Oregon Revised Statutes Revenue and Taxation § 308.275

(1) The Department of Revenue shall prescribe a base in terms of the construction costs of a specified year for the computation of reproduction costs.

(2) If any county assessor uses reproduction costs as one of the means of determining the assessed value of real or personal property, the reproduction costs shall be computed on the basis of the construction costs of the year so specified by the Department of Revenue.

(3) If any county assessor uses the prices and costs prevailing in any year as a basis for determining assessed values for any classes of property, the prices and costs for the same year shall be applied uniformly in the assessment of all property of the same class in the county.