Today, companies need to quickly adapt to business changes and react to customers' tendencies and market demands in an unpredictable environment. In this field, the analytical systems represent an important asset that each company should have and use. Data Warehousing Systems (DWS) support companies' analytical needs, however, the development and integration of the data systems is a critical part. Due to specificities of the involved data, each DWS is unique, which compromises the use of reusable components or even the use of pre-built solutions. In this paper, we propose a standard skeleton for a DWS based on Portuguese Audit Tax documents (SAF-T (PT)). These documents represent a standardized procedure for every Portuguese company, providing the necessary data about billing, accounting, and taxation. Thus, they can provide the foundations to use them as a standard data representation to create a DWS that can be posteriorly explored by analytical techniques to generate useful insights.