Although in theory, they differ their rules of granting, conditions and general target of clients, it is a matter of both loans and payday loans, credits and credits have a common point. These are, of course, interest, i.e. the additional costs associated with the commitment. The vast majority are an integral part of the money that is borrowed, there is interest. Their existence is completely natural – institutions must eventually earn something. However, there are ways to deduct interest – how does it work?