AbstractWe study the impact of fiscal revenue shocks on local fiscal policy. We focus on the very volatile revenues from the immovable property gains tax in the canton of Zurich, Switzerland, and analyze fiscal behavior following large and rare positive and negative transitory revenue shocks. We apply causal machine learning strategies and implement the post-double-selection LASSO method to identify the effect of revenue shocks on public finances. We find that local policymakers predominantly smooth transitory fiscal shocks.