This module deepens climate budgeting by examining how to assess the financial costs and benefits of climate actions compared with business-as-usual scenarios. Participants explore different impact assessment methods used by cities of Tampere, Aarhus and Norderstedt, including cost-efficiency and cost–benefit analyses, and learn how these calculations are impacted by different scenarios. The module also demonstrates how results can be visualized and explained in an accessible way – ensuring that complex financial insights effectively support informed decision-making, with the Climate Action Decision Support (CADS) Tool developed in the Climate-4-CAST project.