This paper deals with an optimal inventory model for a deteriorating item with time - dependent quadratic demand. When products are seasonal or when supplier provide price discounts for bulk orders, the retailer purchase more items and store it in their warehouses. There are two different types of warehouses. In one, the retailer owns the warehouse, and the other is rented. In this model the retailer first dispose the items in the rented warehouse and then the items present in the own warehouse because of economic reasons. Here permissible delay in payments is allowed. The model is solved analytically to minimize the total inventory cost. The result is illustrated with numerical example for the model.
 

Key words: Inventory, Deteriorating items, Quadratic demand, Delay payments, Credit period, Warehouses