Wash. Rev. Code § 35.33.135
At a time fixed by the city's or town's ordinance or city charter, not later than the first Monday in October of each year, the chief administrative officer shall provide the city's or town's legislative body with current information on estimates of revenues from all sources as adopted in the budget for the current year, together with estimates submitted by the clerk under RCW 35.33.051. The city's or town's legislative body and the city's or town's administrative officer or his or her designated representative shall consider the city's or town's total anticipated financial requirements for the ensuing fiscal year, and the legislative body shall determine and fix by ordinance the amount to be raised by ad valorem taxes. Upon adoption of the ordinance fixing the amount of ad valorem taxes to be levied, the clerk shall certify the same to the board of county commissioners as required by RCW 84.52.020.
RCW 35.33.135