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

Under Washington RCW 36.70A.696, any impact fee imposed on an ADU in a Growth Management Act city must not exceed 50 percent of the impact fee that would apply to a primary single-family residence. Kent goes further: KCC 15.08.250 waives Park and Transportation Impact Fees entirely for the first ADU on a single-family lot and reduces them to 50 percent of the single-family rate for the second ADU. School impact fees for the Kent School District are administered separately and assessed at building permit issuance. ADU applicants still pay the building permit fee scaled to construction valuation under the Washington State Building Code fee schedule, plan-review fees, and trade permit fees for plumbing, gas, and mechanical work. Electrical permits are issued by the Washington State Department of Labor and Industries under RCW 19.28 and WAC 296-46B, not by Kent. Utility connection fees from Kent Public Works apply only if a new water meter or sewer side-sewer is required; sharing utilities with the primary dwelling avoids these charges. Stormwater fees apply if new impervious surface exceeds the threshold in KCC Title 7 (Utilities) and the city's Surface Water Design Manual.