SOMERVILLE — A new cost-sharing method for Regional School Unit 12 was approved by a large margin, passing even in towns likely to pay more in taxes.

According to unofficial results from Tuesday’s election, seven of eight towns approved an amendment to the RSU reorganization plan so that each town will pay the same average cost per student. Only Somerville voted no, by 133-105.

The vote for the new method was 328-117 in Alna; 701-516 in Chelsea; 388-325 in Palermo; 379-79 in Westport Island; 652-481 in Whitefield; 579-526 in Windsor; and 1,349 to 533 in Wiscasset. The amendment also included a safety net provision to ease the transition for towns as the tax burden shifts.

Jerry Nault, a school board member from Windsor and chairman of the Finance Committee, said he was surprised to see the change approved in towns that stand to pay significantly more, specifically Palermo and Windsor.

“I think people that were familiar with it kind of came to the conclusion that this was a fair way by which costs could be allocated,” Nault said. “And hopefully fairness trumped their concerns over increased costs.”

The new cost-sharing method will apply to the 2013-14 school district budget.

An analysis prepared by the school board shows that if the new method were applied to this year’s budget, Palermo’s obligation would be 25 percent higher, Somerville’s 32 percent higher and Windsor’s 20 percent higher.

Meanwhile, Westport Island’s share would be 33 percent lower and Wiscasset’s 12 percent lower.

Alna, Chelsea and Whitefield would experience single-digit changes.

If next year’s school district budget and student populations by town remain largely similar, so will the cost allocation. But the safety net means only 25 percent of the change will apply to each town’s tax bill, so towns that owe more will not have to pay the full amount, and towns that owe less will not reap the full savings. In the second year, the safety net will be 50 percent and in the third year, 75 percent.

Since RSU 12 formed in 2009, cost-sharing has been determined by a percentage formula based on each town’s school spending in the year before consolidation. As members of School Union 133, Palermo, Somerville and Windsor kept costs low, so their tax contributions to RSU 12 are low relative to their student populations.

“The economic advantage they were enjoying was the consequence of one year of budget consideration, which may or may not have reflected what’s going on today, in any of the towns,” Nault said.

The referendum also changed cost-sharing for adult education, which will be based on each town’s percentage of the total population in RSU 12.

Susan McMillan — 621-5645
smcmillan@mainetoday.com