Agricultural land and buildings are not assessed on market value. Corn Suitability Ratings (CSRs) are used to set agricultural land value along with productivity, which includes grain prices, yields, and land owners estimated expenses. This is done county wide on a five year average based on data from USDA and Iowa State University. For example, the years used for the 2011 assessment are 2005-2009. Based on this information, the Iowa Department of Revenue informs the counties what percentage adjustments are needed for agricultural land and buildings.