The county assessor is authorized to require property owners to submit pertinent data respecting the cost and characteristics of any improvements on their property (RCW 84.41.041). When requiring owners to report costs associated with new construction, the assessor shall use forms prescribed or approved by the department of revenue, which forms shall require the total investment in the improvements as of the new construction assessment date, the percentage of completion of the major components of the improvements, and the estimated total cost of the project.

The reporting forms may be sent to the owners of any property upon which a building permit has been issued prior to the new construction assessment date.

The owner shall return the reporting form to the assessor, properly filled out, within thirty days of receipt.