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Sales of custom software and customization of prewritten software

Starting Oct. 1, 2025, sales of custom software and the customization of prewritten software (regardless of the method of delivery to the end user) are subject to Washington retail sales tax. If you sell these services in Washington, you must collect and submit sales tax. These services include:

  • Charges to consumers for the right to access and use custom software, and customization of prewritten computer software, where possession of the software is maintained by the seller or a third party, regardless of whether the charge for the service is on a per use, per user, per license, subscription, or some other basis.
  • The right to access and use custom software, and customization of prewritten computer software to perform data processing.

Note: Unmodified “off-the-shelf” software is not included.

For detailed scenarios and examples, review our Custom Software and Customization of Prewritten Software Interim Guidance.