The amount of money that could go toward Gov. Bill Lee's controversial school voucher program could exceed $330 million by 2024, although not all of that would be new tax dollars, according to a new fiscal analysis.

Lawmakers gave final approval Wednesday to the education savings account program after adopting a conference committee report that worked out differences between the House and Senate versions of the legislation.

Still, the debate was not always smooth as confusion over the fiscal analysis forced Senators to delay their vote. A new, updated analysis was later released.

At issue is exactly how money for the program is accounted for in the fiscal analysis.

The education savings accounts provide public money for parents who unenroll a student from their school district and allow them to use the funds on private school or other education-related expenses.

The program will apply to Davidson and Shelby counties. The state would shift money away from Tennessee's Basic Education Program to fund the education savings accounts. That's all existing funding, through a combination of state and local sources.

Then an equal amount of money would go into a new school improvement fund for three years starting in fiscal 2021-22 when students can begin enrolling.

That new fund would provide grants to Metro Nashville Public Schools and Shelby County Schools to make up for the money that the districts lose when the students participating in the ESA program leave a public school.

That's new money — $165 million over three years based on full participation in the program. There would also be administrative costs.

Lawmakers and administration officials said the original fiscal analysis improperly counted money twice.

The program was set to cost as much as $125 million in new money by 2024 under early estimates.

House Speaker Glen Casada's chief of staff Cade Cothren said the majority of the money for the program is funded through the Basic Education Program, aside from the grants.

"The program is paid for by those counties through the BEP," Cothren said. "It's not new funding."

The program would begin in the 2021-22 school year with 5,000 students eligible to use the program in Davidson and Shelby County schools. It would eventually cap at 15,000 students.

On average, the program will shift $7,300 in public funds to parents for private school or other education costs such as textbooks or tutoring.

In Davidson and Shelby counties, the BEP only covers about half the cost of educating a student, with local dollars making up the difference.

Over the course of three years, according to the fiscal analysis, the amount of state and local funding going toward the new program — including the shifted BEP funding and the grants — would be:

$73,762,400 in fiscal year 2021-22.

$110,643,400 in fiscal year 2022-23.

$147,524,600 in fiscal year 2023-24.

The fiscal analysis assumes the program will be used fully by every eligible student. The compromise legislation says the program wouldn't grow unless participation reaches 75% of the cap.

The compromise bill requires participating students take the standardized math and English exams.

It also includes a severability clause. The clause would mean if a judge were to determine the program's limitation to Shelby and Davidson counties was unconstitutional, the program would end.

Democrats argued on Wednesday morning that the clause would not do what supporters say.

The bill also contains a provision that prohibits local education boards from filing a lawsuit over the program. That prohibition, however, does not extend to other interested parties.

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Reach Joel Ebert at jebert@tennessean.com or 615-772-1681 and on Twitter @joelebert29.