The department grants approval to sales tax software companies for the e-file format XML (Extensible Markup Language). XML is similar to the Streamlined Sales Tax forms used by other states. If you represent a sales tax software company, your sales tax data in XML format must be tested and approved by the department prior to using it. For information on how to test this format and apply for approval, please see the Test Files below. If you have any questions, please email DOR_LocationFilers@state.co.us.