Property values can change for many reasons. The most obvious are changes to the property itself, for example, an addition, garage, swimming pool or other improvements, or if the property is destroyed by flood or fire.
Additionally, property values change as a result of what other similar properties are selling for. When sale prices indicate new trends then the assessments need to reflect those changes. Buyers and Sellers dictate market value by their transactions in the marketplace. It is important to note that the assessor does not create this value. The assessor simply has the legal responsibility to study those transactions and appraise your property accordingly.