The Organisation for Economic Co-operation and Development (OECD) has released the report Tax Administration 2024, which provides comparative insights into the tax systems and administrations of 58 OECD member countries and other advanced and emerging economies.

Tax Administration 2024 is the twelfth 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.

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.

This edition of the TAS provides internationally comparative data on aspects of tax systems and their administration in 58 advanced and emerging economies. It 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.

The publication presents the results of the last four rounds of the International Survey on Revenue Administration (ISORA) launched between September 2020 and September 2023. The last survey iteration combined the annual and periodic parts of the ISORA survey, with the periodic part only being included every five years.

The ISORA survey is a multi-organisation survey to collect information and data on tax administration. It is governed by four partner organisations: the Inter-American Center of Tax Administrations (CIAT), the International Monetary Fund (IMF), the Intra-European Organisation of Tax Administrations (IOTA) and the OECD. The Asian Development Bank (ADB) also participated in those ISORA surveys along with the four partner organisations.

To provide further insight into the ISORA data in certain places, TAS 2024 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 together with nine key partner organisations.

This report was approved by the Committee on Fiscal Affairs on 25 October 2024 and prepared for publication by the OECD Secretariat.