Wash. Rev. Code § 35.43.186
A city or town ordering a local improvement upon which special assessments on property specifically benefited by the improvement are levied and collected, may provide as part of the ordinance creating the local improvement district that moneys paid or the cost of facilities constructed by a property owner in the district in satisfaction of obligations under chapter 39.92 RCW, shall be credited against assessments due from the owner of such property at the time the credit is made, if those moneys paid or facilities constructed directly defray the cost of the specified improvements under the district and if credit for such amounts is reflected in the final assessment roll confirmed for the district.
RCW 35.43.186
Severability-Prospective application-Section captions-1988 c 179: See RCW 39.92.900 and 39.92.901.