Will I have to pay impact fees on an ADU in Washington?
✓ Verified against code · August 19, 2026
It depends heavily on your city — state law doesn't set or waive impact fees. Kent exempts the first ADU entirely from school, transportation, and park impact fees, with a second ADU paying half the single-family rate. Renton's PRADU pre-approved plans waive several impact fees outright, with some utility connection charges cut by roughly 30% instead of eliminated. Everett waives traffic impact fees for the first ADU. Edmonds, by contrast, charges in full: park impact fees moved to $1.35 per sq ft of residential space in 2026, plus transportation and sewer facility charges. Ask your city's permit center for its current fee schedule.
Citation: varies by city — see city pages
How current is this?
Washington’s ADU rules run under HB 1337 (2023). HB 1337 required every Washington city over 25,000 people to allow two ADUs per residential lot, drop owner-occupancy requirements, cap size limits no lower than 1,000 sq ft, cap height limits no lower than 24 ft, and stop requiring parking near major transit — with compliance due June 30, 2025 for larger cities. We verified this answer against primary sources on August 19, 2026, and every change we catch is logged in the changelog.
More Washington ADU questions
- How many ADUs can I build in Washington?
- What is HB 1337?
- Do I need parking for an ADU in Washington?
- Can cities require me to live on the property?
- How big can an ADU be in Washington?
- Can I sell an ADU separately in Washington?
- Which WA cities have pre-approved ADU plans?
- When did WA ADU rules change?
- How tall can an ADU be in Washington?
- How close to my property line can an ADU be built?
- How long does it take to get an ADU permit in Washington?
Not legal advice — local ordinances can go further than the state floor. The citation above points at the governing statute; check your city’s code for the specifics.