ABA supervision ratios are becoming billing rules: Indiana, Massachusetts and what CMS recommends

A supervision ratio can mean two things. The BACB requires an RBT to receive ongoing supervision for at least 5% of the hours spent providing behavior-analytic services each calendar month, at each organization¹. That is a credential rule, covered in our guide to RBT supervision in 2026. A payer ratio is a condition of payment, and Indiana counts it for each child, each month⁴.

The CMS toolkit draws the same line: the 5% is a minimum for the credential, tied to the RBT’s service hours, not a recommended level for every case². Meeting it does not show you meet a payer’s ratio.

Indiana announced on February 26, 2026 that from April 1 it requires at least one hour of supervision by a BCBA or another IHCP-approved clinician for every eight hours of technician-delivered ABA³. A bulletin of April 28 answered questions and set out how it is measured⁴, and IHCP’s 2026 training slides, in a file dated October 2026, still state the rule⁵.

• Per child, per month. It is measured monthly for each member and not aggregated across technicians or members⁴. With fewer than eight RBT hours, a proportional amount is still due⁴.
• What counts. Billable and nonbillable supervision count if documented, specific to the child and clinically relevant, such as reviewing treatment fidelity or session notes⁴. Scheduling, performance reviews and general staff meetings do not⁴.
• 97155 counts only as direction. Billed for observation, protocol evaluation or the clinician delivering treatment, without actively directing a technician, it is not counted, even if billable⁴.
• Telehealth supplements. It is allowed with modifier 95 but meant to supplement, not replace, the majority of in-person services⁴.
• Audit. The rule is subject to claim audit and postpayment review. A failure may bring claim adjustments, recoupment or other administrative action, and records must be kept and produced on request⁴.

As the Inspector General describes it, MassHealth does not issue ABA regulations on this point: it approves each managed care entity’s performance specifications, which require at least one hour of case supervision per 10 hours of direct service⁶. In March 2024 that office tested the rule with encounter data, comparing technician hours billed as 97153 with supervision billed as 97155⁶.

The average looked fine: one hour of supervision per 7.78 hours of service. Yet 108 of the 562 providers reviewed, all serving at least five members, exceeded 10:1, and the OIG estimated $16,761,445 in payments over the ratio⁶. In its example, a provider at 20:1 that was paid $100,000 is counted at $50,000⁶. The report recommended that MassHealth and its plans review encounter data to decide on recoveries, and no source we found says what was recovered⁶. It also noted the shortage of licensed analysts and said it does not excuse missing supervision⁶.

A current Optum specification for MassHealth adds a ceiling: supervision of no less than 10% of direct service hours and not above 25% without documented clinical rationale⁷. Each plan publishes its own.

The toolkit reports that clinical guidelines recommend about 10% to 20% supervision relative to direct treatment hours, and it suggests states ensure ratios of 1 to 2 hours per 10². It tells states to monitor technician-to-supervisor ratios beyond expected norms, to include supervision logs in required documentation and to use unannounced site visits to validate staffing or supervision ratios². AHCA’s minutes list “Establish supervision ratios” among the recommendations CMS’s presenter emphasized to Florida’s task force on August 31¹⁴.

The number is contested, and the sources we reviewed present it as guideline or payer policy, not as the result of outcome studies. The toolkit itself says needs vary and encourages providers not to restrict supervision to the minimum². In Nebraska, providers objected to the 10% to 20% in the state’s definitions, and the state replied that supervisors must be actively involved, especially as it was relaxing RBT training requirements⁸.

The toolkit cites its 10% to 20% to CASP’s third edition (April 2024), which is released only under a license agreement, so this article relies on the toolkit²⁹. A PDF that CASP hosts publicly is the 2020 second edition, which put the general standard at two hours per 10¹⁰. If someone quotes CASP’s ratio, ask which edition.

The coverage policy prints no supervision ratio. It requires supervision of BCaBAs and RBTs under CASP’s current practice standards and the supervision plan of the approved behavior plan, which names the authorized supervisors¹¹. A supervisor may be paid for observing a supervisee, who is not paid for the same time¹¹. To enroll an RBT, Florida asks for proof of supervision, updated when it changes¹³.

AHCA’s October 5 slides describe the current policy as deferring to the BACB’s requirement of at least 5% of the RBT’s service hours. They list aligning supervision with practice guidelines at 10% to 20% as a possible future option, along with plans reporting supervisees per supervisor and billing that links supervision¹⁵. These are options, not decisions: recommendations are due December 31, 2026¹⁶. The policy points to CASP’s standards while AHCA’s slide reads it as deferring to the BACB, so ask each plan which one it audits against.

Indiana’s rule has applied since April 1, 2026, and none of the later ABA bulletins we read changes it³⁴⁵. The Massachusetts findings date from 2024, and the Optum file, dated January 2026, is newer⁶⁷. In Florida, the December 2024 policy has been in force since February 10, 2025¹¹¹². Rules differ by payer and change: this is not legal or billing advice, so ask your plan for its supervision definition in writing.