After the bankruptcy of Lehman Brothers, market participants have realized that a single default event can have a massive impact on credit ratings all over the world. Thus, it is essential for every bank and supervising authority to have a proper credit risk aggregation methodology. Extended CreditRisk+ provides a flexible basis to model credit portfolios with a focus on dependence structures in reference to economic risk factors. Model parameters are easy to interpret and there exists a fast, numerically stable algorithm to calculate loss distributions exactly. Our aim is to further develop this model with a special focus on cluster risk and stress testing. We want to make the model applicable to available real-world data. To summarize, our goal is to set a new modelling standard in risk aggregation and management, covering periods of financial crises. This can be an indispensable tool for governments and central banks to calculate capital requirements and to decide on bail-outs.