The main purpose of this book is to study the macroeconomic and welfare effects of the social security system in Iran. Iranian social security system is fragmented in different schemes, out of which, I focus on two major schemes related to the two main pension organizations, i.e., SSO and CSRO. These two pension systems have not only different mandates but also are governed by different rules and regulations. Moreover, due to the demographic changes, institutional draw- back, early retirement, reduced number of contributors and growing liabilities, that brings about the current system in the verge of collapse. These points are compelling reasons for a comprehensive reform in the Iranian pension system. Furthermore, in order to have a clear understanding of the reform, it is required to become acquainted with the Iranian tax system. Hence,I also studied the tax reform in Iran.