Tax aggressiveness is an action taken by companies to manipulate taxable profits so as to reduce the tax burden that must be paid by companies to the state through legal means (tax avoidance) by taking advantage of loopholes in laws and tax regulations as well as illegal methods (tax evasion) such as intentionally not report part or all of the profits so that the tax burden is low. This study is to determine the effect of firm size, profitability, and leverage on tax aggressiveness. The object of this research is a mining company listed on the Indonesia Stock Exchange for the period 2018-2020. This research was conducted with a quantitative descriptive approach. The method used is descriptive statistical analysis, classical assumption test, multiple linear regression analysis, and hypothesis testing. This study uses secondary data obtained from the Indonesia Stock Exchange (IDX) and the websites of each company. The results of this study are firm size has no significant effect on tax aggressiveness, while profitability and leverage have a significant effect on tax aggressiveness.