A well-functioning revenue system is a necessary condition for strong, sustained and inclusive economic development. However, the revenue systems in some developing countries have fundamental shortcomings. Using Public Expenditure and Financial Accountability assessment data, this article provides a summary of the revenue raising capabilities across 58 developing countries. Tax reforms or tax system changes need to be made mindful of that current capacity. The optimal choice of tax regime may be different when administrative capacity is low. The increasing globalisation of economic activity adds a further layer of complexity that developing countries need to manage in building and maintaining their revenue systems. Finally, any proposals to change the revenue system in a developing country need to recognise that, like developed countries, tax reforms are highly political endeavours.