The purpose of this study is to investigate the moderating effect of board characteristics on the relationship between effective tax rates and company value. The information obtained in relation to the research variables was entered into an Excel spreadsheet and then analyzed using Ives software. The statistical population of this research is the systematic elimination method from among 149 companies listed on the Tehran Stock Exchange during the period 1390 to 1399. The results showed that board size does not have a significant effect on the relationship between effective tax rate and company value, but board independence, duality of CEO duties, gender diversity of the board and board financial specialization have a significant positive effect on the relationship between effective tax rate and company value. Also, the effective tax rate has a positive and significant effect on the value of the company. Regarding the analysis of the results from the researcher's point of view, it can be said that the size of the board of directors is an important link between the company and its external resources that managers need to maximize the performance and value of their well-established companies. The mere presence of independent directors on the board does not guarantee good corporate governance. Some independent managers may be appointed to meet only the minimum regulatory requirements. When a CEO manages several boards at the same time, it has a negative impact on the value of the company, but the duality of the CEO can also have a positive effect on the value of the company. The appointment of women to each board should be motivated by their presence increasing the financial value of the company and should not be seen merely as a symbolic move for gender equality as a result of pressure from external institutions. Increasing the financial expertise of the board can reduce information asymmetry.