Why Do Values Change?

Why do assessed values change even though I haven't made any changes to my property?

Iowa law requires that all real property be reassessed every two years on the odd numbered years (2017 - 2019 etc). A change in the market value of a property can be from new construction or building removals, but it can also come from changes in market value that are caused by inflation, deflation (recession) or economic changes within a small neighborhood area. The assessor estimates the market value only after researching sales and completing sales ratio studies which show market trends. An analysis of local conditions as well as economic trends both in and outside the construction industry are also used in determining property assessments.
After properties have been appraised, the preliminary assessed values are analyzed to ensure that accurate and equitable values were established using the most recent selling prices.