King County, WA Zoning Overlays & Bonuses: Density Bonus Law (2026)
Key Facts
- Bonus unit trigger
- 1 unit per 6 daycare slots
- Max density bonus
- 25% above base
- Alternate bonus
- 1,000 sq ft floor area per 6 slots
- Affordable slot minimum
- 20% at or below 80% AMI
- Dedication term
- At least 20 years
Summary
Unincorporated King County developments get bonus density or floor area for adding improved child daycare slots, up to 25% more dwelling units than the base zone allows.
For every six child daycare slots provided, the development shall receive one of the following:
1. One additional bonus dwelling unit, up to an additional twenty-five percent of base density; or
2. One-thousand square feet of nonresidential floor area added to the floor area ratio maximum.
C. At least twenty percent of child daycare slots shall be reserved for households at or below eighty percent AMI. Daycare slots for individuals receiving a childcare assistance or subsidy from a public agency shall be considered to meet this requirement.
D. The child daycare facility shall obtain an operating license from the Washington state Department of Children, Youth, and Families, receive all necessary permits or approvals, and comply with all applicable state and local regulations governing the operation of licensed child daycare providers.
E. Child daycare facilities under this section shall operate for at least eight hours per day, five days per week, and forty-eight weeks per year, except that facilities serving school-aged children may operate for four hours per day.
F. Child daycare facilities under this section shall be dedicated to child daycare use for at least twenty years. Property owners shall include provisions for lease renewal of child daycare providers.
G. Before issuance of the certificate of occupancy for the development, the applicant shall:
Full Breakdown
Under K.C.C. 21A.12.270, urban-area developments in unincorporated King County earn one bonus dwelling unit (up to 25% above base density) or 1,000 square feet of added nonresidential floor area for every six child daycare slots built into the project. At least 20% of those slots must go to households at or below 80% of area median income, and the developer must record a 20-year covenant dedicating the space to daycare use before occupancy is granted. This applies only outside Seattle, Bellevue, Kent, Renton, and the county's other incorporated cities, which set their own zoning.
Violations & Fines
The King County Department of Local Services - Permitting Division reviews compliance before issuing a certificate of occupancy; a project cannot receive its bonus density or the added floor area without the recorded 20-year covenant and a signed daycare operator agreement on file.
Frequently Asked Questions
Does this density bonus apply inside Seattle or other cities?
What counts as an 'improved' daycare facility for the bonus?
Sources & Official References
Other rules in King County
Compare King County to another location·View the Washington zoning overlays & bonuses overview
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