SHELBURNE — By a two-vote margin, Special Town Meeting voters narrowly backed a new Mohawk Trail Regional School District assessment formula that includes out-of-district and School Choice students from each town in determining that town’s share of expenses.

Shelburne’s 26-24 vote means the new assessment formula and related regional agreement changes have the backing of six Mohawk Trail member towns, leaving Heath and Plainfield to take up the measure again in future meetings. All towns must approve the amended district agreement before it can take effect.

Per the district’s regional agreement, town assessments are currently calculated by counting the number of students enrolled on a five-year rolling average in the Mohawk Trail Regional School District. This is called “complete enrollment.” Depending on the ratio of students enrolled over that five-year period, each town pays its share of the school district’s capital costs and operating expenses.

Should a new town assessment formula take effect, it would better align with the state’s funding formula, called “foundation enrollment,” by factoring in School Choice students, residents who opt to attend a charter school and out-of-district special education students.

On Wednesday, the Finance Committee opposed voting for the regional agreement changes because the definition of “capital costs” now includes “maintenance” — including the purchase of vehicles.

“Changing the definition of capital to include maintenance is a significant change here,” said Finance Committee member James Burnham. “Vehicles are now a capital cost. How are we going to apportion a vehicle?”

“A ‘no’ vote tonight is not a vote against the schools,” Burnham continued. “There is no compelling reason to pass this tonight.”

At 26-24, the vote was so close that a hand count was taken at least four times.

The only other item on the Special Town Meeting warrant was a citizen’s petition article to approve an “own-our-streetlights” option. The article was passed over until Annual Town Meeting in May, while more information about the proposal is being studied.