Electronic government (e-government) investments are made to help governments transform service delivery in a way that they fulfill their obligations to stakeholders in the most efficient and cost effective way. During this process, governments are under constant pressure to deliver better public services with fewer resources which necessitate the use of confidential evaluation methods for IT investments in e-government in order to guide policy and decision makers and to raise public approval. Despite a various number of evaluation methods, there is still lack of an appropriate method, which takes all perspectives and dimensions into account. The aim of this paper is to investigate the existing state of art dealing with the principle approaches of evaluation of e-government investments by following a comprehensive review of the normative literature and contributing to these works by suggesting guidelines for developing an appropriate model.