Seldom does the assessed value of a property accurately reflect the actual market value. The assessment information is the product provided to local governments and other taxing authorities containing all of the information on the individual assessments, including classification and value, found within that jurisdiction. Assessment staff rarely visit a property. They rely on information often found in property files at municipalities - building permits being the primary document - to stay up to date on improvements to a property that may impact value. Otherwise assessments usually follow the trend of what's happening broadly in the local market. For an accurate valuation, contact an appraiser, who will look at recent sales and adjust for differences between your property and them (i.e. single vs double garage, number of bedrooms). Even more accurate is a detailed evaluation by a Realtor, called a Comparative Market Analysis (CMA), which will factor in current listings of similar properties. Sales reflect what has happened in the market, a CMA reflects what's happening.