On the other hand, force the BC to keep an adequate volume of reserves to take care of to the excesses of demand for verge that, porventura, can occur. Moreover, the maintenance of fixed taxes of exchange depends on two other requirements: that the taxes of inflation of the different countries are sufficiently next and that the economic agents believe the support of the exchange tax. If it has an expectation of exchange depreciation, the Central banking can try to delay rationing it the supply of exchange for the importers of goods and services and the exporters of incomes. However, it cannot prevent that the exporters of goods and services postpone its foreign activities and nor that economizers interrupt the entrance of capitals in the Pas.Segundo Zini Jnior (1996), the commitment to keep the fixed tax of exchange, in the conditions where misalignments in the domestic politics motivate speculative flows of capitals, has been routinely treated for the low investors as promise to credibility, a time that no country obtained to keep the fixed tax of exchange in last the 20 years. Two factors corrode the credibility of the regimen of fixed tax of exchange. First, to adjust the economy, she is necessary to promote contraction. Data that the shocks economic they tend if to distribute asymmetrically for the different countries, the mechanism of adjustment of this system demands difficult and custosas contractions on the job level.
The other factor inhabits in who controls the expansion of the liquidity in the group of countries that adheres to the fixed exchange, a time that different countries have distinct preferences how much to the priority attributed to the combat of the inflation or the defense of the job level. In this direction, the system of fixed tax of exchange tends to introduce politics conflicts enters the participants of the system. Leiderman and Bufman (1995) mention that the fixed taxes of exchange are excellent anchors for the desinflao programs.