Tax Administration 2025 is the 13th edition of the OECD Centre for Tax Policy and Administration’s comparative information series. First published in 2004, the primary purpose of the Tax Administration Series (TAS) is to share information that will facilitate analysis and dialogue on the design and administration of tax systems.
This edition of the TAS provides internationally comparative data on aspects of tax systems and their administration in 58 advanced and emerging economies. While the publication traditionally put its emphasis on performance-related data and ratios for the latest available fiscal year, in this case 2023, a key focus of this edition is a 10-year perspective on the evolution of tax administration.
The publication presents the results of the International Survey on Revenue Administration (ISORA). To provide the longer-term perspective, it compares the latest ISORA data with the 2014 data collected through the very first ISORA survey.
The ISORA survey is a multi-organisation survey to collect information and data on tax administration. It is governed by five partner organisations: the Asian Development Bank (ADB), the Inter-American Center of Tax Administrations (CIAT), the International Monetary Fund (IMF), the Intra-European Organisation of Tax Administrations (IOTA) and the OECD.
To provide further insight into the ISORA data in certain places, TAS 2025 also uses data from the Inventory of Tax Technology Initiatives (ITTI). ITTI is an online database containing information on technology tools and digitalisation solutions implemented by tax administrations across the globe. It has been developed by the OECD’s Forum on Tax Administration (FTA) together with nine key partner organisations.
This report was approved by the Committee on Fiscal Affairs on 29 October 2025 and prepared for publication by the OECD Secretariat.