Voluntary contributions – often earmarked for specific purposes – have become an indispensable source of revenue for international organizations (IOs) and the UN organizations in particular. While the reasons for this trend are regularly studied, its effects on the internal functioning of the organization (especially on the ‘international public administration’ (IPA) as the organization's secretariat) remain unclear. Given this gap, we study the consequences of increasing financial dependence for the autonomy of IPA staff. Using financial and personnel data of 15 UN agencies over time, our results are in line with the intuitive expectation that more financial resources in the form of voluntary contributions increase the number of staff. We also find evidence, however, that the more an organization depends on voluntary resources (within its broader financial portfolio), the more it reduces the ratio of permanent staff among its total workforce in the subsequent years. The underlying adaption of IPAs’ recruitment and career structures to growing financial insecurities has important implications for the autonomy of international bureaucrats and needs to be considered also in terms of its long-term impact on administrative professionalism and organizational performance.