Wash. Rev. Code § 86.09.493
On or before the fifteenth day of January in each year the secretary must deliver the assessment roll or the respective segregations thereof to the county treasurer of each respective county in which the lands described are located, with a statement of the amounts and/or percentages of the collections on said roll which shall be apportioned to the respective district funds, and said assessments shall become due and payable at the time or times general taxes accrue payable.
One-half of all assessments on said roll shall become delinquent on the first day of June following the filing of the roll unless said one-half is paid on or before the thirty-first day of May of said year, and the remaining one-half shall become delinquent on the first day of December following, unless said one-half is paid on or before the thirtieth day of November. All delinquent assessments shall bear interest at the rate of ten percent per annum from the date of delinquency until paid.
Within twenty days after the filing of the assessment roll as aforesaid the respective county treasurers shall each publish a notice in a newspaper published in their respective counties in which any portion of the district may lie, that said assessments are due and payable at the office of the county treasurer of the county in which said land is located and will become delinquent unless paid as herein provided. Said notice shall state the dates of delinquency as fixed in this chapter and the rate of interest charged thereon and shall be published once a week for four successive weeks and shall be posted within said period of twenty days in some public place in said district in each county in which any portion of the district is situated.
Upon receiving the assessment roll, the county treasurer shall prepare therefrom an assessment book in which shall be written the description of the land as it appears in the assessment roll, the name of the owner or owners where known, and if assessed to the unknown owners, then the word "unknown", and the total assessment levied against each tract of land. Proper space shall be left in said book for the entry therein of all subsequent proceedings relating to the payment and collection of said assessments.
Upon payment of any assessment the county treasurer must enter the date of said payment in said assessment book opposite the description of the land and the name of the person paying, and give a receipt to such person specifying the amount of the assessment and the amount paid with the description of the property assessed.
It shall be the duty of the county treasurer of the county in which any land in the district is located to furnish upon request of the owner, or any person interested, a statement showing any and all assessments levied as shown by the assessment roll in his or her office upon land described in such request, and all statements of general taxes covering any land in the district shall be accompanied by a statement showing the condition of district assessments against such lands: PROVIDED, That the failure of the county treasurer to render any statement herein required of him or her shall not render invalid any assessments made by any district or proceedings had for the enforcement and collection of district assessments pursuant to this chapter.
RCW 86.09.493