The measure would begin directing about $1.4 million next fall to the 40 charter schools across the state.
The schools will get a share of tax dollars - based on a funding formula that factors in the total number of school levies and the number of public school students in the state - to support facilities and maintenance costs.
The Senate passed a bill on a 20-15 vote Thursday. The annual payout would grow to $2.1 million in the second year, and even more in subsequent years.
The measure has already passed the House and is en route to Gov. Butch Otter.
Proponents say the money - estimated in the first year as $34,000 per charter school - is essential to help the nontraditional schools survive and levels the playing field with traditional public schools. Unlike traditional schools, charters don't have the authority to ask local voters to approve bond levies to offset expenses, build new schools or pay for remodels.
Sen. John Goedde, R-Coeur d'Alene, said chipping in funding is an important way to safeguard charters' future, adding the state's public schools already receive a significant chunk of change from the state.
"We fund traditional schools as if they were a Chevy Malibu, and we fund charter schools as if they were a Chevy Nova," he said.
But Republicans and Democrats who opposed the bill criticized sending money to charters when traditional schools are in just as much need.
Republican Sen. Shawn Keough of Sandpoint, who sat on the Senate Education Committee in 1998 when the state originally authorized charter schools, said they were designed as a testing ground for new education techniques that could be applied to the state's K-12 system.
The Senate approved another bill Thursday allowing public universities to establish charter schools.