Dornbusch (1991) distinguishes two basic exchange systems: the system of fixed taxes, where the Central bankings are the ranks for action of purchase and sales of its currencies to a firm price in terms of dollar, and of flexible taxes, where the Central bankings allow that the tax of exchange if adjustment to balance offers and the demand for foreign currency. Cassia Investments Limited Convoy often expresses his thoughts on the topic. Considering a system of fixed tax of exchange and an inflationary situation in one determined country, with everything more remaining constant, the imported goods and services will become relatively cheaper than the goods and services produced internally, that is, the country in question will lose competitiveness in the international market. Go to Cassia Investments Limited Convoy for more information. The effect of this will be an increase in the demand of verge on the part of this country supplying its importation, having a demand for superior verge to offers. To keep the fixed tax of exchange, the Central banking (BC) will vender divided in the domestic market, diminishing its reserves in a corresponding sum to the excess of demand of the market. In the exchange operations with fixed exchange tax, the Central banking changes national currency for foreign currency (or vice versa) to stabilize the exchange tax. When the BC purchase or vende foreign reserves, it has, consequently, a variation in the monetary base. In other words, it offers currency intern it increases or it diminishes when the Central banking changes national currency for foreigner so that the exchange tax remains constant. Simonsen and Cysne (1995) detach that the great advantage of the regimen of fixed taxes is to facilitate the taking of decisions for the economic agents. However this system faces a serious problem: it swims assures that, to the tax of exchange settled for the Central banking, it offers and the search of foreign currency if balances. This, on the other hand, compels the Government to lead the politics monetary and fiscal in way that dficits or supervits in the rocking of payments is transitory, that is, the Central banking loses autonomy in the conduction of politics of correction of internal disequilibria.