ROCKPORT, Maine — Town officials claim that school district leaders largely disregarded their concerns about the formula used to calculate annual funding over the past years.

Rockport filed a lawsuit last month against Camden-based Municipal School Administrative District 28 after district officials acknowledged it had incorrectly calculated the town’s yearly education allocations for nearly a decade.

The district’s superintendent said the error was only recently discovered. However, town officials claim they’ve questioned the funding formula since 2017 without resolution.

“This was not a math error — it was a failure by the school district to understand the fundamentals of how the school district assessment formula works under state law,” town officials said in a statement released Tuesday.

MSAD 28 serves students from Rockport and Camden in grades K-8. Both towns contribute to the funding of the combined district.

However, due to the funding formula error, Rockport has overpaid for its share of the annual school budget since at least 2009.

In Maine, property taxes generate a large portion of a school district’s funding.

For at least the past decade, MSAD 28 incorrectly calculated the share it billed to towns. Instead of billing each town based on its property valuations, it calculated payments based on the percentage of students from each town.

The district claims this error was discovered when a new business manager was hired earlier this year. But Rockport officials say the school district has failed to investigate its funding allocations for at least the past three years.

“In the view of the Rockport Select Board, this repeated error should never have been made. It is the legal responsibility of the school district to properly assess the taxpayers who provide the funding for their operations and pay the significant debt service on new school construction,” according to the statement.

In 2017, Rockport’s assessor asked the district’s business manager if a change in the town’s valuation would impact its contribution to bond costs for a new middle school. The business manager said the allocation for each town was determined by the number of students it sends to the district, according to the statement.

In January 2019, the town assessor asked the school board chair and the superintendent when Rockport’s new valuation would be reflected in its funding allocations. In 2015, Rockport saw its valuation decrease and Camden saw its valuation increase in 2017.

School officials did not respond, according to Rockport officials.

When Rockport officials followed up six months later, they said the superintendent incorrectly stated in an email that the answer was “very simple” but would “not offer much satisfaction.”

“Rockport’s valuation is irrelevant in our school funding formula. … [Camden and Rockport] and the share of the budget for each town is based solely on student numbers,” according to the statement.

In its lawsuit, Rockport seeks to recover the full amount of overpayment the town has made, plus interest.

While the cumulative amount of overpayments is not yet known, for the 2019-20 school year alone, Rockport overpaid by about $450,000 due to the funding error.

The error was discovered in time to adjust the payments for the 2020-21 school year.