On September 26, 2018, the Illinois Department of Revenue issued a Private Letter Ruling confirming that certain electronic signatures satisfied the first prong of the software license sales tax exemption test. In Illinois, a license of software is not a taxable retail sale if a five-part test is satisfied. The first prong asks whether the license is evidenced by a written agreement signed by the licensor and the customer. The Department had previously concluded that a license agreement in which the customer electronically accepts the terms by clicking “I agree” does not comply with the requirement. Here, the Department concluded that four methods of executing the Order Form satisfied the written agreement prong: (1) physically signing the Order Form; (2) physically signing the Order Form and then digitizing the Order Form into a PDF file; (3) using DocuSign to sign the Order Form; and (4) digitally signing the Order Form by pasting a digital image of a signature onto the PDF Order Form file and then saving the file with the signature image embedded into the Order Form. However, the Department did not have sufficient information to determine whether the use of a competing software product satisfied the prong. Additionally, the Department concluded that it would incorporate the Terms and Conditions Agreement into the Order Form in order to constitute a written agreement.