The Retailing B&O rate is 0.471 percent. The base Service and Other Activities rate is 1.5 percent. On $500,000 in gross revenue, filing under the wrong classification is a $5,145 difference in state B&O tax. That gap gets wider once you are in the higher tiers Washington added to the Service rate in late 2025, and wider still if you also owe retail sales tax that you never collected.

Washington taxes gross receipts, not profit. There is no deduction for what you spent to earn the revenue. The classification you file under determines your rate and, in some cases, whether you also owe retail sales tax on top of it. Most service business owners do not discover a classification error until DOR finds it for them, and by then the calculation includes several years of interest and penalties.

What the B&O classification system actually is

Washington's Business and Occupation tax sorts business activity into dozens of categories. The classification is not determined by your industry or your business license. It is determined by what your business actually does in each transaction, and a single business can have more than one if it does more than one type of activity.

Most Washington service businesses fall under one of three.

Service and Other Activities covers attorneys, consultants, agencies, designers, IT firms, and most businesses that sell expertise or time. Per the Washington Department of Revenue, this classification has three tax rates since October 1, 2025: 1.5 percent for prior-year taxable income subject to this classification under $1 million, 1.75 percent for $1 million to just under $5 million, and 2.1 percent for $5 million or more. The tier is determined by prior-year taxable income subject to this classification, not by current-year gross receipts or by income reported under other classifications.

Retailing applies when you sell tangible personal property or certain services directly to the end user. The current Retailing rate is 0.471 percent per DOR. Businesses that file under Retailing must also collect and remit retail sales tax from their customers, which is a separate filing obligation.

Wholesaling applies when you sell to a business that will resell, or when you work as a subcontractor for a general or prime contractor who gives you a reseller permit. The current Wholesaling rate is 0.484 percent per DOR.

The most expensive mistake: contractors filing as Service

A general contractor who bids a project and bills the property owner directly is classified as Retailing in Washington, even if the job is 100 percent labor. The contractor collects retail sales tax from the property owner and pays B&O at 0.471 percent. That is what Washington DOR's guidance requires.

A subcontractor on that same project, hired by the GC rather than the property owner, is Wholesaling at 0.484 percent and does not collect retail sales tax from the prime contractor, but only if the GC provides a reseller permit. Without a reseller permit on file, the subcontractor is classified under Retailing and has to collect retail sales tax from the GC. Getting that permit before the first invoice is the step subcontractors skip.

Many contractors have been filing under Service and Other Activities because the label sounds like a reasonable fit. The problem is that a contractor who filed as Service for three years and never charged sales tax now has two separate issues. DOR may assess the B&O difference on the rate, and it may also assess the retail sales tax that should have been collected and remitted. On $400,000 in annual billings on taxable construction work, the sales tax liability alone can become substantial quickly.

The reverse error also happens. Some trades file under Retailing but do not charge retail sales tax because they assume labor is exempt. In Washington, labor associated with improvement to real property is generally taxable. Not charging it means the liability is accumulating on every invoice.

When your business does more than one thing

A landscaping company that does weekly lawn maintenance and also installs irrigation systems may have two separate B&O classifications. An IT firm that manages networks and also sells hardware has two classification lines on its DOR return. A consultant who also licenses software products she built runs into the same split.

Most business owners discover this on the DOR online return, which prompts you to separate receipts by classification. If you have been putting everything on a single line, you have been paying one rate on income that should have been split, in whichever direction that error runs.

This comes up more often than you might expect. Any business that sells its time and occasionally sells a tangible product, or provides both taxable and nontaxable services, needs to report each separately.

The deductions that most service businesses never claim

Washington B&O is on gross receipts, but several deductions reduce what actually counts as taxable.

Out-of-state work is the most commonly missed. If you perform services for clients located outside Washington and the benefit of those services is received outside the state, that income may qualify for the interstate and foreign commerce deduction. The sourcing rules for services are specific and differ from those for goods, so the full test matters. The DOR guidance on dor.wa.gov walks through the requirements. If you have clients in other states and have not looked at this deduction, it is worth a closer look before your next return.

Other deductions exist for certain casual and isolated sales, specific government-related activity, and industry-specific situations. Most service business owners never claim them because no one mentioned they existed when the owner originally registered.

The small business B&O credit

Washington offers a small business B&O credit that can reduce or eliminate liability entirely for businesses below a certain threshold. The credit phases out as revenue increases. Current credit amounts and the income levels at which they phase out are at dor.wa.gov.

If your annual gross receipts are under roughly $250,000 and you have a single activity type, the credit may reduce your liability. It covers the tax entirely on roughly the first $125,000 of income and phases out completely by about $250,000. Running a quick estimate before your next filing takes ten minutes and can reveal that you have been paying more than necessary.

Not filing is its own problem

Some service businesses skip B&O registration because they assume they are too small, outside Washington's reach, or in an exempt category. They are usually wrong on at least one of those assumptions.

Expecting to owe little or nothing after the small business credit is not the same as having no registration or filing requirement, and DOR's own guidance on dor.wa.gov is the place to confirm which applies to you. A business that has operated for several years without registering is not invisible. Business license records, contractor registrations, and third-party reporting tie back to DOR's database. DOR can assess back taxes plus interest and penalties on un-filed returns.

Washington's Voluntary Disclosure Program is available for businesses that have never registered. It can limit the lookback period and reduce penalties. Whether that is the right path depends on how much is owed and which years are at issue, but the unregistered business that waits for DOR to find it first has fewer options than the one that comes forward first.

When the B&O return is genuinely simple

A sole proprietor with one activity type, all clients in Washington, billing only time, and annual gross receipts comfortably below $250,000 may have a straightforward return.

The mistakes in this article tend to accumulate when a business has grown, added a second service line, started working with out-of-state clients, or brought on subcontractors without revisiting the original registration. If none of that describes your situation, the classification you started with may still be correct.

If it does apply, a review before the next filing is the lower-cost option.

Caro & Associates includes state and local B&O filings as part of the monthly accounting package. The tax services page covers what we handle on the tax side, and the pricing page shows what the full package costs. For contractors and trades specifically, this piece on accounting for Federal Way contractors goes deeper on the Retailing and Wholesaling classification and how the two differ in practice.

Questions owners ask about this

Does Washington B&O apply if my business was not profitable this year?

Yes. B&O is a gross receipts tax, which means it applies to total revenue before any deduction for costs or business expenses. A business that lost $50,000 on $400,000 in revenue still owes B&O on the full $400,000. The only deductions that reduce what is taxable are the specific B&O deductions DOR allows, such as certain interstate commerce receipts, not operating losses.

What is the difference between the Retailing and Service and Other Activities B&O classifications?

The rate and the sales tax obligation. Retailing applies when you sell tangible personal property or certain services directly to an end user. The current Retailing rate is 0.471 percent per Washington DOR, and businesses that file as Retailing generally must collect and remit retail sales tax. Service and Other Activities covers most professional service businesses and has had three tiered rates since October 1, 2025 per Washington DOR: 1.5 percent for prior-year taxable income subject to this classification under $1 million, 1.75 percent for $1 million to just under $5 million, and 2.1 percent for $5 million or more. The classification turns on what you actually do in each transaction, not your business license category.

Can I deduct out-of-state revenue from my Washington B&O return?

Potentially yes. If you perform services for clients located outside Washington and the benefit of those services is received outside the state, that income may qualify for the interstate and foreign commerce deduction. The sourcing rules for services differ from those for goods and are strict. The requirements and tests are on dor.wa.gov. If you have out-of-state clients and have not reviewed this deduction, it is worth checking.

What happens if I filed under the wrong B&O classification for several years?

If you overpaid, you can file amended returns and request a refund for years within the statute of limitations. If you underpaid, DOR can assess back taxes, interest, and penalties. Washington's Voluntary Disclosure Program is available for businesses that have not been filing at all; it can limit the lookback period and reduce penalties. The right path depends on how much is owed and which years are at issue.

My business does both consulting and product sales. Do I need two separate B&O filings?

One DOR account, but two separate lines on your return. Consulting income reports under Service and Other Activities; product sales report under Retailing, each at its own rate. If the product sales cross the retail sales tax threshold, that obligation applies to the product side only, not to your consulting work. DOR's online return has separate lines for each classification, which is often where business owners first realize they have been combining what should be separate.