Fairfax County School Superintendent Daniel A. Domenech said yesterday the school system needs an additional $112 million in the next fiscal year, more than twice the increase county supervisors said they could provide without raising taxes.

"This is a statement of what our needs are at this point in time," Domenech said in an assessment of needs for the coming year. "We hear talk about education being a priority in this county. Well, the bill is due."

Domenech said the school district cannot get by with less if it is to keep pace with enrollment growth, hold down class sizes, help students meet new state achievement standards and keep teacher salaries competitive.

Domenech stressed that his announcement was not a formal budget request for the fiscal year starting July 1. He will not release his proposed budget until next month.

Supervisors, who had said that the schools should expect an increase of no more than 6 percent in county funding, were cool to Domenech's assertions. Domenech anticipates presenting a budget that will require a 13 percent to 14 percent increase in county spending.

"At the end of the day, it's possible that the Board of Supervisors could find additional money," board Chairman Katherine K. Hanley (D) said. "Can I tell you that it will get to [the increase Domenech calls for]? No. The school budget has a long way to go."

Hanley and other supervisors rejected the notion of a tax increase to pay for increased school spending. But Domenech and School Board members said they are not calling for a tax increase. They said more than $100 million of the increase is tied directly to growth and salaries--factors over which they have little or no control. Parents and community leaders also have been clear that they want the school district to ask for what it needs.

"We've gone through four years of stringing out resources. . . . We don't have any left to string out," said board budget chairman Jane K. Strauss (Dranesville), noting that the district is starting this budget without reserves. "We're running to catch up, and it's real clear that the community wants us to go forward with presenting a needs-based budget."

The supervisors issue spending guidelines annually, and in the previous two budget cycles Domenech was criticized by some School Board members, parents and community leaders for sticking too closely to the supervisors' recommendation.

Many parents also have complained that the superintendent traditionally presents his budget too late to allow for meaningful public scrutiny. Domenech said he decided to release some information now so that residents will have more time to provide feedback.

The additional $112 million in school spending that Domenech wants would represent an increase of 9 percent over the current budget. The school district also gets funding from the state and federal governments.

About $42 million of the proposed increase is directly related to enrollment growth, Domenech said. School officials anticipate that the 156,000-student district will get an additional 4,042 students next fall. They also need to cover start-up costs for a new high school in western Fairfax.

Domenech also proposed to provide all school employees with a 3 percent cost-of-living raise, compared with the 2 percent raise they got this year. He said Fairfax now lags behind Alexandria, Arlington and Montgomery in its average teacher salary.

Domenech also is proposing to expand Project Excel, a program in which struggling schools receive extra resources while facing new demands to boost their performance. The program, which now covers 20 elementary schools, would expand to four high schools and one middle school.