The research group analyses the relevance of individual and institutional determinants of social assistance receipt, the duration and the dynamics of benefit receipt. To evaluate the impact of the German tax-benefit system on individual labour supply decisions and the take-up of social assistance benefits, the research group employs a static microsimulation model (IAB-MSM). The analysis of restrictions and resources of welfare recipients and their households on labour market participation and welfare dependency is based on survey data as well as on register data. The research group is responsible for the register based research data “Sample of Integrated Welfare Biographies” (SIG).