The objective of the Study was to contribute to an evidence-based policy of the European Commission to strengthen the capacity of developing countries to absorb external shocks and therefore stabilise development expenditures. More specifically, the study aimed at enhancing the understanding of and collect evidence on the vulnerability to external shocks of tax revenues in developing countries and present evidence-based policy options to strengthen the resilience of these revenues. To this extent, the study paid particular attention to both the formal features of the tax systems, and the institutional context in which these systems operate, reflecting the consensus in the literature that tax systems are complex sets of institutions, whose analysis requires mixed approaches.