G. Galeotti* and M. Marrelli** *Universita di Perugia **Universita di Napoli 1. The economic analysis of optimal taxation has permitted considerable steps to be taken towards the understanding of a number of problems: the appropriate degree of progression, the balance between different taxes, the equity-efficiency trade-off etc .. Though at times considered as abstract and of little use in policy design, the issues it addresses are real ones and very much on the agenda of many countries. As usual in scientific debate, criticisms have contributed to the correct understanding of the theoretical problems involved and made clear that, at the present state of the art, definitive conclusions may be premature. A first well-taken criticism addresses the assumption, underlying optimal taxation models, of a competitive economy with perfect information on the part of individual agents and full market clearing. Once we leave the Arrow-Debreu world, it is no longer necessarily the case that taxes and transfers introduce distortions on otherwise efficient allocations.