Tax Administration 2025

Reader’s guide

Tax Administrations covered by the report

Tax Administration 2025 is the 13^th edition of the TAS. The primary purpose of the series, which commenced in 2004, is to share information that will facilitate dialogue among tax officials on important tax administration issues, and to identify opportunities to improve the design and administration of their systems.

This edition of the series provides internationally comparative data on various aspects of tax systems and their administration in 58 advanced and emerging economies. It covers 54 jurisdictions that are members of the OECD’s FTA. In addition, it includes information on the non-FTA jurisdictions that are members of the European Union as well as Morocco and Thailand (which increases the report’s geographical coverage).

ISORA data gathering process and reporting

The 2025 Tax Administration publication presents the results of the ISORA, the last version of which was launched in September 2024. ISORA is a multi-organisation international survey that collects national-level information and data on tax administration. It is governed by five partner organisations: the ADB, CIAT, the IMF, IOTA and the OECD. The 2024 ISORA survey was completed by 164 jurisdictions.

The ISORA survey

The ISORA survey consists of two parts:

1. An annual survey part, collecting data mainly on the annual operational performance of tax administrations; and

2. A periodic survey part, looking at the wider tax administration processes and arrangements which are less likely to change regularly, such as governance, human resource management and compliance risk management.

The ISORA survey that was launched in September 2024 covered the annual survey part. The comprehensive version of the survey, covering both the annual and the periodic survey parts, was last conducted in 2023 and is expected to be run again in 2028.

The different ISORA survey forms can be accessed via the ISORA online data portal (https://isoradata.org; accessed on 1 October 2025) in the section “Documents”.

Survey management

The last five iterations of the ISORA survey collected data for fiscal years from 2018 to 2023. Survey information was gathered online using the IMF’s RA-FIT data collection tool. Participation was voluntary and 164 administrations completed the 2024 ISORA survey. Each partner organisation supported participants by assisting them with the completion of the ISORA survey, based on an upfront agreed allocation key. The 58 administrations included in this publication corresponds to the group of administrations supported by the OECD.

While all data contained in the publication has been subject to a high-level review by the OECD, neither the OECD nor any other partner organisation formally validated the data. As a result, all data included in the publication should be considered as self-reported by the administrations concerned.

Publication of data

Since July 2025, the ISORA data is made available to the public on the ISORA online data portal (https://isoradata.org). The data from the 2024 ISORA survey was published in July 2025.

Historically, the OECD made all ISORA data for TAS participants also publicly available through the TAS and its data annex. This approach changed with the 2024 edition of the TAS. Since then, the TAS does not anymore have its own data annex. Instead, it refers to the publicly available tables on the online data portal. (It should be noted that with the launch of the new ISORA data portal in July 2025 and the decommission of the old data portal, the links to the ISORA data included in the TAS 2024 publication do not work anymore. Readers should instead refer to the data tables on the new portal. See Annex A.)

As regards the other organisations:

• The ADB publishes jurisdiction-level ISORA data for its members, for example, A Comparative Analysis of Tax Administration in Asia and the Pacific: Eighth Edition (Asian Development Bank, 2025[1]).

  CIAT publishes in aggregated form as well as selected data points, for example, Innovation, Digitalization and Technology Index (INDITEC): A tool for benchmarking Tax Administrations at the international level (Based on data from ISORA 2020 Survey) (Morán and Díaz de Sarralde Miguez, 2024[2]), and Overview of Tax Administrations in CIAT Countries: Results of ISORA 2023 - Volume II (Special forms) (Garcimartín and Díaz de Sarralde Miguez, 2025[3]).

• The IMF publishes in aggregated form as well as on selected data points, for example, ISORA 2018: Understanding Revenue Administration (Crandall, Gavin and Masters, 2021[4]) and Revenue Authorities and Their Boards of Management: Recent Developments (Crandall et al., 2024[5]).

Data comparability

TAS 2025 includes performance-related data, ratios and other information for the fiscal years from 2018 to 2023. The data was collected through different rounds of the ISORA survey. Several administrations updated some of their previously supplied data during the process of producing the 2025 edition of the TAS. For that reason, there might be some differences between this and previous editions of the TAS in figures and tables displaying 2018 to 2022 data.

In several areas, TAS 2025 also uses fiscal year 2014 data from the 2016 ISORA survey to show trends for the 10-year period between 2014 and 2023. However, over the past years a number of changes were made to ISORA questions to improve clarity and data quality. Therefore, care needs to be taken when comparing results from the different ISORA versions, and the wording of survey questions compared whenever relevant. The different ISORA survey forms can be accessed on the ISORA online data portal (https://isoradata.org) in the section “Documents”.

Also, it should be noted that statistical data is often subject to revisions after publication. As a result, some data may not correspond to what has been published by administrations. For example, it may be that opening balances of a specific year (t) may not correspond to closing balances of the preceding year (t-1) that were published in earlier editions of this publication.

Even more care should be taken when comparing ISORA data with data gathered through pre-ISORA surveys, i.e. data included in the sixth and prior editions of the TAS. When the ISORA survey was initially created and at the request of survey participants, the partner organisations made considerable effort to agree and document a range of words and terms used in the survey and their meaning. While this has improved data integrity and comparability between administrations, comparisons with pre-ISORA data may be limited as definitions may now exist for terms not previously defined, or in some instances, have changed.

Further, in relation to combined tax and customs administrations, it should be noted that the data in this publication refers to the tax administration activities of such administrations. The data may therefore not be directly comparable with key performance indicators published by them as these indicators may include both tax and customs related data.

Data from the Inventory of Tax Technology Initiatives

To complement the ISORA survey data, this edition of the TAS continues to draw on data from the ITTI database which contains information on technology tools and digitalisation solutions implemented by tax administrations globally. ITTI has been put together with the assistance of the ISORA partners, the African Tax Administration Forum, the Cercle de Reflexion et d’Echange des Dirigeants des Administrations Fiscale, the Commonwealth Association of Tax Administrators, the Pacific Islands Tax Administrators Association and the Study Group on Asia-Pacific Tax Administration and Research. (OECD et al., 2025[6])

The inventory data was collected in 2024 and 2025 through a global survey on digitalisation and can offer further insight into the ISORA data in certain places. Therefore, where available, the TAS uses the ITTI data published in the 2025 OECD report Tax Administration Digitalisation and Digital Transformation Initiatives (OECD, 2025[7]).

Publication structure

The tax administration series examines the fundamental elements of modern tax administration systems and uses data analysis and examples supplied by tax administrations to highlight key trends, recent innovations, and performance measures and indicators.

Structure

The main body of the publication is structured around nine chapters: (i) an introduction followed by chapters on (ii) responsibilities and revenue collections; (iii) registration and identification; (iv) assessment; (v) services; (vi) compliance management; (vii) collection; (viii) disputes; and (ix) budget and workforce.

The publication also contains two annexes:

• Annex A holds an overview of the ISORA data tables published on the ISORA data portal (https://isoradata.org).

  Until the 11^th edition of the TAS, this annex replicated the ISORA data for the 58 tax administrations1 covered in the publication. Starting with the 12^th edition, i.e. TAS 2024, Annex A contains an overview of, and the links to, the data tables that hold the latest available annual and periodic ISORA data.

• Annex B has the details of the administrations that participated in this publication.

Tables and figures

The source notes below the tables and figures in the main body of the publication refer readers to the underlying tables on the ISORA data portal. In some cases, they may refer to previous editions of the TAS or, where ITTI data is used, to the relevant sections in the 2025 ITTI report (OECD, 2025[7]).

The figures in the publication are also accompanied by hyperlinks (OECD StatLinks) that direct readers to corresponding MS Excel spreadsheets containing the underlying data. These links are stable and will remain unchanged over time.

Symbols and abbreviations that are used in the ISORA data tables are explained at the bottom of each table. The reader should note that where no data is shown for a specific jurisdiction in a table this is primarily due to the question not being applicable to a particular jurisdiction, or an opening question to a sub-section of the survey being answered in the negative and, therefore, the jurisdiction did not have to answer the follow-up questions.

Forum on Tax Administration

The FTA is a unique body bringing together tax commissioners and tax administration officials from over 50 OECD and non-OECD economies. The FTA is a forum through which tax administrators share knowledge, undertake research and develop new ideas to enhance tax administration around the world. Readers wishing to find out more about the FTA should go to: https://www.oecd.org/en/networks/oecd-forum-on-tax-administration.html. For more information on the OECD’s work on tax administration, please visit: https://www.oecd.org/en/topics/tax-administration.html. (Both links accessed on 1 October 2025.)

Caveat

Tax administrations operate in varied environments, and the way in which they each administer their taxation system differs in respect to their policy and legislative environment and their administrative practice and culture. As such, a standard approach to tax administration may be neither practical nor desirable in a particular instance. Therefore, this report and the observations it makes need to be interpreted with this in mind. Care should be taken when considering a jurisdiction’s practices to fully appreciate the complex factors that have shaped a particular approach. Similarly, regard needs to be had to the distinct challenges and priorities each administration is managing.

References

[1] Asian Development Bank (2025), A Comparative Analysis of Tax Administration in Asia and the Pacific: Eighth Edition, Asian Development Bank, Manila, https://doi.org/10.22617/TCS240621-2.

[5] Crandall, W. et al. (2024), Revenue Authorities and Their Boards of Management: Recent Developments, IMF Technical Notes and Manuals 2024/05, International Monetary Fund, Washington, DC, https://doi.org/10.5089/9798400282881.005.

[4] Crandall, W., E. Gavin and A. Masters (2021), ISORA 2018: Understanding Revenue Administration, International Monetary Fund, Washington, DC, https://doi.org/10.5089/9781513592930.087.

[3] Garcimartín, C. and S. Díaz de Sarralde Miguez (2025), Overview of Tax Administrations in CIAT Countries. Results of ISORA 2023. Volume II (Special forms), Inter-American Center of Tax Administrations, Panama, https://www.ciat.org/Biblioteca/Estudios/2025_overview_II.pdf (accessed on 1 October 2025).

[2] Morán, D. and S. Díaz de Sarralde Miguez (2024), Innovation, Digitalization and Technology Index - INDITEC 2023: The digital transformation of Tax Administrations in the period affected by the COVID-19 pandemic (Based on data from ISORA 2022 Survey), Inter-American Center of Tax Administrations, Panama, https://www.ciat.org/Biblioteca/DocumentosdeTrabajo/2024/WP-01-24-inditec.pdf (accessed on 1 October 2025).

[7] OECD (2025), Tax Administration Digitalisation and Digital Transformation Initiatives, OECD Publishing, Paris, https://doi.org/10.1787/c076d776-en.

[6] OECD et al. (2025), Inventory of Tax Technology Initiatives, https://www.oecd.org/content/oecd/en/data/datasets/inventory-of-tax-technology-initiatives.html (accessed on 1 October 2025).

Note

← 1.  For Japan, given that it publishes its currency figures in millions the currency figures included in tables have been added a suffix of “000” in order to fit the survey requirements that currency figures needed to be provided in thousands. For Switzerland, in the context of the ISORA survey the term “tax administration” refers to the Swiss Federal Tax Administration. All duties performed by the Swiss cantonal or communal tax administrations are not attributed to the Federal Tax Administration and are therefore not included. This concerns in particular PIT and CIT, where the Federal Tax Administration merely performs a supervisory function. If a service is indicated as not performed by the “tax administration”, this respective service may be rendered by the Swiss cantonal and/or communal tax administrations.