Wash. Rev. Code § 84.26.090
(1) Except as provided in subsection (3) of this section, whenever property classified and valued as eligible historic property under RCW 84.26.070 becomes disqualified for the valuation, there shall be added to the tax an additional tax equal to:
(3) The additional tax, interest, and penalty shall not be imposed if the disqualification resulted solely from:
[ 1986 c 221 s 7; 1985 c 449 s 9.]