LYNN – It has a hilltop view of Lynn from its perch in the Highlands, and the Knowledge Is Power Program academy is starting to figure prominently in city budget calculations as elected officials start the annual process of crafting a municipal budget.”It’s been a killer for us,” Chief Financial Officer Richard Fortucci said Tuesday as he pointed out how charter school tuition costs are poised to double since 2008.Lynn’s “cherry sheet” – an expense and receipt calculation tallied up annually – lists just over $8 million in charter school tuition charges for the current spending year. State calculations for the spending year that starts July 1 average $10.5 million, depending on how the charges are calculated by the Legislature and Gov. Deval Patrick’s office.The increase is directly tied to KIPP’s expanding enrollment in its High Rock Academy, said charter school Executive Director Caleb Dolan.Opened in a parking lot trailer next to Holy Family Church in 2004, KIPP built a $21 million school two years ago in the Highlands. Its current enrollment, Dolan said, is more than 700 students. The school is adding an eleventh-grade next year.”Any increase in our funding is directly due to serving more students. We’re now on our way to being a fifth through 12th-grade and then, hopefully, kindergarten through 12th,” Dolan said.But Dolan noted that the state reimburses communities over a two-year period for tuition costs associated with a student leaving the local public school for a chartered public school. The reimbursement ultimately amounts 225 percent of the original tuition amount, said Massachusetts Charter Public School Association spokesman Dominic Slowey.”If the kids leave, so does the money. We understand that there are fixed costs (for communities) that do not move with the kids,” Slowey said.But Fortucci cited state revenue department figures to show how tuition costs associated with charter schools have expanded in the city budget over the past 12 years.Charter tuitions charges in 2003 totaled $163,000 before jumping to nearly $1 million in the following year, according to revenue department figures. By 2006, tuition charges assessed against the city totaled $3.4 million. The charges leveled for three years at $5 million beginning in 2008 before jumping to $6.6 million in 2011.”It’s a charge – a cost we have to factor in the equation to balance our budget,” Fortucci said.He noted that state local aid to Lynn schools has increased in recent years with $126 million in school aid to the city from the state this budget year with more than $7 million additional anticipated in the next budget year.Dolan pointed out that KIPP’s new Highlands school was built with privately-raised money and with rest of the project paid for with money budgeted into the charter school’s annual spending plan – money, he acknowledged, provided through charter tuition.”We’re a publicly-funded school,” he said.Thor Jourgensen can be reached at [email protected].