Commodity Tax Structure under Uncertainty in a Perfectly Competitive Market

In a partial equilibrium setting without price uncertainty, the balanced-budget substitution of an ad valorem tax on output for a specific (unit) tax can enhance welfare in imperfectly competitive markets and is without impact in a competitive world. This paper demonstrates that a substitution of this kind can also increase expected output and welfare in a competitive market characterised by uncertainty about the commodity price, if firms can respond to the revelation of demand conditions by altering output.