The Illinois Legislature on Tuesday approved a school funding overhaul that supporters hailed as “historic,” saying it will increase aid to all of the state’s more than 800 districts and eliminate large disparities between rich and poor schools.

The Senate voted 38-13 to send the measure to Republican Gov. Bruce Rauner, who has said he’ll sign it quickly to get money to districts starting a new school year. The House passed the bill late Monday.

Democratic Sen. Andy Manar, the bill’s sponsor, said the plan will fund schools fairly “for the first time in decades.”

“There will not be another generation of students that are subjected to inequity — the worst in the country — after this bill becomes law,” he said. “That’s something worth saying today.”

Lawmakers have tried unsuccessfully for years to replace the current system. This year’s state budget required for the first time that the formula be changed, and provided an additional $350 million to help pay for it.

No money can go to districts, however, until a new plan is in place. Although school officials have said they will be able to open classrooms for the new school year, many districts have worried they would run out of money if a plan wasn’t approved soon.

The legislation passed Tuesday also provides $75 million in tax credits for people who contributed to private school scholarships.

Teacher unions and some school officials oppose the credits, saying taxpayer money shouldn’t be used to fund private schools. They fear the scholarships — which lawmakers say would benefit as many as 10,000 students — will reduce enrollment at public schools, some of which are struggling to maintain enough students to stay open.

“A parent has the right to choose a private education for their child,” said Superintendent Andrea Evers from downstate Cairo, a poor district which has lost population. “It should not be on the backs of taxpayers.”

Still, others said having more cash was critical.

Edwin Shoemate runs a roughly 515-student district in southern Illinois’ Cobden, which relies on the state for much of its $4.3 million annual budget.

Shoemate anticipates receiving roughly $180,000 more, enough to pay for about three more teachers and to add back elementary school art.

Some charter school teachers wonder if students at their schools will leave for private schools thanks to the scholarship program. Charter schools are publicly-funded, privately-run schools that have been in Illinois for nearly 20 years, mostly in Chicago. The parents of children in charter schools might be predisposed to look for school choices.

Chris Baehrend, president of the Chicago Alliance of Charter Teachers and Staff Local 4343, which represents more than 1,000 teachers at some of the city’s charter schools, said the union’s members are worried. Charter schools in the city are already grappling with budget cuts and fierce competition for students as enrollment in CPS declines.

“Parents who have students in charter schools should know that vouchers will do damage to our schools, resources will be taken out of classrooms, causing budget cuts and layoffs and increasing class sizes,” he said. 

But the Illinois Network for Charter Schools has been noticeably quiet about the scholarship program. The statewide membership organization, however, did praise the new school funding formula.

Josh Cunningham, education program manager at the National Conference of State Legislatures, said Illinois’ program will be small compared to other states that have similar initiatives. Florida’s serves more than 100,000 students. But he noted that Florida’s program started out small and has grown every year. 

He said the financial effect on public schools is slow, but particular schools in large urban districts and smaller rural districts could feel the impact.

The tax credit program will expire after five years if lawmakers don’t extend it. The credits would be worth 75 percent of a taxpayer’s annual contributions to a scholarship fund, with a maximum credit of $1 million annually. The money may be donated to a specific school but not a specific student.

Students receiving the scholarships must have a household income of less than 300 percent of the federal poverty level, or about $73,000 annually for a family of four.

Under Illinois’ current school funding system, districts must rely heavily on property taxes to fund schools. That’s created large differences in funding levels, with some wealthier districts spending four times more per student than districts with less property tax wealth.

Under the new plan, the state will determine how much money each district needs to adequately educate its students, taking into consideration the number who live in poverty, are English learners or need special education services. The state then looks at how much money the district is able to generate from property taxes, and directs aid first to districts that need it to reach the spending target.

The legislation also provides money to help Chicago Public Schools make payments to its teacher pension funds, as Illinois does for other districts, and gives districts relief from some state mandates, such as allowing them to offer fewer days of physical education each week.

WBEZ’s Sarah Karp contributed to this report.