In various industries, there has always been the possibility of planning the behavior of companies based on the companies in the same industry in which they operate, and in the term, the effect of industry preemption. Since the estimation of peers' effects has been a major challenge for empirical studies, it is necessary to measure this issue in the case of tax avoidance. Based on this, in this research, the effects of competition have been investigated specifically on the tax avoidance of companies and considering the role of market competition. The current research is applied in terms of purpose and using the post-event approach, and based on the method, it is descriptive-correlation type. The number of 120 companies admitted to the Tehran Stock Exchange during the years 2016 to 2021 have been investigated as accessible society. To test the hypotheses, multivariate regression was used in the Eviews10 software. The findings of the research show that the effect of industry preemption on corporate tax avoidance is maintained, and in monopolistic industries with less competition, the effect of industry preemption on tax avoidance also decreases. Based on this finding, it can be said that in Iran, the industry's leading effect on tax avoidance is more based on the theory of competition, and in situations where the need to gain a competitive advantage is less felt, this effect is less visible.