There shall be exempt from taxation a portion of each separately assessed stock of merchandise, as that word is defined in this section, owned or held by any taxpayer on the first day of January of any year computed by first multiplying the total amount of that stock of such merchandise, as determined in accordance with RCW
84.40.020, by a percentage determined by dividing the amount of such merchandise brought into this state by the taxpayer during the preceding year for that stock by the total additions to that stock by the taxpayer during that year, and then multiplying the result of the latter computation by a percentage determined by dividing the total out-of-state shipments of such merchandise by the taxpayer during the preceding year from that stock (and regardless of whether or not any such shipments involved a sale of, or a transfer of title to, the merchandise within this state) by the total shipments of such merchandise by the taxpayer during the preceding year from that stock. As used in this section, the word "merchandise" means goods, wares, merchandise, or material which were not manufactured in this state by the taxpayer and which were acquired by him or her (in any other manner whatsoever, including manufacture by him or her outside of this state) for the purpose of sale or shipment in substantially the same form in which they were acquired by him or her within this state or were brought into this state by him or her. Breaking of packages or of bulk shipments, packaging, repackaging, labeling, or relabeling shall not be considered as a change in form within the meaning of this section. A taxpayer who has made no shipments of merchandise, either out-of-state or in-state, during the preceding year, may compute the percentage to be applied to the stock of merchandise on the basis of his or her experience from March 1st of the preceding year to the last day of February of the current year, in lieu of computing the percentage on the basis of his or her experience during the preceding year. The rule of strict construction shall not apply to this section.
All rights, title, or interest in or to any aircraft parts, equipment, furnishings, or accessories (but not engines or major structural components) which are manufactured outside of the state of Washington and are owned by purchasers of the aircraft constructed, under construction or to be constructed in the state of Washington, and are shipped into the state of Washington for installation in or use in connection with the operation of such aircraft shall be exempt from taxation prior to and during construction of such aircraft and while held in this state for periods preliminary to and during the transportation of such aircraft from the state of Washington.