Taxation optimale et réformes fiscales dans les PED. Une revue de littérature tropicalisée

Since the beginning of the 80’s, the developing countries have been forced to launch a fiscal reform. Most African countries are currently right in the middle of this reform process. This reform has two objectives: first, to increase fiscal pressure; second, to substitute domestic taxes to custom and excise duties. The reform of domestic taxes very quickly focussed on the implementation of VAT. When domestic taxes are increased, the distortive impact on market equilibria (=efficiency effect) as well as the redistributive impact (=equity effect) of the increase has to be taken into account. In order to do so, a theoretical framework is needed to help design fiscal policies based on optimality criteria: that is implementing taxes having a small distortive impact on market equilibria, while reducing social inequalities. The optimal tax theory provides us with a reference framework: it allows the definition of « optimal » tax rates, which lead to the maximisation of collective welfare for a given level of fiscal receipts. This paper tries to evaluate reforms applied in developing countries using criteria based on the optimal tax theory. It seems that it is mainly the efficiency criterion, rather than the equity one, which prevaled when these reforms were implemented.