The main purpose of this paper is to investigate the impact of oil REVENUES on oil-exporting countries’ TAX REVENUES. To do this, countries have been divided into two group including low and high level, in terms of the degree of trade openness, and the considered model has been estimated by using countries panel data during 1998 to 2014. The results show that oil REVENUES have had a significant negative impact on TAX REVENUES, in both groups of the mentioned countries. In addition, the other variables don’t have any significant impact on TAX REVENUES in countries with low degree of trade openness, while they (except GDP) have significant positive impacts on TAX REVENUES in countries with high degree of trade openness.

Purpose: The oil revenue is considered a key variable in economic policies, which has always been in the focus of politicians and economists as a key variable in developing economies. Oil revenue fluctuations are one of the limitations of economic growth and cause the withdrawal of resources from the economic cycle. Their allocation to activities with low productivity and efficiency reduces economic growth. In countries with an environment of low institutional quality, oil revenue fluctuations can encourage rent-seeking activities. This is especially true in less developed countries with a large public sector, inadequate management, and complex and inefficient TAX systems. In Iran, due to the relatively large and inefficient public sector, low institutional levels, and rich natural resources, rent-seeking is rather prevalent. According to this discussion, the purpose of this study is to investigate the effect of oil REVENUES on TAX REVENUES under conditions of TAX rent-seeking. To this end, the dynamic stochastic general equilibrium model (DSGE) is used to examine the period of 1991-2020. Rent seeking is the competition of individuals and the government for financial privileges. This competition is for subsidies, higher income transfers, and lower TAXes. Therefore, the available resources are allocated to rent-seeking instead of productive activities. Among economic variables, oil REVENUES are a key indicator affecting macroeconomic performance. Until now, there has been no study on the effects of oil REVENUES on TAX REVENUES under conditions of TAX rent-seeking, as one of the country's economic challenges. The aim of the present study is to investigate this issue.Methodology: The purpose of this research is to model Iran's economy under conditions of rent-seeking and increased oil REVENUES. In order to evaluate the effects of oil REVENUES on TAX REVENUES, the general stochastic dynamic model was applied. The overall structure of the model designed in current research includes five main sectors: households, firms, oil, government, and the central bank. It resulted in 22 equations with 22 unknown variables. The employed data are the seasonal data of Iran’s economy for the period of 1991-2020 provided by the time series bank information of Iranian’s Central Bank and the Iranian Statistical Centre. After linearizing the model equations, the coefficients of the model were calculated using the quantification method. Then, the designed model was run in the Dynare software, and the instantaneous feedback results related to the shock of oil REVENUES were obtained.Findings and discussion: The results indicate that an increase in the oil REVENUES initially leads to an increase in prices, imports and government's TAX REVENUES, but, later on, due to the increase in the price and the decrease in purchasing power, the motivation of people for TAX rent-seeking increases, and part of the TAX REVENUES are not realized. This is consistent with both the theoretical foundations of the economy and the observed evidence in the country. However, the realization of oil REVENUES reduces the motivation of the government to create a precise TAX system, and the government makes less effort to establish optimal TAX systems and realize TAX REVENUES, which leads to an increase in the motivation to TAX REVENUES rent-seeking. In other words, TAX evasion rises. Therefore, the motivation of households to reduce working hours and rent-seeking from the government's TAX REVENUES increases. A part of the TAX REVENUES, enters the household budget rather than the government budget, and the force labour devotes part of its productive working hours to non-productive work (rent-seeking).Conclusions and policy implications: Furthermore, an increase in the oil REVENUES leads to decreased government's TAX REVENUES under conditions of TAX rent-seeking. Consequently, households are motivated to reduce the working hours, and rent-seeking from TAX REVENUES increases. In Iran's economy, the TAX system has been reformed over the past years, but, due to structural problems that are rooted in economic, cultural and political factors, the TAX system is not efficient. A part of the TAX REVENUES is included in the household budget instead of the government budget. Since, the reduction of rent-seeking leads to the increase of productive activities, it is suggested that economic policy makers formulate TAX systems so as to limit the space for earning rent in the country. Through increasing productive activities, reducing transaction costs, improving productivity, increasing investment, and ensuring greater transparency and stability of monetary and financial policies, the government can play an important role in the institutional quality of the society and thus reduce the tendency of people for rent-seeking.

One of the goals of the fourth and fifth Iranian development plans is to reduce the dependency on oil REVENUES and replacing TAX REVENUES would be the best alternative in this regard. The present study is examining the relationship between TAX REVENUES share and other government’s REVENUES (including oil REVENUES) shares in Iran during 1978-2014 (1357-1394 corresponding to Iranian calendar). For this purpose, the net effect of applying a combined shock including increasing one-unit in TAX revenue along with decreasing one-unit in oil REVENUES is studied on TAX REVENUES, oil REVENUES, budget deficit and the price index; by estimating a system of simultaneous equations and using Vector Autoregressive method (VAR). The results indicate that the initial instability effects of the mentioned shock are removed within 8 to 10 periods. Therefore, can be declared that there is a possibility of replacing oil REVENUES by TAX REVENUES, without undesirable impact on the considered variables’ long-term conditions.

TAXes constitute the main sources of government revenue on one hand and, on the other hand, are one of the most important financial policy tools and can play a key role in economic growth and development. Therefore, it is important to identify TAX payment potential as a step towards achieving these REVENUES. However, part of the TAX revenue cannot be collected for legal and illegal reasons. In other words, this part of TAXes may be lost (TAX expenses). The purpose of the present study is to investigate the effect of these lost income (TAX expenditures) on Iran's economic growth. For this purpose, the period of 2009-2012 was used as a sample data for a simulation to predict this TAX expenditure, which the country is still suffering. To this end, the Randomized Bayezian Coefficients are applied. The findings indicate that the estimation of TAX expenditure in the economy is different from one period to another period. However, the impact of TAX expenditures on growth is low and also negative. The greatest impact on growth was in 2010.

Forecasting TAX REVENUES is vitally important issue for optimal allocation of TAXable resources, planning and budgeting in national and regional levels and knowing the potential national participation in public expenditures. The classical optimization based on mathematical methods may not be reliable in real world and mostly inefficient and inapplicable in complicated world due to their restricted assumptions. The smart optimization may help us to find the solution.This essay based on modified PSO methodology. The initial trial based on the data during 1971- 2007 in case of various direct and indirect TAXes, and using updated data during 2008- 2012 for final forecasting, to estimate TAX REVENUES for upcoming next three years (2013 up to 2016) by MATLAB software.

In this article, the impact of income inequality (measured by both the Gini coefficient and the share of the ( top) wealthiest ten percent to the poorest ten percent) on TAX structure in Iran in the period of 1978-2020 by using the ARDL model is investigated. The results showed that both in the short and long term, income inequality (both measures of income inequality) has increased the ratio of indirect TAXes to GDP. While its impact on the direct TAX ratio was negative. Therefore, income inequality leads to the turning of the TAX capacity from direct TAXes to indirect TAXes. Therefore, the TAX system in Iran has not been progressive and relies on indirect TAXes. This result can be justified by the structure of Iran's economy, which is not easy to collect direct TAXes due to the underground economy and TAX evasion and the government is relying on indirect TAXes to earn income.

Budget plays an important role in public sector management and administration .one of its components is REVENUES forecasting and Without the necessary accuracy in predicting REVENUES, government deficit will occur and people are incapable of facing with losses of reducing of important and essential services like education and health care. In this study, the rational expectations hypothesis is a matter of predict the government TAX REVENUES. The models are estimated by OLS method show that between TAX REVENUES only for the TAX on legal entities that can not weak rationality hypothesis rejected. Also, the strong rationality test results to the model by using SURE estimation, suggests that strong rationality hypothesis is confirmed for forecast revenue from TAXes on legal entities. This means that planners predict budget of income TAX on legal entities unbiased and rational by using available information efficient.

The expansion of government interventions in economic & social circumstances, as well as increasing trend of its liabilities in favor of economic growth, price stability, employment and fair income redistribution, have faced government with a boom of expenditures. TAX REVENUES in developed countries are of substantial importance in financing government expenditures, while in developing countries such problems as dominance of inflationary structure in economy and inefficiency of TAX systems have caused TAX REVENUES to be a trivial percentage of GDP.In Iran, TAX REVENUES, after oil REVENUES, are in the second place in government budget which persues three goals of optimal resource allocation, income redistribution, and economic stapility. Following what was mentioned above, in this survey, the long run and short run relations of TAX REVENUES and macro variables, effective on the level of TAX REVENUES (for the period 1338-80), have been examined by utilizing co-integration method.

This quantitative research was conducted with a positivist paradigm to evaluate the methods that could increase TAX REVENUES from government REVENUES using oil dependency reduction. The researcher used the annual data of Iran during 1978-2019 to analyze the research model. In addition, a generalized torque technique was applied in the EViews software to estimate the model. According to the results, the variable of oil REVENUES had the most significant effect on the government REVENUES, followed by the revenue of sales and consumption TAX and value-added TAX (VAT), indicating that the government could easily reduce oil REVENUES by efficient policies and replace this source of income with the revenue from sales and consumption TAX and VAT. On the other hand, the revenue from wealth TAX had the least significant impact on the government REVENUES, which was possibly caused by the inefficiency of reception methods or the inability to be identified. Further assessment in this regard could help governments identify extremely more appropriate revenue resources to extract less oil and control social inequity. An important issue observed in this study was the reverse coefficient of the revenue from corporate TAX. Most of these companies may be manufacturing and industrial units, and given the pressure of economic and political issues and inflation on the country, they have mostly reacted to enormous TAXes, had TAX evasion, or reduced their production level, which has, in turn, increased the rate of unemployment and decreased the national gross domestic product, thereby reducing the government REVENUES.