Wash. Rev. Code § 28A.150.400
State and county funds which may become due and apportionable to school districts shall be apportioned in such a manner that any apportionment factors used shall utilize data and statistics derived in the school year that such funds are paid: PROVIDED, That the superintendent of public instruction may make necessary administrative provision for the use of estimates, and corresponding adjustments to the extent necessary: PROVIDED FURTHER, That as to those revenues used in determining the amount of state funds to be apportioned to school districts pursuant to RCW 28A.150.250, any apportionment factors shall utilize data and statistics derived in an annual period established pursuant to rules and regulations promulgated by the superintendent of public instruction in cooperation with the department of revenue.
RCW 28A.150.400
Severability-1972 ex.s. c 26: "If any provision of this act, or its application to any person or circumstance is held invalid, the remainder of the act, or the application of the provision to other persons or circumstances is not affected." [ 1972 ex.s. c 26 s 4.]