Economic order quantity under conditions of a one-time-only extended permissible delay period in payments

In today's business environment, a supplier usually offers customers a permissible delay for settling outstanding account balance for the goods supplied. However, a supplier on occasion may allow this permissible delay in payments to be more than the usual during a given specified period. In this paper, we establish an appropriate model for a customer to determine its optimal special order quantity when the supplier offers a special extended permissible delay for one time only during a specified period. We then establish two theorems for a customer to find the optimal special order quantity. Finally, several numerical examples are given to illustrate the theoretical results.