The letter requests that the school department carry out a detailed analysis of the cost increases to determine whether the increases are justified and why.
From the 2003-04 to 2008-09 budgets, school operating expenses have increased from $26.9 million to $37.7 million - an increase of $10.8 million, or 40 percent, according to the letter, written by commission budget committee member Don Miller.
"This works out to an average of over $2.2 million per year in each and every year, or an increase of 8.1 percent per year," he said.
School Director Wayne Honeycutt said his office has already begun to work on a report that will provide as much information as possible.
Reasons for increases in operating expenses are varied and include such things as unfunded state and federal mandates and grants that must be matched, Honeycutt said. The school department has also increased resources in targeted areas to meet identified deficiencies, he said.
According to Miller, the operating budget increases were accompanied by an increase in staff of about 163 teachers and assistants. At the same time, there was only a small increase in student population, he said.
"The school operating budget is by far and away the single largest expense for the county," Miller said. "It affects both the property tax rate and the funds we have available to carry out other county functions such as public safety, roads, etc."
Over the past five years, property taxes going to school operating expenses have increased from $5.5 million to $10.2 million, an increase of 85 percent.
School board Chairman Scott Newman said he was eager to see the school officials' report.
"If county commission wants us to provide an explanation for the increase in costs, we should be able to provide that information," Newman said.
Newman said he would like to see information that ties specific expenditures to specific system-wide educational goals, such as hiring more math teachers to improve scores in math.
School board member Gary Ubben, a professor of education at the University of Tennessee, said it might be difficult to make such specific line item correlations between educational needs and operating expenses.
Another way to look at the budget is to compare Loudon's school expenses per child with other counties in the state, he said.
"We still are spending significantly less than the state average," Ubben said.