Correction: An earlier version of this article incorrectly said that the Arlington County Board did not insert language into its budget guidance document to say funding should support “excellence” in the schools. The word was inserted. The article has been updated.

More than six months before the start of the next budget year, Arlington County forecasts a “difficult but manageable” budget, with no plans for tax rate increases but some trims in spending to cover an expected gap of $20 to $25 million in fiscal year 2015.

County officials expect to address that shortage with tactics including a hiring slowdown, a tighter rein on employee compensation and a request for county departments to make budget cuts of 1 percent, added Michelle Cowan, Arlington’s director of management and finance.

This is the sixth consecutive year that Arlington is starting its budget cycle with an expected shortfall of funds, but as County Board members Jay Fisette and Chris Zimmerman noted in a Tuesday night meeting, “it almost always gets better.”

Real estate assessments are not finalized until the end of year, and both state and federal government spending, which contribute to county revenues, have not yet been set. But this is the time of year that the board gives the manager its direction on how to start building a budget, which she typically presents in February.

County Manager Barbara Donnellan and her staff said they expect the real estate tax base to rise 2.6 percent, on the strength of residential assessments going up an average 5.5 percent. Commercial property, which makes up half of Arlington’s tax base, are expected to have flat or declining assessments, which means lower tax revenues.

Rising costs include employee compensation, which accounts for 56 percent of the county’s general operating fund; new facilities such as a combined new homeless services center and county office space and the Long Bridge Park aquatics center; and a broadband fiber-optic network to be used by county government and emergency services workers.

Arlington spends more than 45 percent of its operating fund on schools, and officials expect schools will receive $425.1 million in ongoing funding, an increase of $12.5 million, or 3 percent.

Several residents Tuesday night asked the County Board to put more money into the schools, with some complaining about “half-day Wednesdays,” when students are dismissed early.

Zimmerman, who is resigning his seat in two months after 18 years on the County Board, said that throughout the years, the board has demonstrated its commitment to schools, and he suggested the speakers had come on “a fool’s errand.”

“No matter how much money Arlington County provides, the Arlington School Board makes those decisions,” he said. “They get a budget and, just like us, they make choices.”

Board member Libby Garvey cast the sole vote against the board’s guidance document.

The board told Donnellan to develop a budget based on existing tax rates, continue to invest county funds into public schools, affordable housing, environmental issues and the social safety net. The public can attend a joint county and schools forum Dec. 11 at 6 the Washington-Lee High School cafeteria to learn more.

While the county plans for the next budget year, officials also formally closed out last year’s budget, finding stronger-than-expected tax revenues. That enabled the county to plan to boost its payment to schools by $4 million for enrollment growth, bringing it more than $23 million unallocated new resources this year; increase the economic stabilization fund to $8 million; set aside $3.3 million for pay hikes for county employees; shore up the affordable housing initiatives by $4.4 million; and add $1.7 million for the budget of Artisphere in Rosslyn this year and next.