The importance of seigniorage relative to other sources of government revenue differs markedly across countries. This paper tries to explain this regularity by studying a political model of tax reform. The model implies that countries with a more unstable and polarized political system will have more inefficient tax structures and, thus, will rely more heavily on seigniorage. This prediction of the model is tested on cross-sectional data for 79 countries. We find that, after controlling for other variables, political instability is positively associated with seigniorage. (JEL E52, E62, F41)