Loudoun County Administrator Tim Hemstreet kicked off the county’s annual budget review process Wednesday by presenting a proposed spending plan for fiscal 2018 that funds almost all of the school system’s request and provides staffing for several new facilities while holding property tax bills steady.

The $2.5 billion budget complies with the Board of Supervisors’ demand for a plan that avoids increasing the average homeowners’ tax bills. It would boost local funding by $61 million for the school system and $27.7 million for the general county government.

Under the budget proposal, the real property tax rate would be lowered to $1.135, 1 cent less than the current rate. Coupled with rising property values, the lower rate would hold tax bills relatively constant.

“The county’s current economic situation is more favorable than last year,” Hemstreet said, pointing to growth in employment and increases in residential, commercial and industrial property values. “However, the county’s needs continue to surpass the resources available.”

For the first time in several years, the spending plan would fund nearly all of the school board’s request, falling just $3.5 million short. Last year, the supervisors’ budget deliberation process began with a shortfall of $31.4 million in funding for the school system. The year before, the gap was about $25 million.

Fully funding the school board’s request would allow the public schools to maintain current class sizes and extend full-day kindergarten to 82 percent of students. It would also increase funding for mental health services for high school students that use teams of psychologists, social workers and counselors.

The school board’s budget includes funds to increase employee salaries by an average of 2.2 percent. It provides an additional $10.3 million to further increase the competitiveness of teacher salaries, and $2.3 million to boost the pay and extend the hours of school bus drivers.

The budget request for the school system also includes funding to staff Brambleton Middle School, which is scheduled to open in the fall, and two schools opening the following year.

For the county government, the spending plan would add 189 staff positions and increase employees’ pay by an average of 3 percent. Some of those positions would be needed to staff new facilities, such as the Dulles South Multipurpose Center, Kirkpatrick Farms Fire Rescue Station, Brambleton Library and the Ashburn Sheriff’s Station.

Hemstreet said that the rapid growth of Loudoun’s population continues to increase the demand for county services. The budget would add resources to public safety agencies and social safety net services, such as substance abuse programs, domestic violence prevention and intervention, and child protective services, he said.

County Treasurer H. Roger Zurn Jr. said the growth in tax revenue generated by Loudoun’s 70 data centers is a major contributor to the improved financial outlook. Personal property taxes on computers have surpassed those on vehicles as the second-leading source of county revenue, trailing only taxes on real property, he said in an interview.

Personal property tax revenue from computers is projected to be nearly $155 million next year, an increase of 15 percent over the current fiscal year, Hemstreet said.

After Hemstreet’s presentation, Board of Supervisors Chair Phyllis J. Randall (D-At Large) said the Department of Economic Development has “done an amazing job of bringing in businesses to the county, and because of the businesses, we are looking at a better budget outlook than we have in the past.

“But the other [side] of that coin is, when you grow a county as large as we have, as fast as we have, you are going to have people come into the county who have mental health [and] substance abuse needs,” Randall said.

“We really do need to focus on some of those behavioral health issues and human services issues . . . that have not been funded at adequate levels in years past and have left funding gaps that are now almost at critical levels,” she said. “When you ask staff to do more with less . . . they get more creative [but they] also get burned out, and some of your most talented staff will leave.”

The Board of Supervisors has scheduled public hearings on the proposed budget Feb. 28 and March 2 and 4. The board will continue its deliberations in March, and it is expected to adopt the budget in early April.