Officials with the cash-strapped Chicago Public Schools had hoped to save money by enticing longer-tenured, higher paid teachers to bite at a retirement bonus, but too few applied.

CPS officials had offered the extra $1,500 for each year on the job as part of their contract with the Chicago Teachers Union.

But fewer than 900 teachers agreed by March 31 to commit to retire. The school system needed at least 1,500 to do so, or the retirement incentive would be pulled.

Now, those who signed up by the deadline have until the end of this month to withdraw their applications to retire, according to a letter CPS has sent them.

CPS officials were counting on saving money this budget year even with the bonuses, estimated to come to about $33,000 per teacher to anyone who retired in June. They planned to do that by delaying payment of the retirement bonuses until as late as December, well into a new budget year, when they would no longer have those longer-tenured teachers’ higher salaries, $85,000 to $100,000 each, on the payroll.

In 2017-18, “we expected to spend $63 million and realize $63 million in savings,” district spokeswoman Emily Bittner said. “In future years, the District expects the $63 million in savings to carry forward because the staffing changes will have been permanent.

“We won’t know future financial implications until we know the number of retirements.”

After the teachers contract was signed in October, only minutes before a union strike deadline, sources had told the Chicago Sun-Times that CPS might see additional savings, beyond what they’d get by having higher-paid teachers retire. The reasoning was that student enrollment has been declining for years, so it was likely they wouldn’t need to replace all of the retirees.

At the time, the sources said the savings in the budget year that begins July 1 weren’t expected to be large, given that the onetime bonuses would cost an estimated $63 million, but could jump to at least $80 million the next year.

Much of the savings would be from replacing the retirees with lower-paid newcomers. First-year CPS teachers make about $50,000 a year.

Classroom aides also were offered a retirement deal if at least 600 of them who had been on the job for 10 years or more took the offer of an additional $750 per year of service. Chicago Teachers Union Staff Coordinator Jackson Potter said just 300 signed up.

“I was surprised to hear the extent of distrust, uncertainty, disbelief among people who were interested in theory but didn’t believe CPS would honor it appropriately,” he said.

Other contractual agreements — that teachers would get a certain number of training days — were pushed aside when CPS turned those scheduled days into unpaid furlough days aimed at saving money, he said.

Folks also were wondering about what Potter described as an ethical question: “Teachers were asking whether or not the intention was to get rid of veteran teachers” and not replace them.

“Despite people being tired and fed up with the district, there still is a moral commitment to their students and buildings where they’ve taught for decades,” Potter said.