More businesses will be subject to Washington state’s sales tax beginning Oct. 1, and state officials are working to make sure they are fully aware of it ahead of time. 

The Department of Revenue is sending letters and digital alerts notifying tens of thousands of business owners of a possible change in their tax reporting requirements after the Legislature changed what business services will now be defined as retail sales, according to a release.  

Revenue anticipates the new law, ESSB 5814, will affect more than 90,000 businesses.  

Among those business services that will now be charged a retail sales tax are: 

• Information technology services. 
• Custom website development services. 
• Investigation, security, and armored car services. 
• Temporary staffing services. 
• Advertising services. 
• Live presentations. 
• Sales of custom software and customization of prewritten software. 
• Modification of digital automated services exclusions. 

Owners of businesses providing those services are encouraged to learn more about the tax changes prior to the Oct. 1 start date.