In this paper, optimal TAX rates for real AND legal entity INCOME TAXes have been estimated. Optimal TAXation means optimal maximization of total utility functions of entities with regard to the budget constraint AND a constraint wherein the entities make their choices of labor supply taking into consideration the relationship between labor AND INCOME. The foundation of our estimation has been Diamond’s model (1998) which is itself an extended form of Diamond AND Myrrless’s model (1971). This model is, in its turn, an adaptation of Saez’s model, an important optimal TAXation model. The statistic population being used for the calculation includes real entities in Tehran AND legal entities in Tehran AND Kermanshah cities. In order to cover the fairness of INCOME distribution, the statistical data has been classified in terms of INCOME deciles, AND Gini coefficient was calculated as an indicator of INCOME distribution variance. Then, an appropriate model which is assumed to have the best impact on the decrease of the Gini coefficient has been selected. Finally, through the application of the selected model AND taking into account different levels labor force elasticity (for real entities) AND services supply elasticity (for legal entities), the optimal TAX rates have been calculated. The results obtained indicate that in the Iranian TAX system, the application of new rates would lead to a better distribution of INCOME as well as an increase of 150% in the government TAX revenues. Moreover, the calculated rates are able to be interpreted on the basis of an extended formulation of Laffer’s curve.

Estimating TAX capacity of a region or of the whole country provides the information needed for responding to financial AND executive problems resulted from the implementation of economic policies. The present study aims at estimating TAX capacities of the two TAX categories, “BUSINESS AND profession INCOME TAX” AND “corporate INCOME TAX” in the Iranian provinces through making use of the data of some effective variables. To this end, we have explored the variables involved in TAX revenues of the provinces, AND by using data of 28 different provinces within the time span 1379-1385 (2000-2006), we have resorted to SFA method to estimate the efficiency of each TAX category in question in any of the Iranian provinces. According to the findings obtained, as for the BUSINESS AND profession INCOME TAX, the average TAX efficiency of developed provinces (excluding Tehran Province) for the period in question has been 72.3% while it has been 66.5% in less developed provinces. AND as for corporate TAX INCOME, the average TAX efficiency of developed provinces (excluding Tehran Province) has been 47.8% while it has been 72.4% in less developed provinces. The present research has calculated the “TAX inefficiency” of each province as the gap between the potential AND realized legal capacities. As for TAX effort indices, the results show that over time, the average TAX effort has decreased for BUSINESS AND profession INCOME TAX but it has increased for corporate INCOME TAX.

Effective TAX rate is one of the most important TAX efficiency criteria in TAX literature. Moreover, TAX system efficiency is usually measured by bilateral comparison between administrative costs AND effective TAX rate. By examination AND estimation of effective TAX rate, TAX authorities are able to increase TAX justice AND investigate TAX burden on TAXpayers. Effective TAX rate could be an instrument to direct capitals, as well as its wide using in policy-making AND economic decisions. In present paper an attempt is made to estimate effective TAX rate in BUSINESS AND corporate INCOME TAX. The results show that effective corporate TAX rate had an increasing trend from 6.08 to 11.59 during 2001 to 2008 while effective BUSINESS TAX rate has been decreased by 2.1 to 1.3 between 2001 AND 2007.

Assessment of structural change circumstance of Iran's economic activities AND its effects on BUSINESS INCOME TAX is the major aim of present study. In literature of economic development, several methods have been proposed to measure structural changes, that among them "measuring change in production space based on international trade indices" method has been applied in this paper. Using mentioned method presents that the Iranian economy's production space occupied mainly by petroleum, chemical AND primary sector (agricultural AND raw material) goods AND any technological similarity (proximity) among exporting goods has not been seen. In addition, based on stochastic frontier model results, PROFESSIONS dependent into mentioned sectors had pour performance in TAX payment. In contrast, activities containing small density in production space had appropriate performance in TAX payment.

In this paper, to evaluate INCOME AND distributional effects of Personal INCOME TAX, a hypothetical society is simulated.12 INCOME sources are defined that each member of society can earn INCOME from one INCOME source or more. Then, using FORTRAN programming, the government's TAX INCOME, INCOME distribution AND average TAX rate are calculated, assuming five alternative Scenarios: 0. Base scenario: TAXing personal INCOME at source according to "Direct INCOME TAXes Act"; 1. TAXing the sum of INCOMEs each individual person earns from different BUSINESSes he or she owns AND exempt his / her BUSINESS INCOME once; 2. TAXing the sum of INCOMEs each person earns from non-exempt sources AND exempt his / her BUSINESS INCOME once; 3. TAXing the sum of INCOMEs each person earns from exempt AND non-exempt sources AND exempt his / her BUSINESS INCOME once; 4. qualifying third scenario by accepting a 1 billion Rials as exemption. Results of simulation indicate that the government's INCOME AND INCOME equality is maximized in 3rd scenario.

The present paper seeks to explore the factors involved in the difference between the TAXable INCOME declared by BUSINESS corporations AND the TAXable INCOME assessed by TAX authorities. To this end, data of BUSINESS corporations’ performance (data of the fiscal years 2005 AND 2006 being recorded in their statuary books) were gathered from TAX cases filed with West Tehran TAX Affairs Head Office AND, through making use of relevant statistical methods AND software, were put under investigation. The findings obtained indicate that there is a significant difference between the declared AND assessed TAXable INCOMEs. Moreover, the factors involved in this difference are all, in isolation, significant. In order to show the degree of importance of each factor, the proportion of each variable in the overall difference were calculated AND Freidman Test was used.

INCOME TAX AND Labour supply is an important part in public sector Economics. INCOME TAX affects labour supply which in turn affects the national INCOME. Economic theory cannot predict the effect of TAX on Labour supply, because are in opposite directions. This research is concerned with the effect substitution AND INCOME effects of TAXation on labour supply by an econometric study of cross-sectional data. It is assumed that the effect of TAXation is to alter budget constraints. Because different individuals have different gross wage rates AND different amounts of other INCOME, they have different budget constraints. If difference in preferences are adequately controlled for, it is possible to derive labour supply estimates from the cross-sectional data which can then be used as basis for estimating the effect of TAXation. In this study we show that the effects of net wage rate on labour supply is significant, that non wage INCOME is not significant. We finally recommend a policy for TAX refoRm by changing the marginal TAX rate.

The Role of TAXes in reduction of economic inequalities, has been a controversial subject in recent decades. Destructive effects of progressive TAXes on efficiency AND problems of TAX compliance, have been considered in TAX reform programs worldwide. Introduction of an Islamic INCOME TAX system, with all its progressive features, AND its popularity seems to be effective in correcting the distributive outcomes of existing INCOME TAX system, We have compared the distributive effects of two systems, in this article, AND appraised the Khoms, as a major INCOME TAX in Isalm, to replace the corresponding INCOME TAXes, Distributive effects of two systems, were estimated by current TAX incidence approach under four TAX shifting assumptions, Suits index of progressivity, indicates that the proposed replacement in general, improves INCOME distribution. Our estimations indicate that TAX burden of Khoms is lower than that of similar TAXes. In sum, the Khoms system, improves the index of vertical equity, leading to a lesser degree of distortion in economic efficiency.

Conservatism AND TAX avoidance are among firm's policies that can be considered as TAX incentives. Evidence suggests that conservatism is a common AND accepted tool for reducing the TAX INCOME. By accepting AND noticing this matter, some questions arise: which strategies are used by listed companies in Tehran Stock Exchange to reduce their TAX INCOME, AND under circumstances that companies can reduce their TAX INCOME by using conservative accounting would their prefer to use another strategy for TAX avoidance or not? This study examines the influence of TAX INCOME AND Conservatism on TAX avoidance. Findings of investigation of 146 firms (1177 firm-years) listed in Tehran Stock Exchange in the 2002 to 2012 by unbalanced Panel model AND OLS, suggest by 95% confidence level that relation between TAX INCOME AND the Conservatism is negative AND significant. This indicates that TAX avoidance AND conservatism is mutually exclusive instruments for TAX reduction, so that conservatism is reduced by increasing the incentives for TAX avoidance AND vice versa. In addition, the negative relationship between average TAX expression of three years AND TAX avoidance indicates that firms tend to be conservative AND decline the profit for TAX savings, rather than reduce their TAX by TAX avoidance.