We quantify behavioral responses to estate taxation by exploiting two large and opposing reforms in Taiwan. A fundamental challenge is that estates are observed only at death, complicating treatment assignment. To address this, we link administrative estate and wealth records to implement a prediction-based difference-in-difference design. We estimate elasticities of taxable estates of 2.8 for the tax increase and 0.5 for the tax cut. Several patterns indicate wealth-shifting avoidance rather than real wealth changes: liquid assets reported at death diverge from pre-death holdings, closely held firm owners inflate liabilities to reduce book values, and heirs’ labor supply remains stable despite sizable inheritance shocks. We interpret the asymmetry through a simple model of avoidance with sunk costs, suggesting that the tax-increase elasticity better reflects the long-run response. This would imply a revenue-maximizing rate of 21% that is close to the OECD-average top statutory rate today.