If you plan to run a food truck or trailer in King County, Washington, Public Health – Seattle & King County reviews your plans before you build, and issues the operating permit once you pass a pre-operational inspection. This is separate from the Washington L&I sticker for the trailer itself. You need both. Public Health is the food-safety side.
The steps, in order
- Read the county's Mobile Food Unit Plan Review and Permitting Guide. It has the checklist of what your plans must show.
- Submit a plan review application in the county's Public Health Permit Center, with your plans and two signed forms: the Use of Commissary Agreement and the Use of Restroom Agreement. Plans are required before construction, remodeling or a change of ownership.
- Answer your plan reviewer. The county has said initial reviews can take up to 8 to 10 weeks at current volumes, so plan your build and opening dates around that.
- Apply for the operating permit once your plans are approved. The operating fee is invoiced separately from the plan review fee.
- Schedule a pre-operational inspection at least one week before you want to open. The county says opening without one can mean closure and fees, including 50% of the annual permit fee.
What goes in the plan package
- A plan review application and the plan review fee.
- Drawings or photos of the unit (front, back and sides). For an occupied unit like a trailer you work inside, a scale interior layout that shows every piece of food-service equipment, with make and model. If the unit is already built, photos of the inside, outside, equipment and the L&I sticker.
- A water system drawing: fresh and waste tanks, water heater, pump, tubing, the hand wash sink and the three-compartment sink if you have one.
- A menu and a food preparation flow chart that says which steps happen at the commissary and which on the unit.
- A signed Use of Commissary Agreement, with scale drawings of the commissary kitchen.
- A restroom agreement and your site or route information.
- The county's operational questionnaire: hours, tank maintenance, daily setup and takedown, and cleaning schedule.
A few design rules from the county's guide that trip people up: the hand wash sink needs warm running water (100 to 120°F) and at least 5 gallons of fresh water; the waste tank must hold at least 15% more than the fresh tank; cutting and chopping is not allowed on the unit and has to happen at the commissary; cold food is held at 41°F or below and hot food at 135°F or above.
You need a commissary
King County requires an approved commissary located in King County. At minimum it needs a three-compartment sink, a mop sink for dumping wastewater and a hand wash sink. The commissary operator signs the agreement, and the county has to approve it before you operate there. Changing commissaries later costs $25 and needs county sign-off.
King County fees, 2026 schedule
| Item | 2026 fee |
|---|---|
| Plan review, new mobile operation | $1,008 covers a 4-hour base, then $252 per hour |
| Changes to an existing mobile unit | $504 covers 2 hours, then $252 per hour |
| Resubmitted plan review | $252 per hour |
| Annual mobile food unit permit | $630 (Risk 1), $1,008 (Risk 2) or $1,260 (Risk 3), based on your menu |
| Commissary change | $25 |
The permit year runs April 1 to March 31. Your first-year fee is prorated by start date: 100% if you open April through June, 75% July through September, 50% October through December and 25% January through March. The county's fee sheet is labeled "through 2026," so confirm the current schedule if you are applying in 2027.
Other things King County will ask about
- L&I sticker. L&I requires a sticker on occupied food trailers and trucks. See the Permit Pack plan-exempt check to find out which L&I path your unit takes.
- Fire department approval if you use propane, charcoal, wood or oil frying equipment.
- Food Worker Cards for every employee, and state and local business licenses.
- Local permits for where you park. The county guide points to each city's own rules, and Seattle has its own street-use permits.
Where Health Permit Pack fits
Health Permit Pack is paperwork help for the county side. You pay the county's fees yourself, at cost. We do not issue permits and the county decides every approval.
| Option | Price | What you get |
|---|---|---|
| Health Roadmap | $199 | County-specific checklist and fee estimate, commissary requirements sheet, menu and equipment list templates, 20-minute call |
| Health Packet | $449 | Everything in the Roadmap, plus we draft your full plan review packet: floor plan, equipment list, SOP answers and commissary agreement prep |
| Health Full Support | $850 | Everything in the Packet, plus we submit and track it, up to 2 correction rounds and pre-op inspection prep |
| Reciprocity filing | $149 | For units already permitted in another Washington county |
See Health Permit Pack Call or text 253-640-4848
Common questions
Do I need the county permit before the L&I sticker?
They are separate approvals. The county asks for the L&I sticker number on the plan review application and photos of it if the unit is already built, so many operators work on both together. Ask your plan reviewer how they want to see your timeline.
Can I operate in Pierce or Snohomish County with a King County permit?
Each county has its own process. If you are already permitted in one Washington county, ask the next county health department what it needs. Our reciprocity filing is for that situation.
How long does the county take?
King County has said initial plan reviews can take up to 8 to 10 weeks at current application volumes. Resubmittals are billed hourly, so a complete first package saves both time and money.