The probability of IT project failures can be mitigated more successfully when discovered early. To support an early detection, transparency regarding a project’s cash flows shall be increased. Therefore, an appropriate analysis and calculation of a project’s costs, benefits, risks and interdependencies is inevitable. Until today, however, a method that appropriately considers these factors when estimating the ex ante project business case does not yet exist. Using the Action Design Research approach, we designed, applied and tested a practicable and integrated method of determining the monetary value of IT projects to generate generalized insights to benefits management. This method was conjointly developed by practice and academia, to ensure practical applicability while upholding scientific rigor. Furthermore, to support understandability of the method, we provide an application example.