That same year the St. Louis Public Schools sued the city’s charter schools for $42 million that the charter schools had received from a sales tax that funds a court-ordered desegregation program. The district said the tax was solely intended for its schools.

“Both of those things put us in a position saying we need to have a much better understanding of what are the pieces that go into the local funding and what is it charters are receiving and not receiving,” Thaman said. “That took a very long time to unravel.”

Dorson says there’s a limited amount of money that can be directed away from a public district to charter schools. If that is used up, the department may not be able to fully fund charter schools. This is becoming evident in Kansas City, he said, where more and more students have been choosing charter schools.

“If the charter school enrollments continue to rise, there might be a point in time in the future where all the state aid that Kansas City (public schools) would be entitled to is used and diverted to charter schools and there would be no other revenue stream to be able to pay the additional money to charters.”