The Arlington County Board yesterday adopted a budget for the next fiscal year that includes a 4-cent cut in the real estate tax rate, but most residents will pay more taxes anyway because of the rise in assessments.

The budget, which is up 6 percent over last year, gives county employes a 5 percent wage increase, and includes money to pay for operating the Metro subway system during evenings and weekends.

"It's kind of a typical, low-key Arlington budget," said Board Vice Chairman Ellen M. Bozman during a two-hour discussion of the $154 million budget. "Nothing flashy, nothing splashy, but kind of a moving forward to make some improvements."

The new rate is $1.45 for each $100 of assessed value - one of the lowest rates in the metropolitan area. Homeowners, however, will pay more taxes because assessments rose an average of 9.3 percent his year.

Bills for the first installment of this year's taxes are due Monday and are based on the old rate of $1.49. The October tax bills will reflect the new rate, which is expected to be ratified following a public hearing June 24.

For example, county budget chief Anton S. Gardner said that under the old $1.49 rate the owner of a house assessed at $58.900 (close to the county average) would pay $878 in taxes. Because of the rise in assessments the same house would next year be valued at $64,000 and its owner would pay a tax bill of $934, even though the tax rate will be slightly lower.

The budget for the year beginning July 1 contains five new positions and a few modest programs proposed by County Manager W. Vernon Ford. Close to $125 million of the money would come from county funds with the remaining $30 million provided by state and federal money.

The budget calls for spending $37.4 million for schools with another $10 million coming from state andfederal sources. Other expenditures include $58 million for county services which include police and fire protection, $13 million in payments on the county debt and $6.6 million for Metro, the largest single increase in the budget.

Gardner said that the Metro increase - up 94 percent over this year's payments - is due to previous under estimates of the cost of running the system and allocations for the expansion of the subway system to evening and Saturday hours scheduled to occur in late September.

Other expenditures include $9.8 million for public assistance and mental health programs, $14.5 million for operation of the utility fund and $2.2 million for the capital budget.

The most controversial item in the budget and one that has dominated the board's estimated 40 hours of late night and early morning budget work sessions was pay raises.

County Manager Ford had proposed giving 7 percent increases to county employes who last year received raises rainging from 2 to 5 percent. Last year the board cut the real estate tax rate by 2 cents.

Two weeks ago about 300 angry employes, many of them teachers, picketed the courthouse after the board had tentatively voted to grant only a 5 percent increase.

However, a majority of the five-member board, led by the fiscally conservative Joseph S. Wholey have said repeatedly that county employes' salaries are commensurate with other jurisdictions.

Wholey has said he favored using the $4.4 million surplus to cut the real estate tax rate and for improvements in the capital budget such as parks and bike trails. A 7 percent pay raise would have cost the county $5.2 million.

"The personal income in Arlington is going up less than in other [area] jurisdictions," Wholey said. "All across the county citizens are asking . . . local governments to give them some [tax] relief. Our teachers [in particular] rank very well in the metropolitan area." The median income in Arlington is $18,500, slightly lower than the average teacher's salary.

Board Chairman John W. Purdy and Vice Chairman Bozman said they favored granting 7 percent increases. "I don't think a 4-cent reduction in the tax rate is significant," Purdy said.

"I think our blue collar workers need 7 percent," said board member Dorothy T. Grotos. "But it's a compromise budget and I'll vote for it." Board member Walter L. Frankland joined Wholey and Grotos in supporting 5 percent raises.

Among the other additions in the budget were $219,000 for development of a hospice for terminally ill people, $200,000 for increased tax and rent relief for low-income residents, $200,000 for a litter control program, $90,000 for a transit subsidy program for low-income residents and $48,000 to expand evening hours at the country's six branch libraries.