This paper describes the estimation of a new tax e ort index for 120 developing countries over 1990-2012. Two major innovations are the use of a new measure of non-resource tax revenues and the correction of the traditional method of tax e ort estimation by accounting for structural economic and human vulnerabilities. The results indicate that economic vulnerability is harmful to tax while human asset enhances tax. Moreover, Sub-Saharan African countries exhibit an outstanding vulnerability-adjusted tax e ort compared to the other countries.