The main objective of the present work is to analyze and assess the impact of corruption on tax revenues, using static and dynamic panel data approaches. As a first step, we analyze the impact of corruption on total tax revenues for 63 emerging and developing countries over the period 1996-2016. Our results suggest that the impact is significantly negative on total tax revenues as a percentage of GDP. Second, we study the effects of corruption on direct taxes/GDP and indirect taxes/GDP. The estimates reveal that direct taxes are more affected by corruption than indirect taxes. This suggests that tax reforms aimed at increasing tax revenues could usefully focus on changes to indirect taxes, while efforts to combat corruption in tax collection should concentrate on direct taxes.