PROBLEM TO BE SOLVED : To raise collection efficiency of service charge for real estate management of a condominium, etc. SOLUTION : A fixed amount according to a paid amount to a demand for the service charge addressed from a management part of housing complex to each house is returned to payers of each house by points. In addition, when payment of service charge is overdue, all or a part of the accumulated points to be returned are eliminated. Thus, the payers of each house come to positively perform payment within a payment period, sales of the condominium is advantageously advanced and property purchasers are corraled besides enhancement of sales ratio of merchandise sale by use of the points in E-commerce linked with the payment. COPYRIGHT : (C)2007, JPO&INPIT