A new formula to share costs among Regional School Unit 12’s eight towns will get a public airing at hearings this week and next.

Similar to a proposal that stalled at a school board meeting last winter, the latest plan would likely benefit Westport Island and Wiscasset most and have the largest negative impact on Palermo, Somerville and Windsor. The actual cost shift, however, is less extreme.

RSU 12 board members said they think the new proposal is fairer because every town will pay the same amount per student and can count the subsidy it receives from the state toward its contribution to the school district. “The view we’ve taken is that if the RSU is asking every town to pay the same amount per student, you can’t get any fairer than that,” board Chairwoman Hilary Holm said.

The board approved the plan on a first vote and will consider input from three public hearings: Tuesday in the Wiscasset High School library, Thursday in the Windsor School cafeteria and Wednesday, Sept. 5, at Somerville School. All the hearings are scheduled for 7 p.m.

If public input is mostly positive, the school board will approve it as is or make minor changes at its Thursday, Sept. 13, meeting before placing it on the November ballot for final voter approval, Holm said.

RSU 12 includes Alna, Chelsea, Palermo, Somerville, Westport Island, Whitefield, Windsor and Wiscasset. The district splits costs based on percentages derived from each town’s school spending in 2008-09, the year before the school district formed.

Both the formula and efforts to change it have caused dissension in RSU 12. In Westport Island and Wiscasset, which are developing plans to withdraw from the district, some residents think they are paying more than their share.

And although the earlier proposal died without a vote from the school board, the fact that it would have steeply increased Windsor’s taxes was enough to make selectmen wonder whether to also consider withdrawing. The first proposal calculated a new percentage split based on each town’s population and student count.

People in some towns, such as Westport Island, complained that they would have to pay much more per student than their neighbors. Meanwhile, people in towns such as Windsor said they should get credit for the state money they bring into the district, thereby reducing the amount RSU 12 must collect in local taxes.

Excluding debt service, RSU 12 will receive $8.3 million in state subsidy to support a $23.8 million budget this year. State subsidy is based on property valuation and varies widely by municipality. This year, for example, RSU 12 will receive $2.6 million for Windsor’s 377.5 students but only $871,271 for Wiscasset’s 449.5 students.

The new formula multiplies a town’s number of resident students by RSU 12’s overall operating cost per student to determine each town’s contribution. Towns will count their own state subsidy toward their contribution and raise the balance through local taxes.

If RSU 12’s cost per student is $10,000 and a hypothetical town has 440 students, the town’s contribution is $4.4 million, according to the district. If RSU 12 receives $2.3 million from the state on the town’s behalf, that town must raise the remaining $2.1 million from its taxpayers.

Finance committee Chairman Jerry Nault, who lives in Windsor, said the new plan should be easier to understand.

“I think we were attempting to model our former approach on other existing formulas from other RSUs,” Nault said. If the new formula were applied to this year’s budget, Alna, Chelsea, Westport Island and Wiscasset would save money. Palermo, Somerville, Whitefield and Windsor would pay more.

Nault said there are too many factors in flux to create helpful projections. He hopes the plan will appeal even to people who could have to pay more, such as his fellow Windsor residents.

“I hope that people will ask, ‘Is this a fairer way?'” he said. “And if you answer yes, then we’ve done our job. I’m going to ask them to reach for the higher standard here.” To make the transition smoother, the board also has recommended changes to the safety net portion of RSU 12’s consolidation agreement so that towns can ease into paying more. Some towns would essentially subsidize others for the first three years, which Nault said is the only alternative to abrupt cost-sharing changes.

“Most of us agree that in order to be fair for each other, if we’re going to change the formula, and there are going to be towns that save money and towns that are going to have spend more money, we need to help those towns that spend more money ease into their new obligation,” said Holm, who lives in Whitefield. Wiscasset board member Eugene Stover, who has called the safety net socialist, voted against the proposal.

Holm said most of her conversations about the plan have been in the southern part of the district, where people are excited because they anticipate paying less. She looks forward to hearing from other residents at the Windsor and Somerville hearings.