Understanding the MID Assessment Formula
The MID’s assessment formula was updated as part of the 2013 renewal process in an effort to create more transparency and predictability while maintaining previous efforts to ensure different property types are assessed fairly. In addition to a base formula, several “ceilings” come into effect for specific property types. An inflationary factor is applied to most years of the assessments, while property values are updated twice during the ten years using the King County Tax Assessor data. The cumulative inflation factor is calculated by multiplying the annual CPI by all the previous annual CPIs since 2013.
Annual MID assessments are calculated from a formula prescribed in the MID’s authorizing ordinance that was adopted in May 2013.
The following also provides a detailed explanation of the Assessment timeline, formula rationale and ceilings.