WINDSOR — A new cost-sharing formula could be a hard sell in the northern part of Regional School Unit 12, where towns are likely to face tax increases.

The formula, which the school board will consider at its Thursday, Sept. 13, meeting, would benefit Westport Island and Wiscasset and have the greatest negative impact on Palermo, Somerville and Windsor.

The plan could appear on the ballot in November, and if voters approve it, it would apply to next year’s budget. The plan has been presented at two public hearings, and another is scheduled for 7 p.m. Wednesday at the Somerville school.

It is not possible to make definite projections about how the formula would affect the RSU 12 towns because town contributions will be determined by this year’s enrollments and next year’s budget.

If Whitefield must pay more to the RSU, it will mean a tax increase for property owners because there is virtually nothing to cut from the municipal side of the budget, Whitefield Selectman Frank Ober said at a hearing Thursday in Windsor.

“It’s going to be a hard sale, to me, saying you’re going to have a tax increase in Whitefield, and that’s because of the schools,” Ober said.

The towns in RSU 12 are Alna, Chelsea, Palermo, Somerville, Westport Island, Whitefield, Windsor and Wiscasset.

The new formula multiplies a town’s number of resident students by RSU 12’s average 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.

The change would be phased in over three years to prevent abrupt changes for towns and taxpayers.

When the school board presented an earlier cost-sharing proposal, towns that bring a large amount of state subsidy into the district, such as Windsor, said they should get credit for that because it reduces the amount of money RSU 12 has to raise in local taxes.

“That was the message loud and clear from folks in this room when we held the public hearing here,” said finance committee chairman Jerry Nault, a board member from Windsor. “They wanted that subsidy acknowledged as far as their contribution goes.”

If approved, the new formula could assuage Westport Island and Wiscasset, which are seeking to withdraw from the district in part because they pay more per student than the other towns.

Westport Island board member Richard DeVries said the new plan would satisfy his town’s withdrawal committee.

“If it passes in November, Westport Island will not withdraw,” DeVries said. “I’m on the withdrawal committee, and the withdrawal committee has already come to the conclusion that the recommendation we will make to the voters is not to withdraw.”

RSU 12 board Chairwoman Hilary Holm said there has been no word from Wiscasset on what it would do if the plan passes.

Ober said being in RSU 12 has saved towns money, and the new formula could keep the district together if Westport Island and Wiscasset are happy with it.

“I understand why you’re trying to do it, it makes sense,” Ober said. “These people will be happier, and maybe it’ll keep this thing going. But the reality is, there will be a tax increase (for Whitefield).”

The same formula would apply to adult education as well as expenses for pre-kindergarten through 12th grade. Some people at the Windsor hearing questioned whether that is the most appropriate way to share costs for adult education, and Nault said he is not sure, either.

At the end of the hearing, Holm asked if the proposal seemed fair.

“I haven’t got a clue,” Chelsea Selectwoman Linda Leotsakos said. “I have to think about it.”

Susan McMillan — 621-5645

smcmillan@mainetoday.com