The difference between the bank's rate and the Central Bank's: the cost nobody shows
The PTAX is the reference rate published by the Central Bank, calculated from market quotes throughout the day. It is not the rate your company closes at: it is the thermometer. The rate you close at comes with a spread: the difference between the market reference and the price the institution offers you. That spread is the compensation of whoever executes the deal, and it is perfectly legitimate. The problem is when it is never discussed. Comparing the closed rate with the reference from the same time of day turns a conversation of "seemed good to me" into a number. It is the difference between negotiating and accepting. Calculate the spread on your last transaction against the day's PTAX (in Portuguese) →
All-in rate (VET): the only one that matters
VET stands for Valor Efetivo Total, the total effective value. It is the cost of the whole operation (exchange rate, fees and taxes) expressed as a single rate per unit of currency. It exists precisely to prevent the classic scene: an attractive rate up front and an IOF (financial transactions tax), a remittance fee and a local handling cost behind it. The VET is the standardized way of expressing that total cost. Ask for the VET in writing before closing: it is information that rarely comes up on its own in the conversation. Two quotes are only comparable by their VET. And remember: the taxation of foreign exchange varies with the nature of the transaction and changes over time. It is always worth checking what is in force on the date, not what applied last year.
Exchange advances (ACC and ACE): what they actually are
ACC is Adiantamento sobre Contrato de Câmbio, an advance on an exchange contract. The exporter closes the exchange contract before shipment and receives the reais in advance: you bring forward today money that would only arrive later, based on an order that has yet to ship. ACE is Adiantamento sobre Cambiais Entregues, an advance on delivered exchange documents: the same logic, only after shipment, when the documents have already been delivered to the bank and you are waiting for the importer to pay. Both are credit, with a cost tied to the foreign currency, and tend to work as export funding, not as ordinary working capital in reais. When you close the contract, you also set the rate: the order stops floating. That is why ACC and ACE are, at the same time, a cash tool and a risk tool.
Locking in a rate is not a guess about the dollar
Here is the most common misunderstanding on the subject. Whoever locks in the rate is not betting that the currency will rise or fall: they are taking the currency out of the equation. The directional bet is the opposite: it is staying exposed without having decided to. The starting point is always the mismatch: how much comes in and goes out in foreign currency, and on which dates. Part of it sometimes resolves itself (revenue in dollars against costs in dollars is a natural hedge, and requires no instrument at all). What is left can be handled with instruments such as the non-deliverable forward, the NDF, which settles only the difference between the locked rate and the reference on the date, or with futures contracts on the exchange, which are standardized and marked to market daily, meaning they hit your cash before maturity. Each has a different cash and accounting consequence. Which one makes sense depends on your operation, the term and the size, not on an opinion about the exchange rate.