The split share structure reform removes a significant market friction in China's capital market by allowing previously non‐tradable shares to be freely tradable at market prices. Such a reform reduces the agency conflict between controlling shareholders and minority shareholders as the former now care more about stock prices. We find that state‐owned firms, but not non‐state‐owned firms, significantly increased their tax avoidance activities after the reform. We attribute this differential effect to the dual role of the government as state‐owned firms’ controlling shareholder as well as the tax claimant. Further, this effect is more pronounced for state‐owned firms that are more likely to be influenced by the government prior to the reform. Finally, the reform reinforces a positive association between tax avoidance and firm value. Overall, our study suggests that when controlling shareholders are more concerned about stock prices, state‐owned firms engage more in tax avoidance activities to enhance firm value.