King County, Washington business licensing guide
Accuracy date: May 18, 2026. Last updated: May 18, 2026. Next review: September 18, 2026.
Starting a business in King County can involve several layers: Washington state, King County, Seattle or another city, zoning, health permits, building or fire permits, and sometimes a state professional license.
The most important first step is not filling out a form. It is finding out whether your business location is inside Seattle, inside another King County city, or in unincorporated King County. That answer usually decides which local office controls your business license, zoning approval, and local tax filings.
Bottom line
King County is not the same thing as Seattle. It is also not the same thing as the Washington state business license system.
For many small businesses, the local business license or local tax filing is handled by the city where the business is located or where the business does work. Seattle, for example, has a Seattle business license tax certificate and city business taxes. Other King County cities may use Washington’s Business Licensing Service, FileLocal, their own city system, or a mix of local rules.
King County itself issues business licenses only for certain regulated business types in unincorporated King County. If your business is inside city limits, you normally need to check that city first for local licensing, zoning, building, fire, mobile vending, short-term rental, and local tax rules.
You may still need Washington state registration through the Department of Revenue, an entity filing with the Washington Secretary of State, a trade name registration, employer accounts, professional licensing, food permits, contractor registration, or other industry-specific approvals.
Start here: check whether your address is in a city or unincorporated King County
Before you pay for a license or file a local application, confirm the jurisdiction for the exact business address. A mailing address that says Seattle, Renton, Kent, Bellevue, Federal Way, Auburn, Redmond, Shoreline, or another city does not always answer the legal jurisdiction question by itself.
- Look up the address. Use King County property research tools, the King County Parcel Viewer, or the county’s Property and Permit Guide for unincorporated-area questions.
- Confirm whether the business is inside a city. If the address is inside Seattle or another incorporated city, the city usually controls local business licensing and zoning.
- If the address is unincorporated, check King County Local Services. King County Permits handles land use, building, mechanical, fire regulatory and operating permits, code enforcement, and some business licenses for unincorporated King County.
- Check Washington state registration. Washington’s Department of Revenue handles the Business License Application, UBI number, state endorsements, many city endorsements, trade names, and tax accounts.
- Check your business type. Food, mobile vending, contractors, taxis, short-term rentals, cannabis, massage, entertainment, pawn/secondhand, pet businesses, childcare, alcohol, and professional services may have extra rules.
Practical tip: Keep a simple folder with your business address, parcel or suite number, city or unincorporated status, business activities, trade name, state UBI number, lease or owner permission, and any food, building, fire, or professional license documents.
How the license layers work in King County
| Layer | What it may control | Where to check |
|---|---|---|
| Washington state | Business License Application, UBI number, state tax accounts, state endorsements, trade names, employer registration steps, some city endorsements, professional or industry licensing. | Washington Department of Revenue, Washington Secretary of State, Department of Licensing, Labor & Industries, Employment Security Department, and other state agencies. |
| King County | Limited business licenses for certain regulated activities in unincorporated areas, unincorporated zoning, land use, building, mechanical, fire regulatory and operating permits, code enforcement, food and environmental health permits, and business personal property tax reporting. | King County Department of Local Services, King County Permits, Public Health – Seattle & King County, and King County Assessor. |
| Seattle | Seattle business license tax certificate, Seattle B&O tax and other city taxes, regulatory endorsements, street-use permits, zoning, building, fire, and short-term rental rules. | City of Seattle Office of City Finance, Seattle Services Portal, Seattle Department of Construction and Inspections, Seattle Department of Transportation, and other city departments. |
| Other King County cities | City business licenses, city endorsements, local B&O or other city taxes where applicable, zoning, home occupation rules, sign permits, building/fire approvals, mobile vending, and local operating rules. | The city business license office, city finance office, city clerk, planning/zoning department, building department, fire marshal, DOR city endorsements, or FileLocal if the city participates. |
| Federal or private layer | EIN, federal tax rules, alcohol/tobacco/firearms rules, transportation rules, platform seller requirements, insurance, lease rules, and payment processor requirements. | IRS, federal agencies, landlord or property manager, insurer, marketplace platform, or professional adviser. |
King County business license, tax, and permit layer
King County’s business license role is limited. The county says you need a King County business license only if the business is engaged in a regulated activity and is located in unincorporated King County, meaning outside city limits.
That means a normal online seller, freelancer, consultant, small retailer, or home business in Seattle, Bellevue, Kent, Renton, Redmond, Federal Way, Shoreline, Auburn, Kirkland, or another city should not assume King County is the local business license office. The city and Washington state may be more important for the local business license layer.
King County regulated business licenses in unincorporated areas
King County lists several regulated business license categories for unincorporated King County. Examples include adult beverage, amusement and dance places, amusement devices, carnivals, charitable solicitation, entertainers and managers, go-cart tracks, junk shops and wagons, massage and bathhouse licenses, outdoor musical entertainment, pawnshops, retail marijuana, secondhand dealers, shooting ranges, and theaters.
Do not assume this list applies inside a city. If the business is inside a city, check that city and any state agency that regulates the activity.
King County zoning for unincorporated businesses
All businesses in unincorporated King County must follow zoning rules. King County states that business premises in unincorporated areas must be compatible with the zoning or permitted uses allowed for that location. For a home business in unincorporated King County, a separate King County business license is not required unless the business is a regulated activity, but the business still must comply with home occupation zoning requirements.
For unincorporated locations, check the property’s zoning before signing a lease, buying equipment, or applying for a regulated business license. King County’s zoning FAQ says the first step is finding the property’s zoning and then reviewing the permitted-use tables in the King County Code.
Building, land use, mechanical, and fire permits in unincorporated King County
King County Permits provides land use, building, mechanical, fire regulatory and operating permits, code enforcement, and a limited number of business licenses for unincorporated areas. This matters if you are building out a space, changing a use, adding signs or equipment, creating a commercial kitchen, using hazardous materials, hosting certain events, or making changes that could require a permit.
For city locations, use the city building, planning, zoning, fire, and public works offices instead of assuming King County Permits controls the approval.
Business personal property tax reporting
King County’s business license page states that all businesses in King County are required to file a personal property tax affidavit. King County Assessor also provides eListing for reporting business personal property used in the business. This is separate from a business license, state tax registration, or city B&O tax return.
If you own or use business equipment, furniture, fixtures, computers, supplies, leasehold improvements, or other business personal property, check the King County Assessor’s personal property tax instructions. Do not treat the affidavit as the same thing as a city license or Washington state business license.
Seattle and other city business license rules
If your business address is inside a city in King County, the city usually controls the local business license, local tax, zoning, home occupation, storefront, sign, building, fire, and right-of-way permit questions.
Seattle
The City of Seattle says anyone doing business in Seattle must have a Seattle business license tax certificate, also called a business license or general business license. Seattle also has city business taxes, including a Seattle B&O tax on gross income. Seattle states that the Seattle business license tax is not the same as Washington State B&O tax, and Seattle taxes must be filed separately from state taxes.
Seattle also regulates certain business types with regulatory endorsements or separate city approvals. Examples may include short-term rentals, towing, taxis, marijuana businesses, adult entertainment, street or sidewalk vending, and other regulated activities. A Seattle business may also need approvals from Seattle zoning, building, fire, transportation, or public health agencies depending on the activity.
Other King County cities
Many King County cities have their own local licensing or tax rules. Some city endorsements can be added through the Washington Department of Revenue’s Business Licensing Service. If a city is not handled through DOR’s endorsement list, the DOR page tells businesses to contact that city directly.
FileLocal is another official local portal used by several cities for general business licenses and local business taxes. FileLocal lists participating cities including Auburn, Bellevue, Des Moines, Kent, Lake Forest Park, Renton, Seattle, and Shoreline, among others outside King County.
Because cities use different systems, do not assume one King County-wide city process. A business in Bellevue may not have the same process as a business in Seattle, Renton, Kent, Redmond, Kirkland, Federal Way, Shoreline, Auburn, Tukwila, Issaquah, Sammamish, or a smaller city.
If your business travels into several cities
Mobile service businesses, contractors, vendors, delivery businesses, entertainers, consultants, and event businesses should ask whether they need a city license or tax account for each city where they conduct business. Washington DOR’s city endorsements page says that if your business is physically located in, or will travel to, listed cities, you can apply for their endorsements when filing state licenses and registrations. For cities not listed, contact the city directly.
This is important for businesses that are based at home in one jurisdiction but perform work in another. A home base in unincorporated King County does not automatically cover work inside Seattle. A Seattle business license does not automatically satisfy every suburban city’s rules.
Trade names, DBA, and business names in Washington
Washington generally uses the term trade name for a business name used by a business that is not the owner’s full legal name or the entity’s exact legal name. This is the Washington equivalent of what many people call a DBA or assumed name.
Trade names are handled through the Washington Department of Revenue’s Business Licensing Service, not through a King County clerk DBA filing system. DOR says you can register a trade name by filing a Business License Application through My DOR and paying the trade name fee and the Business License Application processing fee.
A trade name is not the same thing as forming an LLC or corporation. If you want to create a Washington LLC, corporation, or other registered entity, check the Washington Secretary of State first. DOR says certain business structures must file with the Secretary of State before filing the Business License Application.
Do not confuse these names: A Washington Secretary of State entity name, a DOR trade name, a city business license, a trademark, a domain name, and a social media handle are different things. Registering one does not automatically secure all the others.
Washington state registrations and taxes
Most King County businesses should check the Washington Department of Revenue before they open. Washington’s Business License Application can create a state business license, assign a Unified Business Identifier number, add state endorsements, add many city endorsements, register trade names, and set up tax accounts.
DOR lists several situations where a business must register and get a business license. These include needing city, county, or state endorsements; doing business under a name other than the owner’s full legal name; planning to hire employees within 90 days; selling products or services that require sales tax collection; reaching the gross income threshold listed by DOR; owing DOR-administered taxes or fees; or meeting certain nexus rules.
UBI number
When you receive a Washington business license, you are assigned a Unified Business Identifier, often called a UBI number. You may need this number for state tax filings, city licensing systems, FileLocal, professional licensing, contractor registration, and updates to the business.
State taxes and sales tax
Washington does not use a personal or corporate income tax system in the same way many states do, but businesses may have Washington B&O tax, retail sales tax, use tax, and other state tax duties depending on their activities. Cities such as Seattle may also have local business taxes that are separate from Washington state taxes.
If you sell taxable products or taxable services, ask DOR whether you need to collect sales tax, file excise tax returns, obtain a reseller permit, or report under a specific tax classification.
Employers
If you plan to hire employees, update or file the state business license application and check Washington Employment Security Department and Labor & Industries requirements. Employer rules may include unemployment tax, workers’ compensation, workplace safety, wage and hour rules, and required workplace posters.
State professional and industry licenses
Some businesses need a state professional or industry license in addition to local licenses. Examples may include contractors, electricians, plumbers, real estate professionals, cosmetology and barbering, healthcare professions, vehicle-related businesses, childcare, alcohol, cannabis, and certain transportation businesses.
Contractors should check Washington Labor & Industries. L&I contractor registration materials refer to the business name, business structure, or DOR business registration and UBI number as part of the contractor registration process. The Washington Department of Licensing also maintains professional license information for many professions and businesses.
Zoning, home occupation, health, building, fire, and industry permits
A business license is not the same as permission to use a property. A business can have a state UBI number and still fail zoning, building, health, fire, or lease requirements.
Zoning and home businesses
For unincorporated King County, check King County zoning and home occupation rules. King County says each city has jurisdiction over its own zoning, land use, and permits, while King County manages those items for unincorporated areas.
For a home-based business inside Seattle or another city, check that city’s home occupation rules. A city may limit customer visits, employees, signage, deliveries, outdoor storage, commercial vehicles, noise, odor, or changes to the residential character of the property.
Food businesses
Public Health – Seattle & King County issues food business permits for local businesses and community feeding programs. It also reviews and approves construction plans for retail food businesses such as restaurants, caterers, commercial commissary kitchens, grocery stores, school cafeterias, and mobile food vehicles.
Food permit categories include permanent food businesses, mobile food businesses, temporary event food businesses, farmers markets, catering and home-based food businesses, beverage-related businesses, and commercial commissary kitchens. Public Health also points cottage food and wholesale food operations to the Washington State Department of Agriculture.
If you sell food from a truck, cart, tent, farmers market booth, shared kitchen, home kitchen, catering setup, or event booth, check health permits before buying equipment or signing an event contract.
Building, fire, signs, and tenant improvements
Storefronts, restaurants, salons, offices, warehouses, fitness studios, childcare spaces, manufacturing spaces, and event venues may need building, occupancy, fire, mechanical, plumbing, electrical, sign, or tenant improvement approvals.
For unincorporated King County, start with King County Permits. For Seattle or another city, use that city’s building and fire departments. Some specialty permits may be handled by other agencies. For example, King County’s permit guide points some electrical permits to Washington Labor & Industries, and food business permits to Public Health.
Mobile vendors and use of streets or sidewalks
A mobile food business may need a state business license, local city license, health permit, commissary or plan review, fire approval, and a street-use or right-of-way permit if operating on public streets or sidewalks. Seattle’s transportation department handles vending permits in the public right-of-way, while Public Health – Seattle & King County handles food permits for food vendors.
For vending on private property, also check zoning, property-owner permission, parking lot rules, restroom access, fire rules, and city location restrictions.
Short-term rentals
Short-term rental rules are highly local. Seattle has a short-term rental regulatory license system through the Seattle Services Portal. Other cities in King County may have their own rules, zoning limits, business license requirements, taxes, inspections, or housing rules. Do not assume King County has one countywide answer for every short-term rental.
What common business types should verify
Home-based business
Check the address jurisdiction, then check state registration, trade name, city or county home occupation rules, customer visits, employees, signage, parking, deliveries, equipment, and whether the activity is allowed at a residence.
Online seller or creator
Check DOR registration, trade name, sales tax, marketplace rules, city licensing if the business is based in a city, and home occupation rules if you operate from home. Inventory storage, product pickup, customer visits, or frequent shipments may create zoning issues.
Mobile service business
Check state registration, DOR city endorsements, FileLocal or city tax accounts, and whether each city where you work requires a local license. Contractors, cleaners, landscapers, mobile mechanics, photographers, entertainers, and consultants should not assume the home city license covers every city where services are performed.
Food business
Check Public Health – Seattle & King County before operating. Food businesses may need health plan review, a food business permit, a food worker card, commissary approval, mobile food approval, temporary event approval, city business license, fire approval, and zoning clearance.
Contractor or trades business
Check Washington Labor & Industries contractor registration or trade licensing, DOR registration, city license rules for where work is performed, building permit rules, bonding and insurance requirements, and whether subcontractor or employee rules apply.
Storefront, salon, studio, or office
Check the city or King County zoning office before signing a lease. Then check state registration, city business licensing, certificate of occupancy or tenant improvement permits, sign permits, fire inspections, health or professional licensing, and landlord requirements.
Common mistakes to avoid
- Assuming Seattle rules apply to all of King County. Seattle has its own business license tax certificate and city tax system. Other cities and unincorporated areas are different.
- Assuming King County issues one general business license for every business. King County’s own business licenses are limited to certain regulated activities in unincorporated King County.
- Skipping the jurisdiction check. City limits, mailing addresses, school districts, fire districts, and ZIP codes are not always the same thing.
- Confusing a DOR trade name with an LLC. A trade name does not create a separate legal entity.
- Confusing Seattle B&O tax with Washington State B&O tax. Seattle says its city business license tax is separate from the state tax system.
- Opening a food business before health plan review. Restaurants, mobile food vehicles, caterers, commissaries, and temporary food vendors may need approvals before operating.
- Signing a lease before zoning review. A property may not allow the use you want, or may need permits before opening.
- Ignoring business personal property reporting. King County has a separate business personal property tax reporting layer.
- Relying on a filing company instead of official sources. A paid filing service may not check your city zoning, health permit, fire permit, or local tax responsibilities.
What to ask before paying for or filing anything
Before calling or emailing an agency, write down your business name, owner name, exact address, whether the business is home-based, mobile, online, storefront, or food-related, and the cities where you will do business.
Phone or email script
Hello, I am trying to confirm the correct business license and permit steps for a [business type] at [address or general location] in King County. Can you help me confirm whether this location is inside [city name] or unincorporated King County? I also need to know whether I should apply through Washington DOR, the city, King County Permits, Public Health – Seattle & King County, FileLocal, or another agency.
The business will be [home-based / mobile / storefront / online / food-related], and it will [briefly describe activities]. Are there zoning, home occupation, business license, city tax, health, building, fire, sign, right-of-way, or professional license approvals I should check before opening?
Questions to ask the city or county
- Is my address inside your city limits, or is it unincorporated King County?
- Do I need a local business license, city endorsement, business license tax certificate, or local tax account?
- Do I apply through your city, Washington DOR, FileLocal, or another portal?
- Does my use comply with zoning at this address?
- Do I need a home occupation approval, certificate of occupancy, tenant improvement permit, sign permit, fire inspection, or right-of-way permit?
- If I work in multiple cities, do I need a license or tax filing in each city?
Questions to ask Public Health – Seattle & King County
- Does this food activity require a permit, plan review, commissary agreement, or inspection?
- Is my activity treated as permanent, mobile, temporary event, farmers market, catering, home-based, cottage food, or another category?
- Should I apply through the Public Health Permit Center or a state agency such as the Washington State Department of Agriculture?
Official sources
- King County business licenses
- King County Permits
- King County permits, inspections, and codes for buildings and land use
- King County property research tools
- King County zoning information
- King County Property and Permit Guide
- Public Health – Seattle & King County food business permits
- Public Health Permit Center
- King County Assessor personal property taxes
- King County eListing for business personal property
- Washington Department of Revenue – apply for a business license
- Washington Department of Revenue city endorsements
- Washington Department of Revenue trade names
- Washington Secretary of State start or register a business
- Seattle business license tax certificate
- Seattle business taxes
- FileLocal participating city license and tax portal information
- Seattle business regulations and regulatory endorsements
- Seattle short-term rental regulations
- Seattle vending permits in the public right-of-way
- Washington Labor & Industries contractor registration
- Washington Department of Licensing professional licenses
- Washington Employment Security Department employer tax guidance
- Washington State Department of Agriculture cottage food program
FAQ
Does King County have a general business license for every business?
No. King County’s own business license page says a King County business license is needed only when the business is engaged in a regulated activity and is located in unincorporated King County. Many businesses instead need to check Washington state and the city where they are located or where they do business.
If my business is in Seattle, do I apply to King County for the local business license?
Usually no. Seattle has its own business license tax certificate and city tax rules. A Seattle business may still need state registration, Public Health permits for food activities, and other approvals, but the Seattle local license layer is handled by the City of Seattle.
What if my business is in unincorporated King County?
Check Washington DOR for the state business license layer, then check King County Permits for zoning, land use, building, mechanical, fire regulatory and operating permits, code enforcement, and any regulated King County business license category that applies to your activity.
Where do I register a DBA in King County?
Washington generally uses the term trade name. Trade names are registered through the Washington Department of Revenue’s Business Licensing Service, not through a separate King County DBA office. If you are forming an LLC or corporation, check the Washington Secretary of State first.
Do I need both a Washington state business license and a Seattle business license?
You may need both. Washington’s state business license and UBI number are handled through DOR. Seattle has a separate business license tax certificate and city tax filing system for businesses doing business in Seattle. Check both official systems before operating.
Does a state UBI number prove my business location is zoned correctly?
No. A UBI number is not zoning approval. You still need to check the city zoning office or King County zoning rules for unincorporated areas before operating from a home, storefront, warehouse, kitchen, studio, or event location.
Who handles food permits in Seattle and King County?
Public Health – Seattle & King County handles many food business permits and plan reviews, including restaurants, caterers, commissary kitchens, grocery stores, school cafeterias, and mobile food vehicles. Some food activities, such as cottage food and wholesale food operations, may be handled by the Washington State Department of Agriculture.
Can I run a business from home in unincorporated King County?
Maybe. King County says a home business in unincorporated King County does not need a special county business license unless it is engaged in a regulated activity, but it still must comply with home occupation zoning requirements. Check zoning before operating.
Do mobile businesses need licenses in every King County city?
They may. If you travel to multiple cities for work, check Washington DOR city endorsements, FileLocal, and each city where you conduct business. Some cities require a local license or local tax account even if your home office is somewhere else.
Should I pay a filing company before checking official sources?
Be careful. Filing companies may help with certain forms, but they may not check your exact city, zoning, food permit, building, fire, or local tax requirements. Use official city, county, and state sources before paying for anything.
Informational disclaimer
This guide is for general informational purposes only. It is not legal, tax, accounting, insurance, zoning, or professional licensing advice. Business license and permit rules can change, and your requirements may depend on your exact address, business activity, ownership structure, employees, products, services, and city. Always confirm requirements with the official city, county, state, and federal agencies before filing, paying fees, signing a lease, or opening to the public.