بررسی تأثیر مالیات بر حقوق بر رشد اقتصادی ایران

Introduction: Taxes are one of the main sources of the government revenue. An important source of taxation is payrolls. In recent years, payroll tax revenues have accounted for a large share of tax revenues. Thus, one way in which the government can establish the superiority of tax revenues over oil revenues is through payroll taxes. Increasing the payroll tax rate, as the tax policy discussed in this paper, will have effects on economic variables that need to be studied. Economic growth is an important macroeconomic variable that indicate the economic development index of a country. In Iran, economic growth has always been the focus of governments and economic policy makers. So, in any development program, an indicator of development is economic growth. Therefore, this research seeks to examine the effect of increasing the payroll tax rate on Iran's economic growth.
Methodology: In this study, the Computable General Equilibrium (CGE) method is used to investigate the economic effects of implementing the payroll tax. In CGE model, the application of each policy in the model occurs by changing the exogenous parameters. In CGE model, the source of data is usually a matrix called the Social Accounting Matrix (SAM). A social accounting matrix is ​​a square matrix in which each account is located at the intersection of a row and a column. This matrix examines the numerical information of the economy comprehensively. Each currency represents the payment from the account on the column to the account on the row. The social accounting matrix shows the relationships between the main actors of each economy, including producers, factors of production, consumers, and institutions. There are also foreign actors in the form of classified accounts, including production account, factors of production account, institutions account, accumulation account (saving), and the account of the other world. The latest SAM of Iran is related to the year 2011, which was prepared by the Parliamentary Research Center. In this paper, it is used as a source of information. Based on above data, the model is calibrated to ensure the validity of the research. Then, the solution of the calibrated model is used as the basis equilibrium with which the results of the experimental test of the model are compared. Finally, the simulation of the policy of increasing the payroll tax rate is done in the research model, which includes several steps including the selection of  the policy parameter in the model (payroll tax rate), determination of the initial value of the policy parameter, calibration of the initial values, change of the policy parameter in the model (applying scenarios of 5%, 10% and 15% increase in the payroll tax rate), reimplementation of the model, determination of the new amount of endogenous variables (including economic growth), and  calculation of the percentage of changes in endogenous variables (analysis of the effects of higher payroll tax rates on economic growth). All the above operations are performed in the programming space of the GAMS software.
Results and Discussion: In the first step, by estimating the model and using SAM data, the parameters of the production and trade block of the research model, including substitution elasticity, share and transfer parameters in CES and CET functions, were obtained. In the next step, the simulation of research scenarios was done. It showed that increasing the payroll tax rate can reduce the supply of the factor of production and increase wages. Also, the effect of increasing the payroll tax rate on wages and employment is negative, but this effect is not significant. Increasing the payroll tax rate and reducing the level of employment reduce the gross domestic product (GDP) and the economic growth. Of course, like the change in the level of employment, the change in the economic growth is not as significant as the change in the payroll tax rate. Increasing the rate of payroll tax increases the government's tax revenues and, consequently, increases the total government revenue. So, by applying higher rates, the government revenue increases even more. The results of the sensitivity analysis showed that the research model is not very sensitive to different elasticities, and the differences are not significant. Therefore, the model is highly accurate, and one can rely on the results of the impacts of increasing the payroll tax rate on the economic growth and the other variables under the research model.
Conclusion: It is shown that increasing the payroll tax rate leads to increased wages and imperceptible reduction of the employment and economic growth. On the other hand, the positive economic effects of implementing this tax policy are an increase in tax revenues and government revenues. The policy makers' goal of increasing the payroll tax rate is mainly to increase government tax revenues and get rid of the oil economy. With regard to the heavier weight of the positive effects than the negative effects of the variables involved, it is concluded that the implementation of this policy as a whole can be beneficial for the Iranian economy if the increased revenues from the increase in the payroll tax rate are properly managed. The policy of whether or not to increase the payroll tax rate depends on the macroeconomic conditions of the country. In the current situation of Iran's economy, given the negative economic growth in recent years, on the one hand, and the realization of 100% tax revenues and even above the forecast, on the other hand, it seems that the government should postpone the implementation of the increase in the wage tax rate, so that the economy can recover in terms of production and achieve positive and continuous growth.