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

RCW 36.70A.681(1)(g), enacted with HB 1337, restricts Tacoma's impact fee authority under RCW 82.02: ADUs under 1,000 sq ft are exempt from city impact fees entirely, and ADUs at or above 1,000 sq ft may be charged no more than 50% of the impact fee imposed on the primary dwelling. Tacoma's traffic and park impact fee schedule under TMC 2.21 and 2.23 reflects this cap. Tacoma Public Utilities collects water and sewer capacity charges (general facility charges) under TMC 12.10 and 12.08; these are utility connection charges, not impact fees, and are not subject to the HB 1337 cap, but TPU offers reduced charges where existing capacity is already in place. School impact fees collected by Pierce County for Tacoma School District under TMC 2.23 are similarly considered impact fees and subject to the 50% cap on larger ADUs and full waiver on smaller units. Standard PDS plan review, building, mechanical, electrical, and plumbing permit fees (typically $4,000-$10,000 combined) still apply. Pre-approved DADU plans accepted by Tacoma can reduce plan review fees.