A tax revenue mobilization in less developing countries is an empirical debate and has received a lot of attention. Reflecting this, increasing tax to GDP ratio is a policy option that needs special attention in developing countries, especially the lower income economies. Meanwhile, this study intends to examine the determinants of Tax revenue to GDP ratio among four East African Community Countries (EAC-4). Analysis is conducted using Fixed and Panel data approach using most recent data from 2010-2020.The sample countries are four (4) East African Community (EAC) members. The results suggest that, economic growth has significantly positive contribution to tax revenues while growth of the agricultural sector retards tax revenue collections. The impact of manufacturing sector and service sector on tax revenue is insignificant. To improve tax revenue performance, an improvement and implementation of the designed tax policy is needed in these countries to properly tap growth of all economic sectors.