Spokane, WA Accessory Structures: ADU Impact Fees (2026)

Washington HB 1337 (Laws of 2023, ch. 332), codified at RCW 36.70A.681, prohibits Spokane from charging any impact fees on an ADU under 1,000 sq ft and caps impact fees on ADUs 1,000 sq ft or larger at 50% of the impact fee charged on a single-family detached home. This applies to all impact fees authorized under RCW 82.02.050 (school, parks, transportation, fire). Spokane has not adopted school or parks impact fees - the city's primary impact fee is the Transportation Impact Fee under SMC 17D.075, which funds capital improvements identified in the Six-Year Transportation Improvement Program. Standard ADUs in Spokane therefore pay only Spokane Permit Center building permit fees (typically $2,500-$6,000 for plan review, building, mechanical, electrical, and plumbing combined), water/sewer capacity charges, and stormwater fees through SMC Chapter 13.05 (Stormwater). Spokane County Building Health District fees may apply. Washington State Environmental Policy Act (SEPA) review is typically not required for single ADUs under WAC 197-11-800 categorical exemptions. Pacific Power / Avista Utilities electric service connection charges apply separately and are not impact fees. The Mandatory Inclusionary Housing program has not been adopted in Spokane, so ADUs are not subject to any affordability covenant.