Sole Proprietorship in Washington (2026)

Fact-checked by the LegalGlass editorial team against primary sources · Published Aug 20, 2026 · Last updated Aug 20, 2026

A sole proprietorship in Washington requires no state formation filing, but almost every business must file a Business License Application with the Department of Revenue's Business Licensing Service — $50 for a new business and $5 to renew, plus $5 per trade name. Washington has no personal income tax; it taxes gross receipts through the business and occupation (B&O) tax instead.

What a Sole Proprietorship Is in Washington

A sole proprietorship is an unincorporated business owned by one person. It is the default structure everywhere in the United States, including Washington: start selling goods or services on your own account and you are a sole proprietor from that moment, whether or not you ever file a document. Because the business is not a separate legal person, every dollar of profit is yours and every debt, contract, and lawsuit is also yours personally. That simplicity is the appeal, and the absence of a liability shield is the drawback.

Nothing in Washington law creates a sole proprietorship, so there is no "sole proprietor certificate" and no formation fee. What Washington does regulate is what the business does: collecting tax, hiring employees, using a business name, and practising a licensed trade. Each of those triggers a separate registration, and each is covered below. If you want a liability shield instead, compare this structure with an LLC, read S-corp vs LLC, and use the glossary for the terms used here.

No State Formation Filing Required

The Washington Secretary of State's Corporations and Charities Division registers LLCs, corporations, and limited partnerships. It does not register sole proprietorships. There is no certificate to file, no filing fee, and no annual report at the entity level — the $70 annual report and the initial report that a Washington LLC must file simply do not apply to you. Nor do you need a Washington registered agent.

Because nothing is filed with the Secretary of State, a sole proprietorship does not appear in the Washington business entity search. Your legal obligations come from the Department of Revenue, from city licensing, and from employment law. If you later decide the liability shield is worth it, the Washington LLC cost page sets out the numbers and Certificate of Formation explains the filing.

The Washington Business License Application

Washington's distinctive requirement is the Business License Application, filed with the Business Licensing Service at the Department of Revenue. It is a single application that registers you for state taxes, records any trade name, and can add many city endorsements at the same time. The Department of Revenue charges $50 to open a new business and $5 to renew; registering a trade name costs $5 per name. Individual city endorsements carry their own fees on top.

Most sole proprietors need it. You generally must apply if you will make retail sales, hire employees, use a trade name, or meet the gross-income threshold for B&O reporting. The resulting Unified Business Identifier (UBI) number is what state agencies, cities, and many customers will ask for. See how to get a Washington business licence and Washington DBA filing for the trade-name side.

Business and Occupation (B&O) Tax

Washington has no personal income tax and no corporate income tax. Instead the state levies the business and occupation tax on gross receipts — the total the business takes in, with no deduction for labour, materials, or other costs of doing business. The rate depends on the activity classification you fall into, so a retailer, a wholesaler, a manufacturer, and a service provider are taxed at different rates on the same revenue. Confirm your classification and rate on the Department of Revenue B&O tax page.

Because B&O is a gross-receipts tax, a low-margin business can owe tax in a year it makes no profit. Washington softens this with a small-business B&O tax credit and filing thresholds, so many very small proprietors owe little or nothing — but you may still have to file. Retailers also collect retail sales tax from customers and remit it, which is a separate obligation from B&O. See Washington LLC tax filing for how the same taxes apply to an entity.

EIN: When a Sole Proprietor Needs One

An Employer Identification Number is a free federal tax ID from the IRS, and it is distinct from the Washington UBI number. A sole proprietor with no employees may normally use a Social Security number instead. The EIN becomes mandatory when you hire employees, file employment or certain excise tax returns, or establish a qualified retirement plan, and most banks want one before opening a business account.

The IRS charges nothing. Its online EIN assistant issues a number immediately when the principal business is in the United States and the responsible party has a valid taxpayer identification number; Form SS-4 by fax or mail is the fallback route. Never pay a third-party site. See the national EIN guide, the ITIN page, and EIN basics.

Federal Income and Self-Employment Tax

Federally, a sole proprietorship is reported on your own return. Gross receipts and deductible expenses go on Schedule C, and net profit carries to Form 1040. On that profit you owe self-employment tax of 15.3% — 12.4% Social Security up to the annual wage base plus 2.9% Medicare with no ceiling — computed on Schedule SE. Half of it is deductible in arriving at adjusted gross income.

Because Washington has no personal income tax, your only income-tax return is the federal one, which is a genuine simplification. But no one withholds for you, so the IRS expects quarterly estimated payments on Form 1040-ES, and the Department of Revenue expects periodic B&O and sales-tax returns on its own schedule. Model the federal burden with the self-employment tax calculator and read business tax basics.

City Endorsements, Permits, and Employees

Washington cities levy their own business licences, and many of them are administered through the same state Business Licensing Service as "city endorsements" that you add to your application. Seattle, Tacoma, Bellevue and others also run their own local B&O taxes on top of the state tax. Professional and occupational activities are licensed by state boards, and food, childcare, and contracting work all require separate permits. Use the business licence overview as a framework.

Hiring adds a distinct layer: an EIN, state employment security and labour and industries registration, workers' compensation through the state fund, and Washington's Paid Family and Medical Leave premiums. Independent contractors avoid most of that, but misclassification is aggressively enforced. For the ordered sequence, see how to start a business.

Liability and When to Move to an LLC

The defining trade-off is personal liability. With no legal separation between you and the business, a supplier's unpaid invoice, a customer's injury claim, or a defaulted lease is a claim against your personal assets — savings, vehicles, and in many cases your home. Insurance narrows the exposure but does not create the separation that an entity does. A sole proprietorship also cannot be sold as a going entity, cannot admit a co-owner without becoming a partnership, and ends when you stop operating.

Most owners convert once revenue, contracts, employees, or physical risk grow. Converting means forming the entity, moving bank accounts, contracts, licences, and insurance into it, and adopting an operating agreement. Your federal EIN, tax registrations, and income-tax duties continue in the new structure, though you may need to notify the state tax agency that the taxpayer has changed. Before choosing a name, run the formation checklist, review single-member LLC treatment, and compare an LLC against a sole proprietorship.

Frequently Asked Questions

Do you have to register a sole proprietorship in Washington?

Not with the Secretary of State, which does not register sole proprietorships. But most sole proprietors must file a Business License Application with the Department of Revenue's Business Licensing Service before operating, which costs $50 for a new business and issues a Unified Business Identifier number.

How much is a Washington business licence for a sole proprietor?

The Department of Revenue charges $50 to file a new Business License Application and $5 to renew it. Registering a trade name costs $5 per name. City endorsements added through the same application carry their own separate fees set by each city.

Does a Washington sole proprietor pay income tax to the state?

No. Washington has no personal income tax and no corporate income tax. Instead the state charges business and occupation tax on gross receipts, at a rate that depends on your activity classification, and retailers separately collect and remit retail sales tax.

What is B&O tax and does a sole proprietor owe it?

The business and occupation tax is a Washington tax on gross receipts with no deduction for costs, so a sole proprietor can owe it even in an unprofitable year. Rates vary by classification. A small-business credit and filing thresholds mean many very small proprietors owe little or nothing.

Does a Washington sole proprietor need an EIN?

Not usually. A sole proprietor with no employees can use a Social Security number. An EIN is required if you hire employees, file employment or certain excise tax returns, or set up a qualified retirement plan. It is free from the IRS and is separate from the Washington UBI number.

Related

• Sole proprietorship (cluster hub)
• How to form an LLC in Washington
• Washington business licence
• Washington DBA filing
• Washington LLC tax filing
• How to get an EIN
• Sole proprietorship in Hawaii (sibling)
• Sole proprietorship in Nevada (sibling)

Sources

1. Washington Department of Revenue — Apply for a Business License.
2. Washington Department of Revenue — Business License Processing Fees ($50 new business; $5 renewal; $5 trade name).
3. Washington Department of Revenue — Business and Occupation Tax.
4. Washington Department of Revenue — Register Trade Names.
5. Revised Code of Washington — RCW 82.04.4451, small business B&O tax credit.
6. Washington Secretary of State — LLC Filing Resource Page (entity registration scope).
7. IRS — Sole Proprietorships.
8. IRS — About Schedule C (Form 1040).
9. IRS — Self-Employment Tax (Social Security and Medicare Taxes) (15.3%).
10. IRS — About Schedule SE (Form 1040).
11. IRS — Get an Employer Identification Number (free EIN).
12. IRS — Do You Need an EIN?
13. IRS — Estimated Taxes (Form 1040-ES).
14. U.S. Small Business Administration — Choose a Business Structure.

LegalGlass provides general information for educational purposes and is not legal advice, is not a law firm, and is not a substitute for advice from a licensed attorney or tax professional. Laws, fees, and thresholds change; verify current requirements with the Washington Department of Revenue, the Washington Secretary of State, and the IRS before acting.