If you run a consulting firm, agency, software company, or any service business in Washington, the Business & Occupation (B&O) tax is the state tax most likely to catch you off guard. Washington has no personal or corporate income tax — a genuine advantage — but it raises revenue in a way many owners don’t expect: by taxing your gross receipts rather than your profit. Here’s how the B&O tax actually works, who owes it, and how to plan for it so it never becomes an April surprise.

What is the Washington B&O tax?

The B&O tax is a tax on the gross income of your business — your total revenue before expenses. Unlike an income tax, it does not allow deductions for the costs of doing business such as labor, rent, or materials. That distinction is the single most important thing to understand: a service business with thin margins can still owe meaningful B&O tax because the tax is calculated on what you bring in, not what you keep.

The tax rate you pay depends on your business classification. Washington assigns different activities (retailing, wholesaling, manufacturing, service, etc.) to different classifications, each with its own rate.

Why it surprises service business owners

Most service and software businesses fall under the “Service & Other Activities” classification, which carries one of the higher B&O rates. New owners frequently assume “no income tax” means “no state tax on my business” — then receive a bill calculated on every dollar of revenue. Because there are no expense deductions, the tax can feel disproportionate in a low-margin year.

Plan, don’t panic. The B&O tax is predictable. Once you know your classification and rate, it’s a straightforward percentage of revenue you can accrue for every month — the way you’d accrue for payroll taxes — rather than scrambling at filing time.

Which classification applies to you?

Service businesses — consultants, agencies, IT and managed-service providers, SaaS companies, professional-service firms — generally report under Service & Other Activities. Some businesses have multiple revenue streams that fall under different classifications (for example, reselling software vs. providing services), and each stream is taxed at its own rate. Getting the classification right matters: misclassifying revenue can mean overpaying, or underpaying and facing back taxes.

B&O rates and thresholds are set by the Washington Department of Revenue and change periodically. Always confirm the current rate for your classification on the DOR’s published schedule, or have your accountant confirm it for your specific revenue mix.

Don’t forget Seattle’s city B&O tax

On top of the state B&O tax, the City of Seattle levies its own B&O tax, with its own rates and its own filing requirements. Several other Washington cities do the same. Many Seattle businesses owe both. There is typically a gross-revenue threshold below which the city tax doesn’t apply, so very small businesses may owe nothing to the city — but you usually still need to register and, in some cases, file a return showing you’re under the threshold.

Credits and the small business B&O credit

Washington offers a Small Business B&O Tax Credit that can reduce — or in some cases eliminate — the state B&O tax for businesses with lower gross income. The credit phases out as revenue rises. There are also industry-specific deductions and credits. These are easy to miss if you’re filing on your own, and they’re a common place where a service business leaves money on the table.

How often do you file?

Washington assigns each business a filing frequency — monthly, quarterly, or annual — based primarily on your expected tax liability. Higher-revenue businesses file more often. Returns are filed and paid through the DOR’s online system, and late filings carry penalties and interest, so calendaring your due dates is essential.

How to plan for B&O tax (and stop dreading it)

  • Confirm your classification and current rate so you know the exact percentage of revenue at stake.
  • Accrue monthly. Set aside the B&O amount as revenue comes in, so the cash is there at filing time.
  • Track state and city separately — they’re different taxes with different rules.
  • Apply every credit you qualify for, including the small business credit.
  • Build it into pricing. Because B&O is a cost of every dollar of revenue, factor it into your rates the way you would any other cost of doing business.

This is exactly the kind of year-round planning we build into our monthly close for Seattle clients. If you’d rather never think about B&O deadlines again, our Seattle accounting and bookkeeping team handles the calculation, accrual, and filing for you — alongside your federal and state tax work and day-to-day bookkeeping.

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Frequently asked questions

Does my service business owe B&O tax even if it isn’t profitable?

Usually yes. The B&O tax is based on gross receipts, not profit, so a business can owe B&O tax in a year it shows no net income. Credits like the small business B&O credit may reduce or eliminate the amount for lower-revenue businesses.

What classification do most service businesses use?

Most consultants, agencies, software firms, and professional-service businesses report under “Service & Other Activities.” Businesses with mixed revenue may report multiple classifications.

Do I owe Seattle city B&O tax in addition to the state tax?

Often, yes. Seattle administers its own B&O tax separate from the state’s, with its own rates and thresholds. Many Seattle businesses file and pay both.

How do I stop missing B&O deadlines?

Have your accountant calculate, accrue, and file it as part of your monthly close. That turns a stressful, easy-to-miss task into a routine line item.

This article is general information, not tax advice. B&O rates, thresholds, and rules change — confirm current figures with the Washington Department of Revenue or your CPA before acting.