Despite months of protests from both foreign diplomats and the U.S. State Department, the Montgomery County Board of Education stood firm last night in its resolve to send tuition bills to ambassadors and other foreign diplomatic personnel whose children attend county schools.

The board 4-to-2 vote affirming a decision made in October, affects about 2,000 students whose parents, under international treaty arrangements, are largely exempt from paying taxes to support the schools.

The tuition move, to go into effect July 1, is expected to bring in an additional $1.3 million in school operating funds.

But a lawsuit challenging the legality of charging tuition is expected to be filed first. Shortly after last night's vote, Alfred Scanlan, an attorney representing six employes of international organizations, said he will file a class action suit against the board Monday in Circuit Court.

"I really thought they'd come to their senses," Scanlan said, referring to the school board, "but I guess we'll have to meet in court."

Board members were under considerable pressure to revise the tuition plan. Nevertheless, they rejected a compromise that would have exempted diplomatic families with "A" or "G" visas and drastically reduced the amount of money taken in from new tuition payments.

In addition to protests from foreign diplomats, the State Department had warned that the tuition plan would open the way for lawsuits, subvert U.S. treaty obligations and produce serious repercussions for American personnel abroad.

But the board found the plan worth the risk.

"I think it's time to take this thing to court," said board member Daryl Shaw. "Why should we be paying a load the federal government should be carrying"

The board was unanimous in voting to petition the federal government for financial aid for the education of diplomats' children.

Board member Joseph Barse declared: "No matter how much pressure from the legal arguments, I'm still not convinced that county taxpayers are getting treated fairly," Still, Barse abstained from voting on the plan, favoring postponement until Jan. 1 for more study.

Voting to support the plan were board President Marian Greenblatt and members Carol Wallace, Eleanor Zappone and Shaw. Blair Ewing and Elizabeth Spencer voted for the substitute plan.

Interim School Superintendent Edward J. Andrews recommended against the plan, arguing that the board's legal standing was unsound.

One of the problems that State Department legal experts have warned of is that diplomats in foreign countries are exempt from paying local taxes. The lawyers argue that tuition charges would be the equivalent of taxation.

The board will charge $2,258 in annual tuition for elementary school pupils whose parents pay neither property taxes nor state income taxes; $2,419 for secondary school students, and $5,409 for handicapped students in special education classes.

The board will also send prorated bills to parents who pay some but not all of the taxes that support their children education.