پژوهشنامه مالیات
سال بیست و چهارم شماره 77 (بهار 1395)

Tax fraud includes a large spectrum of methods including denying the facts and realities, claiming wrong information and performing financial businesses without considering legal frameworks. Nowadays, with the development of tax systems and the large volume of tax data, it is necessary to have tools to process this large data and to exploit information and knowledge. According to tax policies, especially in value-added tax resource, the rate of tax fraud is increasing. Based on the investigations, researchers use standard methods such as association rules, clustering, neural networks, decision trees, Bayesian networks, regression and genetics to detect tax fraud. Because of large volume of tax database, most of the studied algorithms are time consuming. At first, Apriori Algorithm was used. This algorithm was one of the unsupervised learning models and association rules. It is used to detect suspicious behavior of tax fraudsters. Secondly, a system for tax fraud detection based on Bayesian networks is presented and its performance is improved using parallel processing techniques. Results of the study show that using available parallel processing patterns improve the execution time of tax fraud detection algorithm considerably.

Up to now in Iran's economy, a numerous tax bases have been identified with different rates. Here's the question that comes to mind is whether these rates are optimal. Is it possible to determine an average optimal rate in a way that would bring greater growth and prosperity? In the present study, weve been looking for Iran's optimal tax rate using time series data in the years 1978-2014 via a dynamic optimal control approach and the maximum principle. According to the findings, the optimal tax rate is 20%. And the main factors affecting tax rate are: the ratio of expenditures of the private sector to the public sector, the ratio of investment in the public sector to the private sector, depreciation rate, and rate of time preference, elasticity of production function to the investment in private sector and public sector and technical progress. Among the above factors, the ratio of expenditures of the private sector to the public sector has a negative effect and the ratio of Investment in the public sector to the private sector has a Positive effect on optimal tax rate.

Fiscal illusion influences situation of government budget. In this paper first, has been studied possible of asymmetry in government budget using Threshold Autoregressive (TAR) and Momentum Threshold Autoregressive (MTAR) models. Then is examined hypothesis of fiscal illusion in Iranian economy. In this regard, has been specified an Error Correction Model (ECM) via the indirect tax revenues seasonal data from during (1380- 1392 ) that the results from estimation of model show i) there is a negative casual relate on the indirect taxes to government expenditures with three lags. This finding emphasizes the existence of fiscal illusion in Iranian economy ii) is confirmed the asymmetry effect of indirect taxes on government expenditures as there is fiscal illusion in situation of reducing indirect tax iii) since indirect taxes compared to direct taxes are less observable, reducing indirect tax due to fiscal illusion and misperception of people the public services and goods price lead to increasing demand for goods and services of public. Therefore, reduction of tax cannot apply as efficient tools in order to decline of budget deficit.

The efficient VAT that does not distort the relative prices is the severely descending tax that has undesirable effects on income distribution and creates significant executive problems. The exemption is one of the tools for reduction of distributional and administrative consequences of VAT, but its overuse leads to more inefficiencies of this tax and as a result many benefits of the tax disappear. The purpose of this paper is to evaluate and review the exemptions granted in accordance with the VAT law, and it is investigating this issue that whether in designing VAT system the trade-off between efficiency goals, income distribution and ease of implementation has been considered?

Investigating tax policy making dealing with business cycles is the main goal of the present paper. To reach this purpose, two steps have been set up: at the first step, by analyzing the structure of tax policy in Iran's economy, priorities of policy makers have been identified. At the second step, the effectiveness of tax instruments in stabilizing (or destabilizing) business cycles has been determined. So that, despite of procyclical signs of tax rates in Iranian economy, they were not significant, statistically. So, to capture some stylized facts of Iran's economy, by employing "Fiscal Stance", instead of tax rates, it revealed that fiscal stance in Iranian economy is procyclical. Therefore, according to the global experience and existing theories, structural factors which could be effective in alleviating this procyclical space were captured. Among structural factors, the variables of production function meanwhile had a long-run relationship with the tax index, could be effective in stabilizing cycles. So, over recessions periods through protection methods, for instance, taxes must be used to keep the structural variables such as capital stock (K), and Labor (L) in a level which prevent from deep recession.

Today, planning for improving productivity is the successful key in all organizations. Because of the key roles of human resources in service organizations such as the Iranian tax organization, planning for improving labor productivity is more important. In this research, an index was identified to measure the productivity of tax labors and indicator variables were developed for measuring the factors that affect on labor productivity such as environmental, personal and organizational factors. The variations of productivity variable and other measured variables are studied to identify the relations between labor productivity and considered factors. The reliability and validity of variables are checked and the productivity and indicator variables for 108 labor of tax organization are measured. The Partial Least Square method is used to study the hypothesis of this research (the Impact of environmental, personal and organizational factors on labor productivity). The proposed model’s goodness of fit is probed by determination coefficient. This criterion is about 85 percent, which means more than 85 percent of variation of productivity variable defines by the proposed model. The statistical analysis shows that the three factors directly affect on labor productivity in the case study and the organizational factor is more important to improve the productivity.

In accordance with recent developments in globalization trend among nations, international tax law is incrementally approaching to the approved practices of world trade organization (WTO). Accordingly, nations resort to modification of their internal commercial law in a way to be more complied with principles set by WTO. In spite of insistence on justification of internal law and regulations to the rules of WTO in Iran’s fifth development plan, there are some discriminatory measurements, imposed on foreign-sourced goods, services and capital in direct tax law which needs to be amended in order to facilitate accession process for Iran. Examples of these discriminatory measurements in direct tax law are imposing different tax charges on similar activities adopted by local and non-local businesses as well as service contracts and intellectual property assignments.

The overall goal of this research is to identify and prioritize the factors affecting development of employee commitment to ethical behavior in order to improve and to explain the pattern of State Tax Administration in East Azerbaijan province. According to Lussier theory, commitment to ethical behavior and factors affecting on its development were defined as 43 factors by reading books, articles, previous research, and learn from experts. The research population is all employees of State Tax Administration in East Azerbaijan province, whose number is 849 people. The questionnaire gathered data, Lussier ethical behavior questionnaire and ethical behavior factors analysis is used to assess the reliability and validity of the sample analyzed. For statistical data analysis, descriptive and inferential statistical methods were used and finally a model for developing staff commitment to ethical behavior was designed.