Properties that are classified as residential, commercial, and industrial are to be assessed at 100% of the current market. Iowa assessors are required to develop the assessments through the use of a cost manual supplied by the Iowa Department of Revenue. Once the replacement cost new is obtained, depreciation for age and condition is applied, then any adjustment needed to reflect the current market is given. This value is added to the land and the result is to be reflective of the current market value.
The assessments for agricultural property (land and buildings) is not done at market value. It is determined using a productivity and net earning capacity formula which considers a five year, rolling average of costs, yields and commodity prices. This is done every odd year on a county-by-county basis.