The article presents the special features of an evaluation within mental health services research in Germany. The experiences of the evaluation of flexible and integrated treatment options with a global treatment budget in psychiatric hospitals based on routine data of more than 70 statutory health insurance (SHI) funds (EVA64 study) are systematically presented. Using the EVA64 study as an example, recommendations for the use of claims data in the field of mental health services research and in general are derived. (1) First, the study and the use of claims data in this study is described and classified. (2) Then, the individual outcomes of the study are presented and evaluated to (3) derive criteria, strengths and potential uses of claims data. (4) Finally, recommendations for the further development of claims data from SHI funds as a basis for evaluation are described.