This chapter introduces Congestion Income (CI) and the process of Congestion Income Distribution (CID), including the history and evolution of the process and how Congestion Income is regulated. An overview of the Congestion Income Distribution methodology for day-ahead allocation is provided, followed by the principles of the methodology. Negative Congestion Income linked to non-intuitive flows is discussed, as well as efforts by Transmission System Operators to deal with such occurrences. The important role of slack hubs is introduced, as well as the situations leading to remuneration inconsistencies and the impact of reserving some of the day-ahead capacity for balancing purposes. Finally, challenges associated with cross-Capacity Calculation Region Congestion Income transfers are presented.