Nowadays, electronic tax services provided by the government for taxpayers are the most important applications of e-governance. Apart from government’ s endeavor for supporting and providing necessary infrastructures, the adoption of e-taxation systems by taxpayers is inevitable. On this assumption, this study aims to explore the effects of factors derived from Social Cognitive Theory on adopting e-taxation systems. This is an applied research and from the viewpoint of methodology, it is a survey-analytical study. The statistical population consists of taxpayers of Khorasan Razavi Province Tax Directorate General. For the analysis of relations between variables in question, a structural equations method has been employed. The sample study has been estimated to include 300 subjects by a random sampling procedure. In order to gather the data, a questionnaire has been used. The empirical findings of the proposed model indicate that eight hypotheses have been confirmed with significant relations between the respective structural variables such that outcome expectation of e-taxation system affects the system and affects the adoption, social influence affects the adoption, self-efficacy affects the outcome expectation, outcome expectation affects the adoption through a mediating role of the effect and finally, self-efficacy affects the adoption through mediating role of the effect. However, it has been found out that there is no significant relationship between anxiety and the adoption in the seventh hypothesis. Abstract Nowadays, electronic tax services provided by the government for taxpayers are the most important applications of e-governance. Apart from government’ s endeavor for supporting and providing necessary infrastructures, the adoption of e-taxation systems by taxpayers is inevitable. On this assumption, this study aims to explore the effects of factors derived from Social Cognitive Theory on adopting e-taxation systems. This is an applied research and from the viewpoint of methodology, it is a survey-analytical study. The statistical population consists of taxpayers of Khorasan Razavi Province Tax Directorate General. For the analysis of relations between variables in question, a structural equations method has been employed. The sample study has been estimated to include 300 subjects by a random sampling procedure. In order to gather the data, a questionnaire has been used. The empirical findings of the proposed model indicate that eight hypotheses have been confirmed with significant relations between the respective structural variables such that outcome expectation of e-taxation system affects the system and affects the adoption, social influence affects the adoption, self-efficacy affects the outcome expectation, outcome expectation affects the adoption through a mediating role of the effect and finally, self-efficacy affects the adoption through mediating role of the effect. However, it has been found out that there is no significant relationship between anxiety and the adoption in the seventh hypothesis.