Determinacy of the Optimal Structure of Tax Revenues Based on Risk and Return

The existence of a stable source of income for the government is crucial for the financing of current and development expenditures. The major revenues of the government in Iran are derived from two sources of tax and oil revenues. Given that much of the oil revenue fluctuations are outside the control of domestic policymakers, it is better to focus on tax revenues in order to earn relatively stable revenues. However, tax revenues are also affected by cycles of boom and recession, and in terms of economic downturns, it is also difficult to earn money from this source. Thus, the solution for this problem is that the total tax revenue of the country is considered as a portfolio of income and applied to the methods of the financial economics to optimize it, in this way, an optimal combination Tax will be specified. Accordingly, in this study, by collecting information on different government revenues during the period of 1350-1396 and using the Markovitz model from two approaches to minimize risk and maximize returns, the optimal contribution of different tax bases for Iran has been calculated. The results show that the current share of the tax revenue base of the country is different from the optimal share.