Software interfaces purchased by a medical testing company are exempt from Utah sales and use tax because they qualify as custom computer software. In Utah, prewritten computer software is taxable and custom computer software is exempt as a sale of personal services. Prewritten software is not developed to a purchaser’s specifications. The software interfaces purchased by the company gave the company the ability to share information and communicate between its system and customers’ systems. The company used different systems than its customers, so different interfaces were developed to accommodate the individual programming language of each customer’s system. As a result, the software interfaces qualify as custom software and are therefore exempt from Utah sales and use tax. (Private Letter Ruling, Opinion No. 15-004, Utah State Tax Commission, September 28, 2015)