Federal Way, WA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- Transportation fee cap
- 50% of a detached SFD fee
- Park impact fee cap
- 50% of a detached SFD fee
- Transportation citation
- FWRC 19.91.060(6)
- Park fee citation
- FWRC 19.92.060(5)
- Payment due
- Before building permit issuance
- Deferral limit
- Up to 18 months, single-family units
- Enforcing office
- Dept. of Community Development
Summary
Federal Way caps both transportation and park impact fees for accessory dwelling units at 50 percent of what a detached single-family home pays. The discount applies automatically when the city assesses fees at building permit issuance under FWRC 19.91.060 and 19.92.060.
(6) For accessory dwelling units, transportation impact fees shall not exceed 50 percent of the transportation impact fees required for a detached single-family dwelling. ... (7) The department of community development shall not issue the required building permit until a lien has been recorded pursuant to FWRC 19.100.075(3), or the transportation impact fees set forth in the fee schedule have been paid as set forth in the fee schedule or in the amounts that they exceed any credits allowable under this chapter.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 26-1049, passed August 11, 2026).
Full Breakdown
92, and both chapters give accessory dwelling units a specific break. " Both fees are generated from adopted rate studies (the transportation rate study by Fehr & Peers, dated November 2020, and the May 2023 Park Impact Fee Study) and are set out in the city's current impact fee schedule adopted by council. 060(7). 070 for park fees; either applicant pays the city's hourly review cost. 050(3)(b). Both chapters were last amended by Ord. No. 26-1044 (transportation, 6-16-26) and Ord. No. 25-1010 (park assessment, 5-6-25).
Violations & Fines
The community development department withholds the building permit until the impact fees are paid or a lien is recorded against the property under FWRC 19.100.075(3); occupancy is likewise blocked where no permit is required but the fee remains unpaid. Determinations on independent fee calculations or fee amounts can be appealed under FWRC 19.91.180 for transportation fees and FWRC 19.92.150(4) for park fees.
Frequently Asked Questions
How much is the impact fee for an ADU in Federal Way?
When does Federal Way collect ADU impact fees?
Can I get a lower ADU impact fee than the schedule shows?
Can I delay paying the transportation impact fee?
Sources & Official References
Other rules in Federal Way
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ADU Impact Fees in Nearby Cities
How other cities in King County handle adu impact fees.