Adopting a precedent followed by president tax-cutters since the Eisenhower administration, the Reagan budget proposes to reduce by 45 percent the impact aid to education program, a major source of funds for Washington area schools.

The program was established in 1950 to help local school districts offset the presence of large number of students whose parents worked at non-taxpaying federal installations. But the Reagan message said, "It is no longer feasible to provide substantial support . . . solely on the basis of the residence pattern of federal employes."

Last year the Carter administration proposed a similar cut that would have cost Fairfax County $9.9 million and Prince George's County $6 million, but Congress restored about two-thirds of the money.

Area members of Congress and school systems began to crank up their annual counterattack last night Northern Virginia's new Republican congressmen, Stanford E. Parris and Frank R. Wolf, both staunch Reagan supporters, were prepared to break ranks with the administration and fight for restoration of the funds.

"I have to represent my district," said Parris, "so I've got some parochial objections to the proposal."

"I'll have to oppose that part" of the president's budget message, Wolf said.

James W. Maza, counsel to Impacted Aid Superintendents, predicted the program would face its most severe test this year. "What is new is the mood of the nation and the Congress," he said.

The reduction from $850 million this year to $438 million from the fiscal year beginning Oct. 1 would be achieved by eliminating payments for children whose parents pay state and local taxes. Only school districts where at least 20 percent of the children's parents both work and live on federal property (primarily Indian reservations and a few military bases) will be entitled to benefits.