Due to the large variety of actors, channels, and materials involved, the processes of the circular economy are very complex. This complexity makes it difficult to maintain consistent data quality throughout the supply chain. Circular processes can only be applied extensively if enough data, for example supplier information, is available. Data and information from suppliers, manufacturers, end-users, and recyclers are not shared transparently through circular processes. One reason is the insufficient support from IT systems for data exchange between the different parties. To improve data exchange, a product-independent process view of the closed-loop supply chain based on the supply chain operations reference model is introduced in this work. Then, an approach is presented to improve data quality in closed-loop supply chain processes through data-based models. The human-in-the-loop method is used to capture data and enable integration of this approach in IT systems for closed-loop supply chains. Therefore, a more transparent data flow laying the foundation for improved data quality throughout the supply chain can be achieved.