The OECD has produced the TAS, its comparative information series on tax administration, since 2004. Since that time the publication has grown in terms of its coverage, influence and importance and is now widely recognised as an authoritative source of information on tax administration around the globe.
The 2025 Tax Administration publication presents the results of the ISORA survey, the last version of which was launched in September 2024. It would not have been possible without the direct support and help of a large number of people, particularly the staff in the 58 tax administrations that provided data and jurisdiction examples, reviewed content and responded to feedback and questions on the data and text that form the basis of the publication.
The authors of the publication were Paul Marsh, Fiona May and Oliver Petzold all from the OECD Centre for Tax Policy and Administration (CTPA) Secretariat. Management and analysis of the ISORA data was undertaken by Oliver Petzold. They would also like to thank the administrative team at the OECD CTPA Secretariat for their work on the publication, and the OECD CTPA’s Communications team.