The purpose of this research is to explain and validate the EFFECTIVE factors in the TAX audit quality improvement MODEL. Since an important part of each country's macro decision-making is budget information and its related resources, and also a major part of social inequalities is caused by the lack of transparency in incomes and income gap, therefore identifying the factors that improve the quality MODEL of TAX audit And the evaluation of their relations can be a step in the direction of helping to fully secure the spending credits of the government's general budget, providing and increasing stable incomes, promoting TAX justice and improving the structure of income distribution, helping the country's growth and development and realizing social justice. . The current research is an applied research. The data collection for the process of testing the designed MODEL was done through a questionnaire and according to the categories obtained from the subsets of the main categories, and to measure the validity of the designed MODEL from the structural equation MODEL (analysis of quantitative data through confirmatory factor analysis ) and to test the hypotheses, PLS and SPSS software were used to analyze the correlation between variables and other tests. The findings of the research showed that the causal factors affecting the improvement of the TAX audit quality MODEL have a positive and significant effect on the central phenomenon categories affecting the improvement of the TAX audit quality MODEL. Also, the findings showed that the categories of the central phenomenon, background and intervening factors EFFECTIVE on the improvement of the TAX audit quality MODEL have a positive and significant effect on the strategic factors EFFECTIVE on the improvement of the TAX audit quality MODEL. Also, the findings showed that strategic factors have a positive and significant effect on the results.

Objective: This study investigated the effect of EFFECTIVE TAX rates and the quality of corporate governance on TAX evasion and corruption by using financial variables. Methods: Multiple regression MODEL was used to examine research hypothesis. Data was selected by referring to the financial statements and explanatory notes of the companies listed on Tehran stock exchange, and a sample containing 1600 year-company entries for the period between 2003 to 2018 were selected. Data were analyzed by using Excel and Eviews software. Results: There is a significant positive relationship between the EFFECTIVE TAX rate and TAX evasion and corruption of companies listed on the stock exchange, but by adding the quality of corporate governance variable to the above relationships, no significant effect on the relationships between the EFFECTIVE TAX rate and TAX evasion and corruption was found. Conclusion: The findings of the research can be explained from two dimensions. The first dimension is the negative effect of corporate governance quality on TAX evasion and corruption, and the second dimension is the lack of effect of corporate governance quality on the relationship between EFFECTIVE TAX rate and TAX evasion and corruption. Given the fact that corporate governance quality is not fully developed in Iran and its current mechanisms and structures have not yet been implemented in a standard and comprehensive manner, its effect will reduce. Also, the size of the company based on the theory of political power, sales growth according to theory of TAX effect, and the rate of return on assets because of affecting the performance of companies, have a positive effect on TAX evasion. Changes in tangible fixed assets due to the difference between accounting profit and profit based on calculating higher or lower TAXes (depending on TAX laws and accounting applicable to property, machinery and equipment) also have a positive effect on TAX evasion, while tangible fixed assets have a negative effect on TAX evasion. Besides, fluctuations in sales and rate of return on assets positively affected TAX corruption, while sales growth, the ratio of market value to stock book, and the age of the company, based on life cycle theory, negatively affect TAX corruption.

According to economic researchers, TAX is the most appropriate and stable type of income for the government and an efficient tool for execution economic policies. Therefore, from their point of view, for the continuation of government activities, an efficient TAX system is necessary. One of the factors that is very important in establishing an accurate and EFFECTIVE TAX system, especially in developing countries, is the TAX behavior of TAXpayers. The purpose of this research is identifying EFFECTIVE factors on TAXpayer’s TAX behavior and the structure of relationships between them. For this purpose, mixed methodology is used. Factors have been identified by content analysis, the structure of relationships between them has been identified by interpretive structural MODELing, and they have been classified by MICMAC analysis. The results show that TAXpayers' financial behavior, transparency in TAX collection processes, TAX rates and coefficients, unions and trade associations, mass communication tools, TAX laws and regulations, the attitude of senior TAX managers towards TAX culture, designing and establishment a comprehensive TAX system and increasing people's awareness are the most important EFFECTIVE factors on TAXpayer’s TAX behavior

Just like other developing countries, in the recent decade, the importance and significance of TAXes in the Iranian economy has attracted the attention of economic researchers and that of policy makers. In the present paper, while I will focus on one of the most important aspects of TAX system, i.e. the whole set of incentives; EFFECTIVE TAX rates will be calculated and analyzed from a macro-economic standpoint. The most important issues are the efficiency of TAX incentive system and the working of EFFECTIVE rates. To do the task, I have simulated the time series in question and, by using Neo-classic Growth Theory and Jorgenson’s Theory on capital cost and defining the investment path, I have explored the impacts of investment cost and its components and the impacts of some other variables. The findings indicate that TAX exemptions do not work as incentives and do not have a considerable impact on investment. However, assets depreciation system may be used as an alternative TAX incentive to invoke investment.

Review of the public budget indicates the necessity of an increase in the share of TAX Revenues in the provision of Public Resources. Increasing TAXes influence Public Resources and Expenditures, GNP and Welfare. In this research, while a general equilibrium MODEL for analyzing Iran financial issues has been introduced, by using mentioned CGE MODEL through GAMS effects of increase in three main groups of TAXes including: Excises, Tariffs and Income TAXes, and also all these TAXes together (in form of three single scenarios and one combined scenario) on the economy, have been investigated. Reviewing results of single scenarios shows that the maximum effects occurred caused by 10 percent increase in EFFECTIVE excise rate, which raise public resources and expenditures 0/88 and 0/79 percent and decline budget deficit and welfare 14/04 and 1/58 percent. But, the best result overally obtained from the combined scenario with 19/74 percent fall in budget deficit due to 1/26 and 1/13 percent potential raise in public resources and expenditures along with only 0/14 percent decrease in welfare, which recommended as the preferred scenario for implementation. While, changes in GNP because of restricted TAX bases in all scenarios obtained negative and negligible.

The Hierarchy of EFFECTIVE Factors on Corporate TAX Avoidance Because of the information asymmetry within TAXpayers and governments, commonly, the TAXpayers try avoid the payment of TAX. The problem can be explained by Agency theory. On the other hand, governmants try to maximize receiving TAX by recognizing risky TAXpayers and researchers try to recognize EFFECTIVE factors on TAX avoidance. The aim of the research is the hierarchy of EFFECTIVE factors on corporate TAX avoidance on Tehran stock exchange. In this research, first, 37 quantity factors are recognized that affect on corporate TAX avoidance in 8 dimensions by interview with academic and professional experts that can be measure by corporate reports. Then the factors and dependent variable are measured and are tested the efficacy of the dimensions by structural equation MODEL (SEM). Finally, based on confirmed dimensions, hierarcy is done by contributed analytic hierarchy process quastionaries with same experts. Statistic population in this research involves 77 companies listed in Tehran Stock Exchange during the period 2013-2017 that are selected by systematic delete. The interview with experts done at 2017 and questionaries contributed at 2018. Results show that the hierarchy of EFFECTIVE factors on corporate TAX avoidance is: trading factors, corporate governance factors, auditor factors, financial reporting factors, industrial factors, public attributes, capital market factors and social factors.

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.