Public administrations are experiencing a process of change and modernisation towards the search for greater efficiency and effectiveness schemes. In this process, new approaches to management – such as the ones that consider the crucial role of intangibles – might well contribute to the effort. Consequently, the present paper explores the role of intellectual capital in public administrations, in an attempt to measure and manage intangibles based on knowledge in such organisations. In particular, we propose a model, building on the literature and the empirical study of two public units at the National Tax Authority in Spain: the Fiscal Studies Institute (IEF) and the Tributary Agency (AEAT).