پژوهشنامه مالیات
سال بیست و پنجم شماره 83 (پاییز 1396)

Tax evasion is one of the ongoing challenges for any tax system, particularly for developing countries. The purpose of collection of value added taxes, based on its inherent characteristics of self control and capacity of tracking the transactions chain, is the gradual clarification of economical transactions, and also built-up of a new source of income that is sustainable and reliable for financing the government’s budget. Furthermore, it is necessary that such clarification or transactions among the traders be dominant since the first process of purchasing the raw materials up to the production and sale of goods, so as the tax may be rightfully collected.
The business Intelligence in general, and data mining in particular, are effective tools for enhancing effectiveness and efficiency in the assessment of tax evasion. In the present research, based on the available information on VAT taxpayers returns in the years of study (2009-2014), being audited by the tax administration, and data mining methods including, classification algorithms of Decision Tree, Naive Bayes, and K-Nearest Neighbor, and clustering algorithms of K-means and K-medoids, the tax evasions were predicted; then by applying the silhouette index the validation of results were performed, and in view of analysis on the tax indices of earned clusters, they were divided into low-risk and high-risk taxpayers. The results arising from applying the classification and clustering algorithms may assist the tax administration in planning for the assessment and prevention of tax evasion.

VAT Act has been implemented since 22 Sep. 2008, after approval of VAT Act by the Islamic Consultative Assembly and then by the Council of Guardians. In accordance with Article 85 of the Constitution of the Islamic Republic of Iran, this Act was originally implemented for five year on trial basis and that was to be re-assessed and after removal of executive and procedural problems, approved as permanent Act by the Islamic Consultative Assembly. In this paper, we will determine the VAT revenue gap in Iran, taking into consideration the capacity of this tax for application on goods and services with standard ratesing the macroeconomic method first, the potential basis of this tax system, based on the percentage of gross domestic product during the years 2008-2015, and then the potential (expected) income tax at the general rate and based on the statistical data available in the national accounts of the Central Bank of the Islamic Republic of Iran. In the next step, considering the amount of revenue collected by the Tax Administration of the country during the studies years, the VAT GAP computed at (31.43%) and the tax efficiency of this tax system in Iran during the studied years equaled 69% Calculation that represents a good performance of implementing this tax system in Iran.

For years, Economic scholars have been recommending independency of fiscal policies from oil revenues as a tool to stay safe from resources cures. Weather these recommendations is applied in oil exporter countries or not is the main question of this study. In other words, the aim of this paper is to investigate the independency of fiscal policies’ main instruments (including Taxes and government expenditures) from oil revenues fluctuations in oil exporter countries. To do this, we use of an unbalanced panel data for 21 oil exporter countries during 1980 to 2015. To cover some kind of heterogeneities in the panel we use Dumitrescu and Hurlin procedure to test causality relationships. Final results show that we can’t reject oil dependency hypothesis for this set of countries. Evidences show that oil is still main determinant of economic environments of these countries and fiscal policy instruments variations and business cycles are still the effects of oil cause.

The tax charge is based on profit for all units that have some sort of income, imposed by the government. Reduce the overall tax strategy defined financial disclosures, The goal of the present research is to investigate the relationship between financial constrains and aggressive tax strategy. To do so, a sample comprised of 82 firms enlisted in Tehran Stock Exchange for the period between 2003 and 2014 was investigated. The criteria used to measure aggressive tax strategy were the difference between accounting earnings, taxable earnings, and effective rate of cash tax. The research hypotheses were analyzed through using multiple variable regression models in the form of panel data. Also results showed that there has been a positive relationship between financial constrains and aggressive tax strategy. This means that when firms encounter financial constrains have more incentives to avoid tax payment to finance for financial resources compared to firms that have a better access to capital market.

The purpose of this study, is the study of influence of conservatism on relationship between operational cash flow and income taxed definitively accepted by the companies on the Tehran stock exchange. This research in terms of the objective applied research and in terms of the type of the exercise method, is a description- correlation and the type of solidarity – data, a little bit. In this research to collect data related to the research’s variables the audited financial statement has been used. The statistical community this research accepted all the companies on the Tehran stock exchange and to determine the samples of systematic removal method (388). For data analysis and correlation coefficients of test hypotheses, t statistics and regression by SPSS is used. finding, show the significant relationship between operational cash flow and definitive taxable income, and conservatism imoact on the relationship between operational cash flow and definitive taxable income.

Tax avoidance is activity that management uses his discretion to decline and earnings manipulation to reduce the tax payable And necessarily adoption this type of policy is not in the interests of all stakeholder groups. . The aim of this study is to Modeling the effect of the economic dimension of social responsibility on tax avoidance firms that are listed in the Tehran Stock Exchange.The period of Study is 1389 to 1393 and selected sample consists of 50 companies that were chosen by purposive. This research is an applied research and data analysis by using structural equation modeling. The results show that economic dimension has significant negative correlation with tax avoidance.

The main purpose of this study, the effect of factors related to confidentiality costs on the quality of financial reporting with an emphasis on tax avoidance in Iran. Factors related to the cost of the confidentiality include growth opportunities, profit margin, product market competition and concentration of ownership. The population of the firms listed in the Tehran Stock Exchange from 2008 to 2014 is the period of study. In this study multivariate linear regression was used to test the hypotheses. The results show that the factors related to confidentiality costs does not affect the quality of financial reporting. Also, tax avoidance does not effect on relationship between the factors related to confidentiality costs and quality of financial reporting.