100 Out of 100

MADISON, WIS. — The HHS Office of Inspector General’s audit of Wisconsin’s Medicaid ABA payments followed the same methodology used in Indiana, Maine, and Colorado: auditors selected a sample of enrollee-months, reviewed the underlying claims and documentation, and assessed compliance with federal and state requirements. The result was identical to every other state in the series: all 100 sampled enrollee-months contained at least one improper or potentially improper payment. The error rate was 100 percent.

Wisconsin’s fee-for-service Medicaid payments for ABA services grew from $39.9 million in 2018 to $53.7 million in 2022 — a 35 percent increase over four years. While the growth rate was more modest than Colorado’s 172 percent or Indiana’s explosive trajectory, the audit found the same categories of billing errors: missing or inadequate documentation, services billed for non-therapy time, technicians lacking required credentials, and supervision requirements not met.

The OIG recommended that the Wisconsin Department of Health Services refund $12.3 million (federal share) to the federal government for FFS Medicaid ABA payments that did not comply with requirements. Additionally, auditors flagged an estimated $62.3 million in potentially improper ABA payments and recommended that the state exercise reasonable diligence to review those claims and refund the federal share of any confirmed improper amount.

The audit also carried a finding that underscored the depth of Wisconsin’s oversight failure: the state’s Medicaid program had never conducted a single post-payment review of ABA claims since the program began in 2016. That represents nearly a decade of billing without any state-level scrutiny of whether claims were legitimate. ABA providers in Wisconsin operated in an environment where claims were processed and paid without any retrospective verification that the services billed were actually delivered, properly documented, and performed by qualified staff.

Wisconsin’s Medicaid program had never conducted a single post-payment review of ABA claims since the program began in 2016 — nearly a decade of billing without any state-level scrutiny of whether claims were legitimate.

The OIG’s Five Recommendations

The OIG made five specific recommendations to Wisconsin. First, refund the $12.3 million federal share for confirmed improper payments. Second, review the $62.3 million in potentially improper payments and refund the federal share of any additional improper amounts identified. Third, update guidance for CPT code 97155 to require documentation on how clinical issues were resolved or what changes were made to the treatment protocol. Fourth, provide additional guidance to ABA facilities about documentation requirements, including the information needed in session notes and state signature requirements. Fifth, periodically conduct statewide post-payment reviews of Medicaid ABA payments, including reviewing session notes, and provide training where errors are identified.

The recommendations follow a pattern established in the Indiana and Maine audits: refund, clarify guidance, and implement ongoing oversight. The post-payment review recommendation is particularly significant because its absence was the single largest systemic failure identified in the audit. Without any retrospective review of claims, there was no mechanism to identify or correct billing errors until the federal OIG intervened.

Wisconsin’s Partial Concurrence

Wisconsin’s response to the OIG audit is instructive because it reveals the strategy states are using to resist federal audit findings. The state partially concurred with the OIG’s recommendations — a posture that acknowledges the existence of compliance problems while disputing the specific dollar amounts and some of the methodological conclusions.

The partial concurrence pattern allows states to accept the need for improved guidance, documentation standards, and oversight mechanisms while pushing back on the refund amounts. States argue that the OIG’s sampling methodology extrapolates error rates from small samples to large populations of claims, potentially overestimating the total improper payment amount. They also argue that some claims flagged as improper may have been for services that were actually delivered and clinically appropriate but lacked adequate documentation — a paperwork failure rather than a billing fraud.

The distinction between documentation failure and billing fraud matters because it affects both the legal exposure of individual providers and the policy response. Documentation failures can be addressed through education, training, and better technology. Billing fraud requires enforcement, recovery, and potentially criminal referral. The OIG’s audits do not distinguish between these categories; they flag claims as improper or potentially improper based on compliance with documented requirements, regardless of whether the underlying service was actually delivered.

For ABA providers in Wisconsin and nationally, the partial-concurrence pattern offers cold comfort. States may dispute the specific refund amounts, but they are agreeing to the corrective actions that will fundamentally change how ABA claims are reviewed and paid. The era of submitting claims without any expectation of post-payment review is over. The era of operating with minimal documentation because no one was checking is over. The audits have established a new baseline for what compliance looks like, and every state — whether audited yet or not — will eventually be held to that standard.

Wisconsin’s $18.5 million audit finding is the smallest of the four completed state audits, reflecting the state’s more modest ABA spending levels. But the 100 percent error rate — identical to Indiana, Maine, and Colorado — sends the same message: the compliance failures in ABA billing are not proportional to spending levels. They are structural features of an industry that grew faster than the oversight systems designed to govern it.

For compliance officers, clinical directors, and practice owners, the Wisconsin audit is a case study in what happens when a state has no post-payment review process, no systematic credential verification, and no documentation standards enforcement. The lesson is not that Wisconsin failed uniquely. The lesson is that most states have similar gaps, and the OIG is systematically identifying them. The question is not whether your state will be audited. It is whether your organization can pass the audit when it comes.

AT A GLANCE

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