Last October the Montgomery County Board of Education, under election-year fire to reduce taxpayer burdens, voted to send tuition bills to foreign diplomats and international organization employes whose children attend county schools.

The vote affected about 2,000 students whose parents, under international treaty arrangements, largely were exempt from paying taxes that support the schools.

It was a nationally unprecedented move that was expected to result in an additional $1.3 million in school operating funds, and was scheduled to become effective 10 days from today.

Tonight, after months of diplomatic protests and U.S. State Department criticism that the plan would subvert U.S. treaty obligations; the school board will consider a substitute plan that essentially abandons the original policy. It also drastically reduces the amount of money that the board expected to derive from the tuition plan.

As board member Joseph R. Barse put it, "The whole thing can become a terribly sticky wicket."

At issue in the board's October decision was a question of taxpayer equity. The Montgomery County Taxpayer's League, which was then exercising new-found political strength, pointed to the presence of diplomats' children in the school system as a prime example of government waste.

"Why should they [diplomats] be getting a free ride on the backs of local taxpayers?" asked league member Karl Schlotterbeck.

So the board voted to charge $2,258 in 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.

In addition, the board voted to send prorated bills to parents who paid some but not all of the taxes that support their children's education.

The nonresident tuition policy triggered a dispute between the board, the local diplomatic community and the State Department, which declared that the board's action would open the way for diplomatic lawsuits and produce serious repercussions for American personnel abroad.

State Department legal adviser Horace Shamwell said diplomats are exempt from paying local taxes under the Vienna Diplomatic Relations Convention of 1961. He said that tuition charges would constitute the equivalent of taxation.

"It (the board policy) could be illegal and a violation of American treaty obligations," he said.

So in recent months the school staff, acting on the legal advice of board attorney Charles Reese, have scurried to prepare a substitute plan that abandons the philosophical intent of the original policy.

"I think if we were to implement it (the original policy) we'd find the gains offset by legal expenses," said one school official.

According to the staff plan that will be presented at the board meeting tonight, parents who can prove "bonafide residence" in Montgomery will be exempt from tuition charges.

Proof of residence would include a local driver's license or verification that mail to a student's parents is addressed to a Montgomery address.

The plan would mean that diplomats and international organization employes on "A" or "g" visas who reside in Montgomery would be exempt from the tuition policy.

School officials predict that perhaps only 8 to 10 percent of the parents of the 2,000 students affected by the original policy, would still be covered under the alternative plan.

Currently about 150 nonresident students attend Montgomery County schools. Their parents pay a total of about $300,000 in tuition charges.

If the alternative plan is adopted, the figure would climb to about $500,000, but far below the $1.3 million expected under the original policy.

Board members questioned about the alternative plan said they had not yet become familiar with it.

The plan would appear to be acceptable to the local diplomatic community. "I hope it's adopted," said Alfred Scanlan, an attorney representing six Montgomery employes of international organizations.

"It will avoid the necessity of our suing them."

Just in case, Scanlan sent a legal brief to the school board several days ago outlining the class action suit he promised to file Monday if the board declined to alter or refine the nonresident tuition policy before next month.

Taxpayer league member Schlotterbeck, meanwhile, expressed dismay over the alternate plan."Probably the ideal solution would be to get the federal government to assume more of the financial burden of its treaty obligations," he said.

Board member Barse agreed. "If the issue becomes too legally entangled, that would be a good compromise."