چکیده (انگلیسی):

The purpose of this research is to study the relationship and impact of the effective factors on Tax
aggressiveness and Tax diagnostic difference decrease. The study is based on the analysis of samples include 113
companies listed in Tehran Stock Exchange for the time period from 2009- 2013. The samples are selected through
the Systematic Elimination Method. The applied statistical methods include the multivariate regression test and F
statistics as well as step by step method. In this research, income smoothing, independent auditor reporting tax
paragraph, prior period adjustments have been studied, among factors which could be effective on tax
assertiveness and tax diagnostic difference. The results indicate that prior year’s adjustments just have been
effective on the tax assertiveness and tax diagnostic difference. In fact there is a significant relationship between
the prior year’s adjustments and tax assertiveness and tax diagnostic dereference in the companies.