The box b is a has separate of it has main or official, where is saves money not declared for certain expenses. Initially, box b was used as petty cash to cover some minor daily expenses, however, is currently also improperly used to handle large volumes of money without declaring it to the Treasury.
It is that saves money black, opaque to taxation, which does not pay taxes, which does not officially exist and disappoint everyone else, full money. These boxes there are many in the world. According to the papers of Panama, more than 200,000 businesses use them in this country. Here in Spain, those who most use them tend to be a party.