In the context of a new assessment of personnel requirements in psychiatry in Germany, minute estimates are to be made for the work activities of all professional groups in psychiatry. For this purpose, a guideline-based treatment should serve as the basis for the minute estimates. In order to be able to take detailed guideline-based treatment into account, catalogues of relevant guideline-based treatment options were created for 70 psychiatric case vignettes. For each case vignette, all potentially relevant guideline-based treatment options were rated by experts from all professional groups in psychiatry and by patient and family representatives using a two-stage Delphi process (RAND/UCLA Appropriateness Method). At the end of the Delphi process, all treatment options rated as relevant were compiled into a catalogue. Treatment options whose relevance was judged to be uncertain were listed separately. All irrelevant options were removed. In the next step, the catalogue of guideline-based treatment options will be used as a basis for estimating minutes of work for all professional groups in psychiatry. In conclusion, the expert-based Delphi method is well suited to derive evidence-based, guideline-concordant treatments for case vignettes as a basis for estimating minutes of work activities. Missing and outdated guidelines were a limitation.