BANGOR — The opening of Maine’s first online charter school, set for next week, is rekindling tensions with public school officials over the financial repercussions for their districts and the competition for students.

Sparking the latest concerns were bills sent to local school districts by the virtual school, Maine Connections Academy, which some superintendents said came as a surprise over the summer. The bills indicate how many students from their district were enrolled in the new school and how much they would have to pay the school as a result.

Like all charter schools in Maine, the virtual school is funded through the home school districts of the students who enroll. School districts with students who attend a charter school pay the charter school an allocation, which includes state and local funding, for each student.

The difference with the online charter school is that it’s enrolling students from across the state. So while brick-and-mortar charter schools affect only the districts in their regions, many districts are now losing students to a charter school without any boundaries.

This has struck a nerve with some superintendents.

“At a time when Maine is struggling with poverty, schools are making drastic cuts everywhere, now we have this virtual school on top of it,” said Tim Doak, superintendent of School Administrative District 27, which serves Fort Kent.

Two students from the Fort Kent area will attend Maine Connections Academy. One student had been home-schooled, Doak said, so that student wasn’t counted in the district and therefore unaccounted for when the state calculated its cost-sharing contribution to the district. Still, the district now must pay for that student to attend the virtual charter school.

The cost of educating a student in the Fort Kent area is about $7,000, so the district’s bill from the charter school comes out to $14,000 — all of which must be paid this year — according to Doak.

“Right now, we have no way to prepare for this,” he said. “Should we have a line [in our budget] that’s $25,000 for virtual charter schools just to be safe? I don’t know.”

The cost per pupil that districts must pay charter schools varies depending on geography, but the average in Maine is $6,509 for students in pre-kindergarten through eighth grade and $6,967 for high school students, according to the Maine Department of Education.

School districts get additional subsidies from the state and federal government if their students qualify for special education or are economically disadvantaged, and if those students decide to attend a charter school, the funds go with them.

By mid-July, Maine Connections Academy had received 247 intent-to-enroll letters, four more than the minimum required by the Maine Charter Commission for the school to open. If the cost per student is about $6,700, that means the school will receive about $1.7 million, though that does not account for funds for special education or economically disadvantaged students.

The school maintains an office in South Portland where its teachers and principal will work. The teachers will conduct lessons, assign homework and grade assessments online and are available to speak with students by phone, board members have said.

The virtual school has a contract with Connections Academy, a company that supported 25 virtual charter schools in 23 states in the 2013-2014 school year, according to its website.

Connections Academy is owned by Pearson PLC, a London-based publicly traded publishing company that is responsible for many standardized tests and textbooks used in the U.S.

Maine Connections Academy officials declined to give the breakdown of which school districts or towns their enrolled students are coming from. Classes start on Tuesday.

A problem with the money-following-student system is that the majority of costs associated with running a school are not per pupil. A district that now has five high school students attending the new charter school, for example, can’t eliminate a teacher at its high school. Its heating costs haven’t dropped and it still fields the same number of sports teams. It costs the same to run its bus, even though five fewer students now ride it. But it must now operate its school with less money.

The money districts send to charter schools comes back to the districts eventually. The amount a district gets from the state and locally for the current school year is based on enrollment numbers from the previous year. When the students are counted this year to determine how much the district will get next year, the students who enroll in the virtual charter school will be counted as part of the school district.

The issue for superintendents is that they cannot predict how many students each year will leave for charter schools, taking their funds with them.

Districts, however, do not receive funds from the state for home-schooled students, so students who switch from home-schooling to attending a charter school represent a new upfront cost for school districts. However, they also will now be counted in the districts’ enrollment count, which will determine next year’s state and local subsidy.

Regional School Unit 29, which serves Houlton, has five students attending the virtual charter school, Superintendent Mike Hammer said. Their bill to the new school is just over $41,000.

In Caribou, where four students will attend the new charter school, Superintendent Susan White said she is looking at a bill of about $27,000.

Five students from Portland Public Schools will attend the virtual charter, though a spokesperson said they could not give the exact cost at this time. In Portland, the cost per pupil is $6,857 for students in pre-kindergarten through eighth grade and $7,158 for high schoolers, according to the Department of Education.

One line on the bill to the charter school that has irked some superintendents is the 3 percent that goes to the Augusta-based Maine Charter Commission.

Those funds are used by the seven commission members to carry out authorizing responsibilities, Bob Kautz, the commission’s executive director, said.

“That includes everything for the receipt of applications, the granting of the charter and, most importantly, the monitoring of the charter school’s performance,” he said.

One percent of the bill can be retained by the school districts for clerical costs.

Schools also face another challenge that increases the level of competition with charter schools: declining student populations.

In Maine, the number of students enrolled in public schools goes down by hundreds every year. During the 2006-2007 school year there were 199,567; last year there were 184,367, according to the Department of Education.

Few districts know this better than Regional School Unit 54, which serves Skowhegan and the surrounding communities. It will send $975,000 to charter schools this year, Superintendent Brent Colbry said.

But the district anticipated the loss of about 100 students because it has experience sending students to charter schools: Two years ago, two charter schools opened near Skowhegan, the Cornville Regional Charter School and the Maine Academy of Natural Sciences.

According to the most recent count, seven RSU 54 students are enrolled at the virtual charter school, 21 are enrolled at the Maine Academy of Natural Sciences and 75 are enrolled at the Cornville Regional Charter School.

Colbry has been an advocate of passing a law that would treat charter schools as their own school district, which means they would be funded by the state instead of by the individual school districts that are sending students.

“We’re hoping it will come back up again,” he said Monday. “With the advent of the virtual charters, which affects more districts, it’s more likely that that conversation will be broader.”

Doak, the superintendent in Fort Kent, supports that idea. He said he’s not against students having the choice to attend the charter school, but said getting a bill from the virtual charter schools has made him think a little differently about his district.

He said, “it makes you think, how do we do things differently to make sure they’re being served, to not lose them [to the charter school]?”