Washington’s Sourcing Rules & What They Mean for Your Business

Understanding Sourcing

Washington applies a destination-based sourcing model. This means sales tax is generally determined based on where the purchaser receives or first uses services.  

The Department of Revenue uses a hierarchy to determine sourcing for sales tax purposes. If a purchaser receives the services at the seller’s place of business, the sale is sourced from there. For example, a customer walks into a computer repair shop in Bellevue to have the laptop repaired there. This service is sourced to Bellevue.  

If the service is not received at the seller’s place of business, it is sourced to where the purchaser first uses the services, if such place is known to the seller. For instance, a Seattle marketing agency provides their client, a Bellevue company, with brand development services. The service is sourced to Bellevue because that is where the client first uses the service.  

If the location at which the services are first used is not known, the tax is sourced to the purchaser’s business address on record. As an example, if a Mercer Island design agency provides services to a client with multiple locations throughout the area and is not sure where the services will be used first, but records show the client’s principal place of business is Bellevue, then the sale is sourced to Bellevue.

If there is no address in available business records, then the sale is sourced to the address the seller obtains at the time of sale. For example, a business development consulting session is purchased online, if no other information is known by the consultant about the purchaser’s principal place of business, then the billing address used to purchase the consulting session should be used.   

Finally, if none of the above apply, a sale is sourced to where the seller performed the service.  For instance, a report is prepared on Mercer Island and the client’s location is unknown; the sale is sourced to Mercer Island.  

Common Pitfalls for Businesses 

These rules may seem straightforward, but businesses often trip up on some of these issues: 

• Assuming tax is based on where work is performed 
• Using billing address when a first use location is known  
• Overlooking remote services  
• Relying on outdated addresses  
• Not documenting sourcing determination  

Even small mistakes in sourcing can add up to significant exposure in an audit, especially when combined with Washington’s relatively high B&O tax rates. 

Practical Next Steps 

The safest way to handle sourcing is to build compliance into your operations before an audit comes knocking. This may mean adjusting contract language, strengthening internal accounting, or modeling the tax impact of how you deliver services or products. 

Talking with a tax professional or attorney who understands Washington’s sourcing rules will help ensure your business isn’t overpaying or inadvertently underreporting. 

Action Items to Consider:

      Map out where your customers actually use your services or products
      Revisit contract terms around delivery and usage
      Model tax outcomes under different sourcing scenarios
     Seek professional guidance before finalizing tax positions 

The rules may be complex, but the message is simple: sourcing determines whether your revenue is taxable in Washington. Getting it right now can save significant costs and headaches later.