The expansion of ‘social duties’ has been a prominent feature in the development of social policy and the welfare state. Drawing on unique time-series data in the database of SCIP (Social Citizenship Indicators Project), this article describes and analyses the development of ‘social duties’, primarily in the form of taxes and social insurance contributions, in eighteen countries from 1930 to 1990. In focus are the institutional and longitudinal variation in the increase and change in these duties and how they have been distributed among employers, the insured and state authorities.