TREMONT — Selectmen in a 5-0 decision Tuesday turned down a request to support Mount Desert selectmen in their attempt to change the funding formula for Mount Desert Island High School.

A presentation on the funding formula by Union 98 superintendent Rob Liebow preceded the selectmen’s vote. The formula determines how much each of the four Mount Desert Island towns contributes annually to the high school budget.

The Mount Desert selectmen are seeking to change the formula because they believe Mount Desert residents unfairly pay a higher cost per pupil than the residents of the other towns. Their request also has been turned down by selectmen in Southwest Harbor and town councilors in Bar Harbor.

According to Mr. Liebow, the formula has been unchanged since it was set up in the mid-1960s to create the regional high school. Under the formula, 33 percent of funding is based on the number of students a town sends to the school, the remaining 67 percent is based on the valuation of the town for property tax purposes.

As a result, the per-student cost per town varies. Estimated per-pupil costs for the 2009-2010 school years are $11,784 for Tremont, $12,600 for Southwest Harbor, $11,509 for Bar Harbor and $27,094 for Mount Desert.

Mount Desert has always paid more per student than other towns because of its higher valuation, Mr. Liebow said. There are about 600 properties in the town that are valued at $1 million or more, he said. In Tremont there are about 100 properties in that range.

“That gives a lot of tax value to the town,” Mr. Liebow told the selectmen. As such, a resident of Mount Desert actually pays less than his or her counterpart with a similarly valued property in the other towns, he added.

The question becomes whether per-student costs should be equitable or whether to high school should be considered a mutual resource and some towns have a greater ability to contribute financially to that resource, Mr. Liebow said. “That’s really the gist of the argument.”

Mr. Liebow said he subscribes to the belief that the high school is a “common endeavor and common effort that everybody agreed to years ago” and the funding formula should remain as it is.

“I think of the formula as being fair because it treats categories of taxpayers the same,” he said.

Selectman Scott Grierson said he has to keep the best interests of the town in mind and that he might feel differently about the formula if he represented Mount Desert.

“It all boils down to what’s the best deal for Tremont,” he said. If any changes are to be made to the formula it should be to base it completely on valuation of the town, which would favor Tremont even more, he said.

Mr. Grierson made the motion to withhold support for the funding formula change.

Changing the funding formula would require an act of the state Legislature.