A county with an annual revaluation plan will use market data and statistical methods to annually update the assessed value for each property in the county. This method will generally result in moderate changes in value each year.
A multi-year county will inspect and appraise a portion of the county's parcels each year of the cycle. As an example, a county with a 4-year plan will inspect and appraise one-fourth of the property each year during a 4-year period. This method will generally result in a larger value change in one year and then no change in value for the next three years of the 4-year period. Washington State has counties that operate under 2-year, 3-year, and 4-year plans.