The Loudoun County Board of Supervisors yesterday approved, 5 to 3, a budget of more than $107 million and lowered the property tax rate by 11 cents, from $1.13 per $100 of assessed value to $1.02.

The board's action means that the new tax rate, combined with a recent 12.3 percent real estate assessment increase, will push the tax bill for the owner of a $100,000 house, now valued at $112,300, to $1,145. Under the old $1.13 rate the taxes on the house would have been nearly $1,270.

The supervisors who voted for the measure, Chairman James Brownell, Frank Raflo, Steve Stockman, Andrew Bird and Frank Lambert, said the increased assessments, expected to bring in approximately $35 million in added revenue next year, will be enough to fund the growing county's needs. The budget, which is the county's first of more than $100 million, will increase county spending by a whopping 32 percent next year.

Board Vice Chairman Betty Tatum, Anne Kavanagh and Thomas Dodson voted against the budget, they said, because they believe an original motion, which called for a 10 cent decrease in the tax rate, would be necessary despite the increased real estate assessments. "This year local governments are having to deal with Gramm-Rudman cuts," Tatum said. "What if we need that money?"

Although booming development, much of it in eastern Loudoun, will give the county between $7.7 million and $8.8 million in additional funds next year, County Administrator Philip Bolen had requested a tax increase to $1.16 in his budget proposal in March.

The budget includes a $58 million school budget, slashed nearly $900,000 by the supervisors last week. Despite the cuts, school employes will receive an 11 percent salary increase with a $20,000 salary for beginning teachers, a $2,500 increase over last year.

While the board approved a 3.5 percent salary increase for county employes, it voted against a proposal that would have lengthened the employes' work week from 37 1/2 hours to 40. Bolen had requested the measure, saying the move would reduce overtime costs and improve productivity.