This book is focusing on analyzing current challenges in E-Taxation system as a part of the E-Government initiatives. Governments worldwide have been making significant attempts to make their e-tax filing services available on the Internet. However, despite the apparent benefits as online services’ immediacy and saving costs, the rate of adoption of E-Taxation is globally below experts’ expectations. The consolidated analysis of E-Taxation models has revealed similar problems in this area – lack of trust and its negative effect on level of E-Taxation adoption. This book is drawing relationship between trust of citizens’ and security of E-Taxation transactions which is directly affects their willingness to use online tax filing services.