WA SB5529

Expands eligibility for the accessory dwelling unit (ADU) property tax exemption from counties with 1,500,000+ population to include cities and counties located in counties with populations between 900,000 and 1,500,000

Requires local legislative authorities in the newly eligible counties to pass a resolution authorizing the exemption before it can be offered within their jurisdiction

Limits the exemption in counties with 900,000-1,500,000 population to detached ADUs only, while larger counties may include attached or detached units

Accelerates the Joint Legislative Audit and Review Committee's required program evaluation from December 1, 2029 to December 1, 2027

Takes effect July 27, 2025, applies to taxes levied for collection in 2026 and thereafter, and expires January 1, 2034