BELGRADE — Of the towns in Regional School Unit 18, Belgrade would pay the biggest bill if the district’s budget plan passes in its current form.

The district has proposed a spending plan of $38,655,456 for the 2019-2010 fiscal year that starts July 1. That is an increase of $1,075,066 — or 2.86 percent — from the current spending of $37,580,390.

Of that $38.65 million, Belgrade’s share of the bill would be $6,465,058, or 16.72 percent. That is an increase of $257,118.62 from the 2018-2019 spending plan, or 3.98 percent more than its current share of $6,207,939.

Oakland would have the second-biggest share, $5,828,970, or 15.08 percent; China would pay $5,038,575 (13.03 percent); Sidney, $4,370,039 (11.31 percent); and Rome, $2,123,761 (5.49 percent of the bill).

School spending is being driven largely by payments the district is making on a $13.9 million bond to fix facilities and build an athletic complex. Voters approved that bond in 2017.

Three factors determine how much each of the towns contribute to the school’s spending plan.

First, Essential Programs and Services determines how much each town must raise through its tax rate.

Second, towns must pay local debt in the district — this year it is primarily associated with the $13.9 million bond — which is divided among the towns based on a cost-sharing formula.

Finally, additional local funds are split up among the town based on the same cost-sharing formula, which is determined by population and state valuations.

The state valuation of Belgrade is $633,350,000, which has the highest valuation in the district. In comparison, China’s valuation is $417,850,000; Oakland, $513,250,000; Rome, $328,500,000; and Sydney, $413,000,000.

RSU 18 Superintendent Carl Gartley updated Belgrade selectmen on the budget at their meeting Tuesday. He expects the spending plan, as it is currently drafted, would cost Belgrade taxpayers $24.96 more per $100,000 of assessed valuation than last year.

Gartley said the $13.9 million bond has been broken into three phases. The first looks at energy performance of the district facilities; the second is for improvements at the athletic complex at the high school, which are almost complete; and the third is for capital projects.

Those capital projects hadn’t been funded previously because of declining state subsidies.

“The facilities took a lot of hits and were deferred,” he said.

Among those updates, Belgrade Central School is having repairs and improvements made to the front entrance. He said the work is under contract with ProSeal, and it’s scheduled to start in late June.

The town’s new tax rate will be calculated when the Kennebec County government and Regional School Unit 18 budgets are final. The district also is awaiting word on what its state funding will be for next fiscal year.

Belgrade’s tax rate for the current fiscal year, which ends June 30, was $14 per $1,000 of assessed valuation. On a $100,000 home, taxes are $1,400 before any exemptions. At Town Meeting on March 16, residents approved a $3,356,981 municipal spending plan, an increase of 4.3 percent from the current budget.

A public hearing is scheduled for 6 p.m. May 16, at the Messalonskee Performing Arts Center, 131 Messalonskee High Drive in Oakland. A budget validation referendum vote will take place in all towns in the district on June 11; in Belgrade, it will take place at the Center for All Seasons.