Assessment of real property, and of personal property that is entered on the property roll, is a continuing process. Land and improvements on the land, such as buildings, are assessed in categories (§63-109, I.C.). All property is to be assessed uniformly throughout the state at its market value for assessment purposes (§§63-205 and 63 to 208, I.C.).

Plat Book

The assessor is required to have an accurate and complete plat book of land in the county, with ownership records kept up-to-date (§63-209, I.C.). Some counties do this by contractual arrangement with the local land title office, which furnishes photostat copies of all changes in ownership. Others have deputies in charge of the plats who follow all property transfers and make the necessary changes in the plat books and other assessment records.

Tax Districts Alterations/Creations

Legal descriptions of new and altered taxing districts and maps of new districts and of altered portions of existing districts must be filed with the County Assessor, the County Recorder and the State Tax Commission within 30 days after the change is effected (§63-215, I.C.).

Land Valuation

Land valuation is basic in real property appraisal for tax purposes. Periodic revaluation of all property is carried out under rules promulgated by the state tax commission. There is constant up-dating of values of lots and lands that have changed in use since the last complete revaluation with an actual sampling of sales are used in estimating current land values (§§63-203; 63 to 205 and 63 to 601, I.C.).

The Assessor is to carry out a continuing program of valuation of all properties pursuant to rules prescribed by the state tax commission, to ensure that all properties are appraised at current market value for assessment purposes (§63-314, I.C.). In order to promote uniform assessment of property, taxable property must be appraised or indexed annually (§63-314, I.C.). To achieve this, at least 20% of the property in the county must be included in each year's appraisal resulting in a complete appraisal of all property every five years. The results of the annual 20 percent appraisal must be used to index all property not actually appraised to reflect current market values (§63-314, I.C.).

Appraisal Records

The County Assessor must maintain records showing when each parcel or item of property was last appraised (§63-314, I.C.). The Board of County Commissioners of each county is to furnish the assessor with such additional funds and personnel as may be required to carry out the valuation program and may levy a tax not to exceed four hundredths percent of market value for assessment purposes (0.04%) to pay the costs (§63-314, I.C.).

State Tax Commission Rules

The State Tax Commission prepares and distributes to each county assessor rules prescribing the manner in which market value for assessment purposes is to be determined for tax purposes (§63-208, I.C.). The rules require each assessor to find market value for assessment purposes of all property within his/her county according to recognized appraisal methods and techniques as set by the commission, provided that the actual and functional use must be a major consideration when determining market valuation for assessment purposes (§63-208, I.C.).

To maximize uniformity and equity in assessment, the rules require, to the extent practicable, the use of reproduction or replacement cost less depreciation as opposed to historic cost less depreciation whenever cost is considered as a single one of the several factors in establishing market value of depreciable property (§63-208, I.C.). State law (§63-205, I.C.) requires that all property subject to assessment shall be assessed for taxation.

Property Assessment Roll

The property assessment roll must be completed and delivered to the Clerk of the Board of County Commissioners on or before the fourth Monday of June (§63-310, I.C.). The clerk must transmit it to the Board of County Commissioners for equalization.