Journal of Tax Research

---

Being aware of the determinants of tax capacity and the potential ability of the country to make use of this capacity is the key for any plans to increase tax revenues. In this article, a new specific definition of economic capacity of taxation has been given and on the basis of the information gathered from 20 different countries within the period 1998-2006, the Iranian potential economic capacity of taxation has been estimated within the framework of panel data model. The results of the study show that the average economic capacity of taxes in Iran (excluding social security contributions) has been about 12.33 percent during the period in question. Therefore, it can be concluded that the actual performance of the country (7.1 percent) during the mentioned period has been quite low. In addition, the results of the study show that the tax effort index in Iran has been about 58 percent during the period under study.

---

The present research aims at estimating and forecasting tax revenues of Ghazvin province up to the year 1393/2014 on the basis of data of the years 1374/1995-1383/2004. Researchers have tried out to identify the potential/realized tax capacities of the aforesaid province and to explore how to decrease the gaps between the existing and ideal capacities. They have also dealt with identifying the shortcomings of the tax system in the province in question and in the whole country. Research findings show that in spite of a large variety of endogenous variables involved, the general trend of estimation fluctuations has been in conformity with the fluctuations of tax performances of different years so as to say that any abrupt improvements in the tax performance of the province in question have been reflected in the predictions thereof.

---

The paper explores the trends of increases in taxes as part of the government revenues and focuses on the T/GDP ratios in Lorestan province. Lorestan tax capacity and the factors influencing it during the period 1360/1981-1383/2004 have been estimated through ARDL econometric method. On the basis of existing theoretical discussions and experimental works previously done on the topic, some endogenous variables such as the value-added of different economic sectors, per capita income, rate of literacy, rate of inflation, and population have been regarded as the most important factors affecting the tax capacity of the province in question. The results indicate that there is a positive correlation between the tax capacity, on one hand, and the value-added of the sectors industry and services, and the rate of literacy, on the other hand. However, there is no significant correlation between the tax capacity and the variables of the value-added of the mines sector, the per capita income, the rate of inflation, and the population. In addition, the tax capacity and tax effort of Lortestan province have been calculated on the basis of the estimated parameters of the model during the period under discussion. A comparison between the collected taxes and the estimated tax capacities shows that the Lorestan tax administration has not been highly efficient in the period under investigation.

---

Taxes have been the most significant income sources of governments from a long time ago and one of the main concerns of governors and policymakers is optimal collecting taxes of whole existing capacities.The aim of this paper is to estimate tax capacity and to calculate tax effort among middle- income countries. Panel data method, data from 1995-2009 and Stata software have been used to estimate model coefficients and then tax effort has been measured by using these coefficients. The results show that Iran obtains the least amount of tax effort indicator among others.

---

According to the great importance of the tax incomes in supplying the governments’ necessary financial resources, governments and politicians have always taken heed of considering the potential capacity of the taxes. In this paper, the tax capacity function is estimated by utilizing both the Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) Algorithm from 1361 to 1389. According to the performance evaluation criteria, the estimated model with the PSO algorithm is selected to assess the tax capacity. The results of the estimated model demonstrate the positive effects of variables of the income per capita, the value added of the industry, mine and services sections to the gross domestic product rate on the tax capacity. Besides, the value added of the agriculture section to gross domestic product rate, inflation rate and unemployment are linked to the tax capacity in a reciprocal relation.

---

The main purpose of this paper is, to design a dynamic model for evaluation of economic and tax policies on Iranian tax system by using system dynamics approach. For this purpose, we consider the tax effort, tax capacity and tax evasion subsystems. The simulation of this model has been accomplished during 2008-2025. The results of base model simulation show that, if current situation continues, situation of tax effort and tax evasion will not in good position and in 2025, only 66 percent of expected tax will be collected. Also the extent of tax evasion in years of the final simulation will be 35 percent. For study of necessary conditions in order to access to optimal status, different scenarios have been designed and simulated. The results of simulations show that, in order to access to the desired status, in addition to coordination and interaction among the variables, some attempts should be done simultaneously to reduce the inflation rate, increase welfare, and decrease the activities in underground economy, increase population growth, per capita revenue and taxes (taxes on consumption and import).

---

Regarding the importance of tax revenues in funding the government expenditure, estimation of the tax capacity can play a major role in economic policies. Therefore, in this study, the estimation of economic tax capacity is reviewed in the provinces of the country during the period of 1380 – 1390 (2001-2011), the tax capacity of the taxes share of the provincial gross domestic product is defined, and spatial econometrics method is used for estimating the economic tax capacity. The results show that increase in the Human Development Index (HDI) results in the increase of income tax, sales tax, wealth tax, and total tax, and also show that the share of agricultural sector added value from total added value is indirectly effective on tax capacity. Also, increase in the share of industry and mining sector added value from total added value leads to increase in income tax and total tax, while increase in added value is not positively effective on sales tax and wealth tax.

---

Abstract 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.

---

 The present study focuses on the lack of existence of internal and external studies in identifying the role of various dimensions of e-commerce tax capacity model design and online sales tax studies, especially in avoiding performance taxes in Tehran Province Tax Affairs General Directorate. The statistical population was all of the experts and managers. In qualitative phase, purposeful sampling has been used which is also called non-probability, purposeful or qualitative sampling. So, the views of 11 experts and managers have been gathered. In quantitative phase, 180 employees were considered as available sample. The data collection methods are consisting two categories: library and field. Regarding the collection of information related to the literature on the subject and research background, library methods have been used and in order to collect information to confirm or reject the research hypotheses, the field method has been used. interviews and three types questionnaires were used to collect data. In the first study, the data analysis method, after collecting information from content analysis, will try to analyze and interpret the results and implement a qualitative model. In the second study, using a descriptive survey method, the structural-interpretive modeling method has been used. The qualitative data analysis was performed by theme analysis method. The MAXQDA software was used for qualitative content analysis. The structural equation modeling has also been done with SMARTPLS software.

---

The present study has identified the dimensions and explored the structural relationships of the indicators affecting the tax capacity of e-commerce and internet sales tax in avoiding the performance tax in Tehran Tax Affairs Organization. The statistical population in the present study is a collection of experts and managers of Tehran Tax Affairs Organization, which was used from the point of view of its twelve experts and managers by using targeted sampling. Regarding the collection of information to confirm or reject the research hypotheses, the field method has been done through interviews and questionnaires. The method of data analysis will be tried after collecting information from content analysis, analyzing and interpreting the results and implementing the qualitative model. In the second study, where the descriptive survey method was used, the structural-interpretive modeling method will be used. Qualitative data analysis in this study was done by theme analysis method using MAXQDA software.