Enterprise Resource Planning (ERP) systems continue to gain importance in today’s tough global environment. Organizations are making large investments in ERP systems because of their promised benefits. Several observations have been made in the literature which suggest that organizations should avoid tailoring the ERP systems as much as possible while implementing and using them. It is assumed that this approach will result in realizing the likely benefits of ERP systems. However, because of ever evolving requirements and individual needs of the organizations, even a ‘Vanilla’ package has to undergo through customization. Literature on the ERP systems provides different typologies of the ERP customizations. However, there is a pressing need for a new and refined typology as the functionality of the ERP packages has matured and advanced over the years. This paper is intended to present the re-conceptualization of the ERP customization typology and, moreover, it aims to develop new assessment criterion that can be used to assess the impact of the different types of customizations.