January 1
Dates of service before January 1, 2027 must still use the old code definitions; anything on or after must use the new ones. For practices that batch-submit claims or have any lag between service date and claim submission, the risk isn’t using a deleted code — payers will simply reject that — it’s billing 97155 under its old, broader scope for a date of service that actually falls under the new, narrower definition. That’s a documentation-to-code mismatch an auditor can flag well after the fact, not a claim-scrubber rejection caught at submission.
Payer Adoption Won’t Be Uniform
CMS is expected to finalize its own adoption of the 2027 code set in November 2026, which leaves a narrow window before the January 1 effective date. Commercial and Medicaid managed-care payers don’t necessarily move on the same clock as CMS, and coding teams that bill across multiple payers should not assume a single go-live date applies to every contract. Confirming each payer’s effective date — rather than assuming CPT’s calendar governs every claim — is itself a compliance task, not an administrative afterthought.
The 15-Week Clock
According to reporting on the update, professional associations including the Association for Behavior Analysis International, the Association of Professional Behavior Analysts, and the Council of Autism Service Providers began hosting webinars on the changes this September, and roughly 15 weeks remain from the code set’s release to the January 1 effective date. That’s the realistic window practices have to update EMR order sets, payer contracts, prior-authorization templates, and internal coding guidance — a tight timeline given that CMS’s own final rule isn’t expected until November, leaving only about six weeks between federal confirmation and go-live.
What Coding and Compliance Teams Should Do Now
Waiting for the CMS final rule before touching any system configuration means compressing months of preparation into weeks. Coding and compliance leads billing ABA services should treat the current AMA-published code set as the working baseline now: update EMR charge masters and order sets to reflect the 97155/97173 split, flag any claim workflow that still references 0362T or 0373T for removal, and confirm each major payer’s own effective date in writing rather than assuming alignment with CMS.
The underlying challenge is one static coding rules handle poorly: a single high-volume code changing scope mid-lifecycle, with two valid definitions in play depending on date of service. That’s exactly the kind of date-sensitive, context-dependent logic that’s error-prone in manual workflows and where reporting on the AMA’s 2027 CPT release underscores how much operational work sits behind a seemingly routine code-set update. Automated coding platforms that apply the correct code definition based on date of service — rather than relying on staff to remember which rule set applies to which claim — reduce exactly this kind of post-payment audit exposure. That’s the problem Medikode’s automated medical coding platform is built to solve: applying current code logic consistently across every claim, so a mid-cycle code-set change doesn’t become a retroactive audit finding.