Selling into Washington from outside the US? Caira by Unwildered can help organise sales reports, marketplace statements, invoices and tax questions before you register or reply to a buyer.
Washington Sales Tax, B&O And SaaS
Washington is important because of Amazon, Microsoft, cloud software, retail marketplaces and a tax system that includes both retail sales tax and B&O tax.
This guide is written for foreign founders, online sellers, SaaS teams, agencies, product brands and export managers. This guide does not replace a state tax adviser. It is meant to help you identify which information to collect before consulting a professional adviser.
Why This State Deserves Its Own Guide
Washington official guidance requires remote sellers to register if they meet the Washington receipts threshold, and the threshold can apply to combined gross receipts sourced or attributed to Washington. Official guidance also says some information technology, website and software development services became subject to retail sales tax from October 1, 2025. Sellers should review the latest Washington guidance to confirm current rules.
State tax questions can arise from common business activities, such as selling through marketplaces, attending trade shows, holding inventory in the US, signing enterprise clients or using a 3PL. Each state may treat these situations differently, so it is important to review the specific facts for that state.
The Five Checks
Situation | What to check |
|---|---|
SaaS or IT services | Check whether Washington's newer taxable-service rules apply to the exact service. |
Marketplace seller | Review sales tax and B&O tax separately; marketplace collection may not answer both. |
Direct e-commerce | Track Washington receipts, not just taxable product sales. |
Software development | Separate custom work, website work, support and platform access in invoices. |
US enterprise client | Prepare for tax and security questionnaires at the same time. |
What Caira Can Help Prepare
Caira by Unwildered uses AI to help businesses organise documents for easier review. For this topic, Caira can help you compare marketplace reports with direct sales, summarise customer-location data, extract key information from invoices or 3PL records, and prepare questions for your accountant, bookkeeper, customs broker or US client.
Caira should not be used as a substitute for regulated tax advice. Caira's value is in helping you prepare: more complete documentation, clearer questions and a better record of what has already been reviewed.
Documents To Put In One Folder
Washington receipts by activity;
Marketplace seller and facilitator reports;
Contracts and invoices for IT, SaaS or website services;
Product taxability notes;
B&O classification questions for an accountant;
Common Mistakes
Forgetting B&O tax while focusing only on sales tax;
Assuming marketplace tax collection answers service revenue;
Using pre-October 2025 digital-service assumptions;
Not separating implementation, support, hosting and software access;
These mistakes are easy to make because state sales tax does not feel like a product, shipping or contract issue at first. It becomes one when a marketplace report, buyer request, event receipt, warehouse record or customer address proves that the state has to be considered separately.
Short FAQ
If a marketplace collects tax, am I done?
Not always. Marketplace collection may help with marketplace sales, but you still need to check direct website sales, inventory, event sales, exempt sales and other taxes that may not be handled by the platform.
Does this apply if my company is outside the US?
In many cases, yes. State rules often focus on sales, delivery, inventory, marketplace activity or receipts, rather than only the place of incorporation.
Should I register in every state just in case?
In most situations, no. Registering in states where you do not have an obligation can create unnecessary filing duties. A better first step is to collect sales, channel, customer-location and inventory information, then consult a qualified adviser about which states require action.
What is a practical first step?
Separate marketplace sales from direct sales, identify where inventory sits, export sales by customer state, and keep proof of who collected tax. Then ask focused questions instead of sending a vague summary.
Sources Checked
Washington Department of Revenue Remote Sellers guidance.
Washington Department of Revenue Marketplace Sellers guidance.
Washington Department of Revenue Information Technology Services guidance.
Washington Department of Revenue Digital Products guidance.
This article is general information. It is not legal, tax, customs, financial or regulatory advice.
