Relationship Customer Concentration and Tax Avoidance by the Moderating Role of Managers Ability

Companies with a major customer concentration due to high business risk (risk of losing major customers) require additional cash holdings. A tax avoidance can reduce the cash outflow and create additional cash for the company. The main objective of this research is to investigate the relationship between concentration on major customers and tax evasion in companies admitted to the Tehran Stock Exchange. To measure tax evasion (effective tax rate), the ratio of the tax expense tax to net profit before deduction of tax, for the customer concentration on the ratio of major sales (sales above 10%), and for measuring the variable power of managers from the model of Damirian et al. (2012) has been used. This research is a quasi-experimental and post-event type in the field of accounting proof research and is a kind of applied research. Linear regression model has been used to test the research hypotheses. The research community is included 130 companies selected by Cochran formula in the Tehran Stock Exchange during the period 2011 to 2016. The results of statistical tests of the first hypothesis showed that there is a negative and significant relationship between customer concentration and tax avoidance. In other words, in major customer companies, higher effective tax rates and tax avoidance have been lower. Also, the results of the study showed that the managers power as a moderating variable, weakens the relationship between customer concentration and tax avoidance.