Even before releasing next year’s proposed budget, CPS officials announced minimal details Thursday on plans to lay off 550 teachers and another 600 employees, such as clerical support staff and teaching assistants.

CEO Barbara Byrd-Bennett said the cuts are directly related to projected declines in enrollment at many schools, although those projections have not been released. This year principals and local school councils (LSCs) were responsible for proposing their own cuts – which were then approved by CPS — based on the district’s new per-pupil budgeting system. (Read a CPS fact sheet on the cuts.)

“It is difficult for schools that have sustained substantial enrollment decreases to avoid impact,” Byrd-Bennett said during a conference call with reporters. Still, she added, “this is the lowest number of impacts in the last five years.”

The district did not provide any information on which schools or job categories will be affected, or a racial breakdown of laid-off employees. It was unclear when that information would be provided, as not all teachers themselves had been officially notified. The district’s talent chief, Alicia Winckler, said principals were calling affected staff Thursday afternoon.

In a statement, Chicago Teachers Union (CTU) President Karen Lewis called the layoffs “yet another brutal attack on public education in Chicago.”

“In a little over a year, CPS student-based budgeting has led to the removal of close to 5,000 teachers, teacher assistants, librarians, paraprofessionals and school-related personnel, technology coordinators and instructional aides from classrooms as severe cuts cause principals to make the difficult decisions that the district cannot,” Lewis said in the statement.

Although the district did not provide any information on the schools that would lose employees, Winckler noted that 171 schools would not lose a single worker. She said only one-third of affected schools would lay off teachers; the remainder would be losing non-teaching personnel, ranging from clerks to security guards.

The layoffs come two months after CPS announced a budget miracle that would allow the district to claim an additional $70 million toward next year’s budget. Through an unusual accounting maneuver, CPS says it plans to borrow two months’ worth of property tax revenue from the 2015-16 school year, and start using it a year early. Board of Education president David Vitale – a banker – has defended the accounting gimmick, saying it would help CPS avoid massive layoffs.

Thursday’s layoffs don’t include about 60 teachers whose jobs are on the line because of plans announced earlier this year to turnaround Gresham, Dvorak and McNair elementary schools. As part of the turnaround process, CPS hands over management duties to the non-profit teacher training program Academy for Urban School Leadership, which can rehire some of the laid-off staff.

Byrd-Bennett bristled at the use of the word “layoffs” to describe what would happen to the employees, explaining that CPS expects to rehire many of them in the coming months to fill vacancies opened up by retirements, resignations, turnover and new positions created at schools with higher enrollment.

At the same time 550 teachers are getting the pink slip, CPS officials said that another 1,780 teaching positions will be vacant by the end of this year. Last year, CPS rehired 68 percent of the same teachers it had laid off, including a majority of teachers laid off from closed schools, district officials said.