USAID has been using the Collecting Taxes Database (CTD) since it was launched in 2008 to promote tax system assessment and measurement as a means to promote improvements in tax policy and tax administration. With the rise of other databases and increased work on tax analysis in recent years, USAID reviewed and updated the CTD methodology and indicators in 2017-2018. More than 40 indicators were initially examined and collected during a pilot phase. To ensure consistency with evolving good practice and to account for the recent publication of other databases, CTD was modified and now comprises a set of 20 indicators.