Innovative eCustoms solutions play an important role in the pan-European eGovernment strategy. The underlying premise is interoperability postulating a common understanding of processes, services and the documents that are exchanged between business and government organizations as well as between governmental authorities of different EU member states. This article provides a stringent approach for deriving documents and services from current eCustoms procedures based on the UN/CEFACT standards framework and for embedding these in a service oriented architecture for Collaborative eGovernment. In doing so, we put a special focus on document engineering by applying the UN/CEFACT Core Component Technical Specification (CCTS), a conceptual framework for modeling document components in a syntax neutral and technology independent manner. By relying on CCTS, we want to tackle the challenge of handling different document configurations imposed by divergent national legislations, different cust...