About 90 commercial properties, many in the Clarendon area, will have their tax assessments reviewed after Arlington County said the value of their property jumped 50 percent or higher in the past year.

The retail businesses along Wilson Boulevard reported higher assessments that could add tens of thousands of dollars to their tax bills, an expense that many small restaurateurs would be hard-pressed to afford. The unusual change, in a year when commercial retail asssessments rose 12.4 percent on average, was first reported by the Arlnow.com blog.

Arlington County officials said Friday that it will review all commercial assessments with a 50 percent or greater increase from 2013. The review affects about 90 of the 3,300 commercial parcels in the county, and is expected to take 30 to 45 days. After the review is finished, property owners can still appeal the decision through the county Board of Equalization.

Assessments for this type of property in Arlington are based on the rents and expenses of the property and building in which the business is located, officials said.

“When there is new construction or a site plan or rezoning approval, you can see assessment increases of this magnitude,” said Michelle Cowan, Arlington’s chief financial officer. “We will look at them again ... we want to assure fair and equitable assessments for all property owners.”