System and Method for applying discount selectively and automatically

PURPOSE: A system and a method for paying with a credit card using a selectively and automatically discounted rate are provided to expand the sales by providing direct benefits to consumers. CONSTITUTION: In case that a credit card holder starts to perform a payment, articles purchased or services provided are inputted to a POS(Point Of Sale) terminal or a credit card transaction authorization device(S10). A control module of a payment agent installed in a member store client calculates an amount to be paid(S20). Credit card related information is read through a reader connected to the member store client(S30). A card sort checking module judges whether a sort of a credit card is set by a setting module(S40). A discounted object checking module checks whether articles and services to be discounted are included in article purchased(S50). The control module applies a discount rate to the articles or the services checked. In addition, the control module calculates an amount of money paid(S60). Information on the amount of money is transmitted to a server(S70).