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King County Department of Assessments

Setting values, serving the community, and promoting fairness and equity.

Department of Assessments

201 South Jackson Street, Room 708
Seattle, WA 98104

Office Hours:
Mon - Fri
8:30 a.m. to 4:30 p.m.

TEL: 206-296-7300
FAX: 206-296-5107
TTY: 206-296-7888

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Glossary of terms for commercial parcels

That use which will generate the highest net return to the property over a reasonable period of time.  According to the United States Supreme Court (1894) :"The value of property results from the use to which it is put and varies with the profitableness of that use, present and prospective, actual and anticipated.  There is no pecuniary value outside of that which results from such use."  (Cleveland, C. C. and St. Louis Ry., Co v Backus 154 U.S. 445 (1894) 

Washington law requires the Assessor to take cognizance of highest and best use in the establishment of true and fair value.

"Unless specifically provided otherwise by statute, all property shall be valued on the basis of its highest and best use for assessment purposes. Highest and best use is the most profitable, likely use to which a property can be put. It is the use, which will yield the highest return on the owner's investment. Any reasonable use to which the property may be put may be taken into consideration and if it is peculiarly adapted to some particular use, that fact may be taken into consideration. Uses that are within the realm of possibility, but not reasonably probable of occurrence, shall not be considered in valuing property at its highest and best use."  WAC 458-07-30 (3)