Washington Sales Tax Calculator

The calculation itself

Washington levies 6.5% at state level with local rates on top, taking combined rates above 10% in parts of the state. Sourcing is destination-based, so the rate follows the delivery address.

The complication is that sales tax is not the only tax on the transaction. Washington also levies a business and occupation tax on gross receipts, which the seller pays out of its own revenue rather than collecting from the customer.

Running the numbers

A $58 order at a 10.1% combined rate: $5.86 of sales tax, collected from the customer.

Then the B&O tax. At the retailing classification rate of 0.471%, the $58 sale attracts $0.27 of B&O, paid by the business, with no deduction for cost of goods.

On $580,000 of Washington retail revenue that is $2,732 of B&O tax on gross receipts, regardless of whether the business made a profit. For a low-margin operation that is a material cost that has no equivalent in most other states.

What gets missed

B&O is a gross receipts tax, not an income tax. There is no deduction for cost of goods, wages, or any other expense, which means a business operating at a loss still owes it.

Rates differ by classification: retailing, wholesaling, service and others, and a business with multiple activities pays different rates on different revenue streams, reported separately.

What to do next

Model B&O alongside sales tax when evaluating Washington. Sales tax is collected from customers and passes through; B&O comes out of margin and is easy to omit from a market-entry calculation entirely.

Then classify revenue correctly across B&O categories. Reporting everything under one classification is simpler and frequently wrong, in either direction.

Nexus for B&O is not the same as for sales tax

Economic nexus for sales tax follows the familiar $100,000 threshold. B&O nexus has its own rules and its own thresholds, and a business can have one obligation without the other.

That means a seller can conclude correctly that it has no sales tax obligation in Washington while having a B&O filing requirement, or register for sales tax and overlook B&O entirely. The two are administered together and determined separately.

For any business with meaningful Washington revenue, the practical step is to check both tests explicitly rather than treating the sales tax determination as covering the question. B&O assessments on unregistered sellers carry the same penalties and interest as any other, and the tax base being gross receipts means the amounts can be larger than the profit on the sales that generated them.

The small business credit reduces or eliminates the liability at low revenue levels, and the threshold at which it phases out is low enough that most established sellers are past it.

There is also a deduction for interstate sales in some classifications, which means correctly identifying where a sale is sourced matters for B&O as well as for sales tax, and the two use different rules.

For a business with substantial Washington activity, having the classifications and deductions reviewed once by someone familiar with the tax is worth considerably more than working it out from the forms.