The Arlington County Board is scheduled to receive from the school board today a list of $3.4 million in possible cuts from the proposed fiscal 1982 school budget, together with an explanation of what the impact of those cuts could be.

If all the potential budget-slashing measures are adopted, there would be a reduction of 42 1/2 staff positions, and school employes would get a 6 percent raise instead of the 9 percent the school board has requested. A 1.2 percent pay hike has been proposed for other county employes.

A lower pay increase, coupled with possible elimination of the proposed increase in the school board's contribution to employe medical coverage, would account for nearly $2 million in cuts.

The possible elimination of 42 1/2 staff positions, including 20 teacher aide positions, would save $888,000, and another $429,000 could be cut in equipment, supply and contingency accounts, under the tentative cut list.

The County Board ordered the school board to provide a list establishing priorities for possible cuts by today so the proposals could be studied before the two boards meet again April 22. By law, the budget must be approved by May 1.

The school board reluctantly reviewed the list of what members called "illustrative cuts" designed to show how $3.4 million could be cut so that the County Board's share would be brought down to $43.5 million, the limit the County Board said it would be willing to contribute to the over-all $60 million proposed school budget.

Acting Superintendent J. Boyd Webb, who prepared the list after consulting with principals and staff, maintained there was no "fat or cushion" in the budget initially proposed by former superintendent Larry Cuban.

"I still feel that the budget presents a realistic need for the school system in order to continue to provide a high-quality educational program for its students and to provide for needed staff compensation," Webb said.

"Every one of these cuts will reduce the flexibility of the school system," said board member Torill B. Floyd who, with members Ann C. Broder and Evelyn Reid Syphax, voted to ask the County Board for the $46.8 million Cuban initially proposed for the county's share.

Board chairman O.U. Johansen and board member Claude M. Hilton both said the board had failed to "bite the bullet" in work sessions by identifying cuts that would have met the County Board's spending guidelines for schools.

After Hilton complained repeatedly that the board had not adequately reviewed possible cuts during its numerous work sessions, Floyd countered, "You've been quiet (on proposed cuts). You always want someone else to bite the bullet for you."