Important Dates Relating to Property Assessment and Taxation January 1 Property (other than new construction and mobile homes being assessed for the first time in this state) is subject to assessment and taxation. (RCW 84.36.005, 84.40.020) Assessor to mail personal property reporting forms no later than this date. (RCW 84.40.040) January 15 Assessor certifies and delivers tax rolls to county treasurer (RCW 84.52.080) January-December Assessor may accept claims for senior/disabled exemptions for taxes payable the following year. (RCW 84.36.385) January 15-February 15 No revaluation notices may be mailed. (RCW 84.40.045) February 15 County treasurer begins collecting current year taxes. Tax bills sent on or after February 14. (RCW 84.56.010) March 1 Boundaries to be established for taxing districts in order to collect taxes the following year (with certain exceptions). (RCW 84.09.030) Assessor to submit revaluation plan to Department of Revenue prior to beginning a new revaluation cycle. (RCW 84.41.041, WAC 458-12-335) March 31 Boundaries of newly incorporated cities to be established. (RCW 84.09.030) April 1 Senior/disabled tax deferral applications are due. (RCW 84.38.040) April 30 First half property taxes must be paid. (RCW 84.56.020) Taxpayers must report personal property owned as of January 1. (RCW 84.40.040) May 1 Applications for farm and agricultural current use classification deemed to have been approved if not denied by this date. (RCW 84.34.035) May 31 Assessor must have completed listing and placing valuations on all property except new construction. (RCW 84.40.040) June 1 Boundaries of newly formed districts that are coterminous with existing districts to be established by this date. (RCW 84.09.030 Penalty of 3% assessed on delinquent current year taxes on this date. (RCW 84.56.020) July 1 Valuation appeals must be filed with the county Board of Equalization or within 30 days of mailing of assessment notice, whichever is later. (RCW 84.40.038) July 15 Assessor certifies assessment rolls to the county Board of Equalization. (RCW 84.40.320) July 15 The county Board of Equalization convenes. (RCW 84.48.010) July 31 Valuation date for new construction and mobile homes subject to their first assessment in this state. (RCW 36.21.080-090) August 31 Department of Revenue provides Assessor a list of property exempt by use in the county. (RCW 84.36.385) Assessor to complete listing and valuation of new construction and new mobile homes. (RCW 36.21.080-090, RCW 84.40.040) September (third Monday) Department of Revenue certifies final county ratio to Assessor after this date. (RCW 84.48.075) September - October Department of Revenue certifies equalized assessed values of centrally assessed (utility and transportation) properties to the Assessor. (RCW 84.12.370) October - Assessor supplies Department of Revenue with abstract of assessed values. October 15 Assessor to file annual revaluation progress report with Department of Revenue. (RCW 84.41.130) October 31 Second half of current property taxes must be paid. (RCW 84.56.020) November Assessor certifies total assessed valuations to appropriate taxing districts. Assessor to determine 106% levy limitation for districts. (RCW 84.55.100) November 15 Taxing districts must file levy requirements with the County Council. (RCW 84.52.020) November 30 Taxing districts certify to Assessor the amount of taxes to be collected for district purposes. (RCW 84.52.070) December 1 Assessor to begin preliminary assessment work by this date. (RCW 84.40 040) Penalty of 8% is assessed on current year taxes delinquent on this date. (RCW 84.56.020) December 31 Applications for designated forest land, open space classification to be filed. Updated: April 5, 2000 Dept. of Assessments King County | Department of Assessments | News Services | Comments | Search Links to external sites do not constitute endorsements by King County. By visiting this and other King County web pages, you expressly agree to be bound by terms and conditions of the site. The details.