New commercial construction, including new apartment buildings, combined with Arlington’s typically strong residential sales, pushed the county’s 2014 real estate assessments up by 5.8 percent.

The commercial tax base, which was expected to be flat in 2013 because about one in five commercial spaces are vacant, actually rose 5.4 percent, primarily fueled by new construction and strength in apartment properties, the county said.

Residential property owners saw the value of their homes rise 5.3 percent, so that an average single-family home, condo or townhouse is worth $552,700. That will likely mean higher taxes in the coming year but it could also mean a higher price if a homeowner sells.

The County Board told its staff in November to prepare a budget without a tax rate increase; however, if a property’s assessment rises, even an unchanged tax rate will mean a higher tax bill. Arlington’s current tax rate is $1.006 per $100 of assessed value.

Real estate assessments are being mailed Wednesday, and after 11 p.m., residents can look up the assessment on their property at

Higher assessments are good news for the Arlington County government. County manager Barbara Donnellan had forecast a budget gap of as much as $25 million in the coming fiscal year, and this news will bring about $20 million more than expected into the county’s coffers, said budget director Richard Stephenson.

“We are grateful that Arlington continues to show resilience and stability, despite ongoing tensions in the larger economy,” Donnellan said in a statement. “I am pleased the budget gap is narrowed, but we still face expenditure pressures for both county and schools.”

Donnellan is scheduled to present her recommendations for the fiscal 2015 budget to the County Board in mid-February. The board spends much of the spring working on it and normally passes the budget and sets the tax rate in May or June.