This report is the twelfth edition of the OECD's Tax Administration Series. Containing a wealth of data and other information from 58 jurisdictions, it is intended to be used by tax administration analysts allowing them to understand the design and administration of tax systems in other jurisdictions and to draw cross-border comparisons. While primarily aimed at analysts, it can also be a useful tool for senior tax administration managers or officials in ministries of finance when considering changes in tax system administration. The 2024 edition includes performance-related data, ratios and trends up to the end of the 2022 fiscal year. For the first time since 2019, this edition also examines in more detail the administrative, operational and organisational practices of participating tax administrations. Finally, it contains a special feature which explores how tax administrations are estimating tax gaps. The underlying data for this report comes from the International Survey on Revenue Administration, and in certain areas it also uses information from the Inventory of Tax Technology Initiatives.