Most of the staff who aren’t teachers but help keep Indianapolis Public Schools running, from principals to custodians and bus drivers, could earn bonuses of $1,250 this year and another $1,500 next year under a plan approved by the school board tonight.

The first round of bonuses will go to non-teaching staff who have worked for the district for at least 16 months. Newer staff will be eligible for bonuses next year.

But about 800 other support staff represented by the AFSCME Local 661 union, must wait for a vote on a tentative contract that includes the bonuses. AFSCME leaders did not immediately respond to a request for comment.

The bonuses would be big paydays for employees who typically earn substantially less than the teaching staff in IPS — the bonus amounts are nearly 12 percent of the average pay for workers in the union, according to IPS. But they are only a short-term commitment. The contract does not increase base pay, and workers have no guarantee they will earn a similar bonus in the future.

By agreeing to the deal, union leadership passed up an alternative offer from IPS that offered a 1.5 percent increase in pay each year for two years. Those raises offered more security, but they were substantially less up front money than the bonuses, amounting to less than half the cash for even the highest paid workers over the first two years.

The district offered big bonuses or relatively small pay raises because the financial forecast for IPS is unclear, Superintendent Lewis Ferebee said.

“We’re not able to project what our revenue will be and forecast out our ability to have higher increases in compensation over an extended period of time,” said Ferebee. “We wanted to ensure that we can get as much money into those individuals pockets as we could.”

The union’s contracts have not included base pay increases since 2010, but the bonuses mirror the deal from last year, which awarded $1,000 bonuses.

Only workers who’ve been with the district since July 1, 2014, with clean disciplinary records are eligible for bonuses this year. To earn bonuses next year, staff must have begun work at IPS before July 1, 2015.

IPS estimates that more than 2,000 staffers will be eligible for the bonuses. That includes the 870 workers the union represents, support staff and administrators such as building principals.

The deal also includes extra stipends of $500 for special education assistants, positions the district has struggled to fill in the past.

IPS estimates that the bonuses will cost the district about $4.5 million over the two-year period.

The financial picture for IPS is mixed. The district has saved money recently by cutting central office staff, Ferebee said. And it ended two recent years with budget surpluses of $4 million and $8 million.

But it ended the first half of 2015 will a deficit of $761,000. And IPS lost significant state aid in the most recent budget. Based on early estimates, the district expects to get $11 million less than last year, Ferebee said.

“IPS is providing all of this compensation at a time when we will have millions of dollars less in funding and state revenue,” he said. “We’ve made significant investment in our employees at a time when we have significantly less dollars.”