Taxpayers in dozens of Long Island school districts have been footing the bill for a computer system that can help rig elections to pass school budgets.

Bold Systems LLC, based in Bellport, LI, sells software that lets school districts track votes in real time on Election Day and identify which parents, district employees and 18-year-old students have not yet voted. The districts, it says, can then generate “call lists” to urge those voters — who are most likely to support a budget increase — to get to the polls.

But under state law, this is illegal “electioneering.”

‘FIXED’: Bold Systems LLC touts its software’s ability to swing an election, which dozens of Long Island school districts have bought into.

School districts can’t spend money to steer an election. They can urge citizens to vote, but are forbidden to call “a selective list” of cherry-picked voters.

School districts upstate and in Long Island hold yearly elections — the next set for May 21 — in which voters approve or reject proposed budgets.

Districts need more than 50 percent yes votes to pass a budget, or 60 percent if the budget exceeds a state tax-levy cap.

In most districts, elections can be close, with retirees on fixed incomes and homeowners without kids in school more likely to vote down big budget hikes.

Yet many of those budgets have passed in the past few years — including increases of about 7 percent in Sayville and West Islip.

“Nothing empowers you to get out the YES votes you need like the EMS Election Management System from Bold Systems,” the company claims on its Web site.

“If your budget votes are too close to call, EMS can provide the edge you need.”

The company says 110 New York school districts use its software.

The basic system simply computerizes the voter rolls. But the upgrades Bold has sold since 2006 “enable you to compile lists of parents, in-district staff and eligible students.”

Lists can even be segmented into key groups (such as PTA members, families with kids in athletics, or by school) to help get out the votes or conduct registration drives.

Robert Vomastek, Bold Systems’ inventor and former owner, explained: “As each voter signs in, their name is automatically removed from the call list. They can run the call list four or five times during an election.”

Asked why districts would target parents and staff, Vomastek said, “They want a higher turnout from that demographic, obviously.”

A parent who blew the whistle on the system is appalled.

“You don’t need a Ph.D. in political science to understand that this service is an unethical manipulation of the electoral process,” said Noel Feustel, a dad in the Bayport-Blue Point school district.

Through a Freedom of Information Act request, Feustel learned that 35 school districts in eastern Suffolk County have each paid up to $22,700 a year, depending on the number of registered voters, for Bold Systems — and 12 pay $2,600 extra for an upgraded version and add-on features that include categorizing voters.

The districts buy Bold at prices negotiated by Boards of Cooperative Educational Services (BOCES). Goods and services bought through BOCES are partly reimbursed with state taxpayer funds.

A day after The Post called Gary Bixhorn, chief operating officer of Eastern Suffolk BOCES, he ordered Bold to yank its Web site.

Bixhorn also said he would “disable” Bold features that track selected voters because they can be used “in a manner that violates the spirit and letter of the law.”

Several Suffolk district superintendents said they never used the software for prohibited purposes, just to tally votes.

Yet Nassau BOCES, which covers 56 school districts, touts Bold on its Web site, saying “a variety of useful reports can be generated on Election Day, such as up-to-the-minute reporting of who has voted, call lists of parents and staff who have not yet turned out to vote . . . and poll lists on the spot for poll watchers.”

Thomas Rogers, district superintendent of Nassau BOCES, told The Post he will also disable such features.

“These actions are long overdue,” said Bill Milligan, a Bayport-Blue Point school-board trustee. “I was stunned by the vendor’s marketing tactics and by BOCES’ failure to fully vet the product.”