A clearer -- and more ominous -- picture emerged Monday of school districts' struggles to balance their budgets in preparation for a potential $4.8-billion state funding shortfall.

Districts around the state met two deadlines Monday: They were required to notify employees of possible layoffs and they had to report their financial data to county offices of education.

The California Department of Education estimated that nearly 20,000 employees received early termination notices, with at least one district -- Placentia Yorba-Linda Unified -- offering a $1,000 bonus to employees who retire or resign by April 1. At least 14 Los Angeles-area school districts reported that they might not be able to avoid running a deficit over the next two years.

"We've never had that many" with potential deficits, said Ken Shelton, assistant superintendent for business services for the Los Angeles County Office of Education. "While some districts may have fiscal challenges irrespective of the governor's budget, certainly the current budget proposal exacerbates the problem."

In recent weeks, school boards have moved to increase class sizes in some primary grades and some have even voted to close schools. Conejo Valley Unified in Ventura County is expected to consider closing two campuses today.

Educators have been preparing to cut costs since Gov. Arnold Schwarzenegger announced his budget, which proposes $4.8 billion in education cuts this year and next. It's the biggest education reduction in memory, school officials say.

Los Angeles Unified, the largest district in the state, is facing a projected $460-million deficit next year. Because of the financial uncertainty, the Board of Education voted to submit a "qualified" interim financial report to the county, which means that the district may not be able to meet its obligations over the next two years.

L.A. Unified decided not to issue layoff notices to any permanent teachers, guaranteeing that they will return next year.

"We gave it a lot of thought and decided, 'Why worry them unnecessarily?' " said Roger Buschmann, the district's chief human resources officer.

But the district could lay off its nearly 6,500 probationary teachers without early notices and it could also decide not to replace about 2,000 teachers for the upcoming year, Buschmann said.

The probationary teachers and retirees represent about a quarter of the district's teaching staff, said Buschmann, who quickly added that the scenario was unlikely.

"We won't be doing anything that drastic," he said.

It's unclear how much money in teachers' salaries the district would save with those moves.

A new, credentialed teacher costs the district about $66,000 annually in salary and benefits.

Although no L.A. Unified teachers were notified, about 3,000 administrators and senior management contract employees, including Buschmann, were warned that they may not return next year.

The teachers union will fight for probationary teachers, said Joshua Pechthalt, a teachers union vice president, who added that district cannot afford to lose any employees.

"We're not happy administrators are getting noticed," he said. "We're concerned overall."

The district has also studied increasing class sizes in kindergarten through third grade from 20 students per teacher to 23, which could save about $92 million, Buschmann said. Because the 20-1 ratio is a state law, changing it would require a waiver from the state and the board hasn't considered the move.

But the 6,800-student Whittier City School District board has already moved to boost class size, voting to drop classroom limits for third-graders.

The move will save Whittier about $110,000, district officials said.