Large pending fiscal policy changes, such as in the United States in 2012 or in Japan with consumption taxes, often generate considerable uncertainty. “Fiscal cliff” episodes have several features: an announced possible future change, a skewed set of possible outcomes, the possibility that implementation may not actually occur, and a known resolution date. This paper develops a model capturing these features and studies their impact. Fiscal cliff uncertainty shocks have immediate impact, with a magnitude that depends on the probability of implementation, which generates economic volatility. The possibility of fiscal cliffs lowers economic activity even in periods of relative certainty.