Your local Appraisal District examines properties according to their physical characteristics, like size, construction type, location, and use. The district may look at a property yearly or at least once every three years.Generally, the appraised value derives from a property’s fair market value. This figure represents what a property would sell for on the open market when the buyers or sellers are not under duress. Appraisers calculate this number by looking at sales data for similar properties in the area. Real estate professionals call this looking at comparables or comps. Commercial property tax values do not always fit neatly into analyses of comparable transactions. For example, income generated by productive lands, like agricultural land, guides valuation instead of market value for the land. In other situations, a commercial property may not have anything comparable to it in the area.