The Tax Cuts and Jobs Act of 2017 (TCJA) introduced substantial changes to the U.S. corporate tax system, including a lower statutory tax rate and the adoption of a more territorial-like international tax framework. Many of the international provisions were meet with significant uncertainty regarding implementation and application for corporate tax positions. We present a theoretical framework that models a firm’s choice regarding the amount of risk firms are willing to take on their tax positions. We empirically test our predictions using measures of tax risk, uncertainty, and firm-level behavior before and after the TCJA. Our results suggest that the positive association between tax uncertainty and tax avoidance declines significantly after the TCJA, particularly for firms with tax haven subsidiaries. Our findings suggest that policy interventions that reduce incentives for elaborate tax planning can meaningfully reduce corporate tax risk-taking. This evidence provides insights for policymakers and stakeholders seeking to lower incentives for highly risky and aggressive tax planning strategies.