The advancement of information technology has changed the way of performing all activities and the use of the Internet in the economy and business, especially in the banking industry, has grown significantly. One of its important achievements is electronic banking. The electronic banking industry plays a significant role in improving the performance of the country's tax system. Using electronic transactions of banks in the tax system can increase transparency, reduce tax evasion, increase the supervision of tax officials, increase efficiency, and reduce executive costs. Examining the effect of electronic exchanges on the creation and strengthening of social trust in the tax system seems to be very necessary. Therefore, according to the importance of the subject, this research seeks to design and explain the social trust model in the country's tax system, relying on B2B electronic transaction mechanisms in the banking system (Sepah Bank's case study). In the first phase of qualitative research, to find the primary categories and design the primary model or framework, by applying the case study strategy and collecting information through structured interviews, and by applying Thematic Analysis method, the research model is designed. In the second phase, to explain the social trust model in the country's tax system, relying on B2B electronic transaction mechanisms in the banking system, questionnaires and data analysis using Delphi methods are used.