Cash payment linking method using accumulation of double sales margin, and linking system thereof

Disclosed are: a double-incentive margin management method for increasing mutual sales between an owned business and a competitive business or between heterogeneous businesses through cross promotion and sales support between heterogeneous businesses or between homogeneous businesses; and a system for performing the same. A double-incentive margin management system comprises a web server, an incentive margin accumulation server and a purchase service provision server. The incentive margin accumulation server accumulates an incentive margin between incentive-designated stores. The purchase service provision server (i) recognizes an identification code of the corresponding incentive-designated store among a plurality of designated stores designated in advance as incentive-designated stores if a normal purchase is requested, (ii) accumulates an incentive margin of the pre-designated designated store according to the success of product sales, (iii) stores an incentive margin of a purchaser and a margin for a desi