Previous studies have determined that information technology dominates numerous e-government projects; information and communications technology has been used mainly as a tool for enhancing the efficiency and service delivery of governments. Electronic government(e-government) should achieve public innovation goals, such as redesigning information relationships among stakeholders, enhancing citizen participation in the policymaking process, and reinforcing policy enforcement to create public value. These goals are more valuable, but also more complex, than the digitization of existing governmental processes. Therefore, this study focused on a crucial e-government service, the Taiwan taxation service, to determine whether, in the current era in which people depend highly on network tools to send and receive information, online services are suitable for taxpayers and how to improve the service process. In this study, service design tools were combined with a qualitative research method, and observation and individual interviews of participants were conducted to record their perceptions of the tax service process. The results of the study facilitate identifying gaps in the seemingly convenient and progressive tax service process of Taiwan, including insufficient information provision, complex website operation, inconsistent information classification with users’ logic, the lack of complete and consistent service for one-stop windows, and difficult document content. The taxation authority should integrate all online taxation services to achieve the expected public service (one-stop e-government window). This research facilitates relevant government agencies to provide effective e-government services, identify problems, and modify service delivery processes.