To calculate the Business and Occupation (B&O) tax in Washington, you work through four steps: classify each revenue stream by activity, determine which of those receipts are sourced to Washington, subtract any deductions and credits you qualify for, then multiply each remaining amount by the rate for its classification and add the results.1Washington Department of Revenue. Business and Occupation Tax B&O is a gross receipts tax, so the base is your total revenue before expenses or cost of goods sold. A single business can owe at several rates at once if it earns income from several types of activities.
Step 1: Classify Every Revenue Stream
Each dollar of gross receipts belongs to a B&O classification, and the classification sets the rate. The Department of Revenue (DOR) publishes a full schedule, but most businesses land in one of four buckets:2Washington Department of Revenue. Business and Occupation Tax Classifications
- Retailing (sales to consumers): 0.471%
- Wholesaling (sales to buyers who will resell): 0.484%
- Manufacturing (producing or processing goods for sale): 0.484%
- Service and Other Activities (professional services, consulting, anything without a lower-rate category): tiered, starting at 1.5%
Service Rate Tiers
The Service and Other Activities rate is not flat. As of October 2025, it rises with prior-year taxable service income:3Washington Department of Revenue. Service and Other Activities Rate Changes
- Less than $1 million: 1.5%
- $1 million to $4,999,999: 1.75%
- $5 million or more: 2.1%
The tier is based on last calendar year’s service income, not this year’s, so an $800,000 prior year keeps you at 1.5% for the whole current year even if you push past $1 million. Hospitals and certain advanced computing businesses stay at 1.5% regardless of size.
Specialized Classifications
Some activities have their own rates outside the four main categories. Insurance agents and brokers pay 0.484% on commissions. International investment management services and assisted living facilities pay 0.275%. Travel agents and tour operators pay 0.275% on the first $250,000 of income and 0.9% above that.2Washington Department of Revenue. Business and Occupation Tax Classifications If your business fits one of these, using it instead of the general Service rate changes the bill significantly.
When a Business Has More Than One Activity
A company that manufactures products and also sells them at retail earns income in two classifications and owes at two rates. You have to separate the revenue by activity in your books. If you don’t segregate it, the DOR can apply the highest applicable rate to the entire unsegregated amount. Construction contractors run into this constantly: the materials portion of a job is Retailing at 0.471% while the labor portion is Service and Other Activities at 1.5% or higher. Auditors check this split early.
Step 2: Figure Out Which Receipts Are Sourced to Washington
You owe B&O tax only on receipts that count as Washington income, and that depends first on whether your business has nexus with the state and second on how each type of income is sourced.
Do You Have Nexus?
Physical nexus is triggered by employees working in Washington, inventory stored in the state (including at a marketplace facilitator), rented property, delivering in your own vehicles, or sending representatives to solicit sales or install products.4Washington Department of Revenue. Physical Presence Nexus Even exhibiting at a Washington trade show can be enough.
Out-of-state businesses without any physical presence still owe B&O tax if they exceed $100,000 in cumulative Washington gross receipts in the current or prior calendar year.5Washington State Legislature. RCW 82.04.067 Substantial Nexus – Engaging in Business The threshold combines all Washington income across every classification.6Washington Department of Revenue. Out of State Businesses Reporting Thresholds and Nexus If you crossed it last year, you owe this year even if this year’s receipts drop below.
Sourcing Tangible Goods
Washington uses destination-based sourcing for tangible personal property. A sale is a Washington sale if the buyer receives the goods in the state, regardless of where the goods shipped from.7Washington State Legislature. WAC 458-20-145 Sourcing Retail Sales for Business and Occupation Tax A product shipped from a Seattle warehouse to an Oregon customer is not subject to Washington B&O.
Sourcing Services and Royalties
Service income uses market-based sourcing. You owe B&O tax on service revenue to the extent the customer receives the benefit of the work in Washington. If you consult for a company operating in five states and 30% of its operations are in Washington, roughly 30% of that consulting income is sourced here. You need a reasonable method for allocating the benefit and documentation of how you got there. Royalties and licensing fees follow the same logic, apportioned by where the intellectual property is actually used.
Getting this wrong is costly. If you can’t support your apportionment, the DOR can source the entire amount to Washington.
Step 3: Apply Deductions and Credits
Deductions reduce the taxable base within a classification before you multiply by the rate. Credits reduce the tax owed after the multiplication. Every deduction has to be claimed against the specific classification it applies to, and you need records supporting it.
Interstate Commerce
The most common deduction. For goods, deduct sales where the buyer received the product outside Washington. For services, deduct income where the benefit was received entirely outside the state. Documentation of destination or benefit location is required.
Amounts Received as Agent
If money passes through your business to a third party, you can deduct the pass-through portion and pay B&O only on your commission or fee.8Washington Department of Revenue. Deductions A travel agent, for example, deducts the airline’s share of a ticket and pays only on the retained commission. You need a written agreement or established industry practice showing the principal-agent relationship.
Bad Debts
Income you reported that later proved uncollectible can be deducted in the period you write it off, provided you also write it off for IRS purposes.8Washington Department of Revenue. Deductions If you later recover any of it, that recovery goes back into gross receipts.
Multiple Activities Tax Credit (MATC)
The MATC prevents you from paying B&O twice on the same product. If you manufacture goods in Washington and then sell them here, you would otherwise owe Manufacturing B&O on production and Retailing or Wholesaling B&O on the sale. The credit offsets one against the other.9Washington Department of Revenue. Multiple Activities Tax Credit (MATC) It also works externally, offsetting Washington B&O against a similar gross receipts tax paid to another state on the same product. The same person must be legally obligated to pay both taxes, both must actually be paid, and the credit cannot exceed your Washington liability.
Small Business B&O Tax Credit
This credit zeroes out or shrinks the B&O bill for low-liability businesses. The maximum depends on whether at least half of your taxable income falls under Service and Other Activities (including gambling and for-profit hospitals):10Washington State Legislature. RCW 82.04.4451 Credit Against Tax Due – Maximum Credit – Table
- Service-heavy businesses (50%+ service income): maximum annual credit of $1,920. If annual B&O tax is $1,920 or less, the credit wipes it out. The credit then shrinks and hits zero at $3,840.
- All other businesses: maximum annual credit of $660. Full offset up to $660, phasing out at $1,320.
The phase-out formula: reduced credit equals twice the maximum credit minus your tax due, floored at zero. A non-service business owing $1,000 gets a credit of (2 × $660) − $1,000 = $320, leaving $680 owed.
Step 4: Multiply, Add, and Subtract — A Worked Example
Take a business with $170,000 in gross receipts, all sourced to Washington after interstate deductions, split across three activities.
Classify and separate:
- $100,000 in consulting (Service and Other Activities)
- $50,000 in wholesale distribution (Wholesaling)
- $20,000 in direct-to-consumer sales (Retailing)
Multiply each by its rate. Prior-year service income was under $1 million, so 1.5% applies:
- Service: $100,000 × 0.015 = $1,500
- Wholesale: $50,000 × 0.00484 = $242
- Retail: $20,000 × 0.00471 = $94.20
Add: $1,500 + $242 + $94.20 = $1,836.20 in B&O tax before credits.
Apply the Small Business Credit. Service income is more than half the total, so the $1,920 maximum applies. Because $1,836.20 is under $1,920, the credit covers the whole bill. Tax owed: $0.10Washington State Legislature. RCW 82.04.4451 Credit Against Tax Due – Maximum Credit – Table
If consulting were $200,000 instead of $100,000, the service tax alone would be $3,000 and the total would rise to $3,336.20. The credit becomes (2 × $1,920) − $3,336.20 = $503.80, and the final tax is $2,832.40.
When You File and Pay
B&O is reported on the Combined Excise Tax Return, filed through the DOR’s My DOR portal.11Washington Department of Revenue. Combined Excise Tax Return – State Business and Occupation Tax The DOR assigns your filing frequency based on estimated annual liability:12Washington Department of Revenue. Filing Frequencies and Due Dates
- Annual, for liability of $1,050 or less. Due April 15.
- Quarterly, for liability between $1,051 and $4,800. Due the last day of the month following the quarter.
- Monthly, for liability above $4,800. Due the last day of the following month.
Some industries, including construction and restaurants, file quarterly at minimum regardless of liability. When a due date falls on a weekend or holiday, it moves to the next business day.
Penalties If You File or Pay Wrong
Penalties climb fast. A late payment on a timely return starts at 9% of the unpaid tax, rises to 19% after one month, and reaches 29% after two months, with a $5 minimum.13Legal Information Institute. WAC 458-20-228 Returns, Payments, Penalties, Extensions, Interest, Stays of Collection An audit assessment for substantial underpayment carries its own penalty: 5% when the assessment is issued, 15% if unpaid by the due date, and 25% if unpaid 30 days after that. Operating without registration adds another 5% on all unpaid tax.
Interest runs on top of penalties from the original due date. The assessment interest rate for 2026 is 6%.14Washington Department of Revenue. Interest Rate Tables
Don’t Forget City B&O Taxes
The state calculation isn’t always the whole picture. A number of Washington cities, including Seattle, Bellevue, Tacoma, and (starting in 2026) Vancouver, impose their own B&O taxes with separate rates, classifications, and returns. Cities administer these directly, not the state DOR, so you register, file, and pay locally. If your business operates in or generates revenue from one of those cities, check that city’s finance department for its rates and requirements before assuming the state return covers you.