However, the sustentation of these programs is overcome complex, data that the exchange reserves are finite under flow of capitals or speculative attacks. Estimating an internal disequilibrium proceeding from a rise generalized in the level of prices of one determined country, the imported goods and services are cheaper of what in the market intern. This implies an increase of the demand for verge foreign, occurring, then, an excess of demand for verge in the level of the exchange tax. When one is in purely flexible an exchange regimen, this disequilibrium is corrected by the depreciation of the currency of the country, or, in other words, with an increase in the exchange tax. In a flexible exchange regimen, the monetary authority does not have commitment some to support one definitive tax of exchange. All the fluctuations in the demand and in offer of foreign currency are made comfortable by means of the alteration of price of the foreign currency in relation to the national one. The Central banking defines offers monetary without if compromising to a specific exchange tax, allowing that it floats in reply to the economic riots. It offers of foreign currency is supplied by the foreign, exporting tourists of goods and services, receivers of external and borrowed investments of loans and financings of the Exterior.
Of the side of the demand, the agents are the Brazilian tourists, Brazilian investors in the Exterior, the importers of goods and services, the companies who repatriate investments external or pay to profits and shares on them and those who amortize or pay to interests on loans caught in the Exterior.O regimen of tax of purely flexible exchange have, according to Simonsen and Cysne (1995), three great attractive ones. She assures the automatic balance of the rocking of payments, becoming irrelevant the volume of international reserves. She isolates, with this, the monetary politics of the transactions with the Exterior, not having supervits nor dficits external that they pressure the monetary base. .