Consumer satisfaction is an essential factor in the ongoing business process. Companies must be able to meet consumer
demands and to consider customers’ concerns on price. In a supplier and customer relationship, a given discount will
affect the order size. Besides, in the current developing industry, the business must consider environmental factors
without disturbing. Recently, researchers and practitioners develop environmentally-friendly sectors so that the
environment will be well managed and not polluted. For example, they can control carbon emissions by optimizing
production operations and product distribution. This paper presents a study on the relationship between discount on
the economic order quantity model and the total carbon emissions. This research develops a procurement model by
considering an all-unit discount system and carbon emission tax. The aim is to determine the optimal order that
minimizes the total cost.