“Hopefully there would be more choices,” Wieske said. “The result would be problematic if they ended up with just one operator.”

Wieske said he did the study for Madison-based CTA Strategies led by Andrew Hysell, who declined to say who paid for it. Hysell said he had worked on education policy focusing on rural schools and raised funds from the insurance industry and public education organizations.

The Milwaukee School District would save the most, the study found, at $ 23 million without an employer contribution to the HSA, followed by Green Bay, with $ 15.1 million, and Fond du Lac, with $ 8.2 million.

The Madison School District would save $ 1.9 million, a much smaller amount per person, likely because the district is already getting a relatively good deal in the competitive Dane County HMO market, Wieske said. The La Crosse district would lose $ 2.2 million and Kenosha would lose $ 9.2 million, also because they have relatively low costs right now, Wieske said.

Without any employer contribution to the HSA, McFarland District would save $ 434,000, Middleton-Cross Plains would save $ 1.4 million, Monona Grove would save $ 964,000, Oregon would save $ 1.2 million, Sun Prairie would save 2 , $ 5 million, Verona would save $ 388,000 and Waunakee would save $ 1.2 million, according to the study.