Annex C. Methodology

The results and analysis used in this report draws upon three different exercises.

The results obtained for the publication were based on a perception survey carried out by the OECD in English, French, Spanish and Arabic during the last quarter of 2019 and first quarter of 2020. The survey was disseminated among tax officials participating in OECD's Global Relations events and trainings, as well as by requesting OECD country representatives to distribute it among officials from their Administrations. Although the survey was anonymous, respondents were asked to identify their country, function / unit, years of experience, and field.

The survey aimed to capture the perceptions that tax officials have on the tax behaviour of large/multinational companies, and on the Big Four consulting firms. The ‘Big Four’ are the four largest consulting and auditing companies (Deloitte, KPMG, EY and PricewaterhouseCoopers).

The survey was based on responsible tax principles and voluntary codes of conduct adopted by businesses, more specifically, on the Business at OECD Statement of Tax Best Practices for Engaging with Tax Authorities in Developing Countries (Business at OECD, 2013[1]) and on the Codes of Conduct for Responsible Tax Practice, where available, from the Big Four (not all the Big Four have such codes of conduct). These principles and codes of conduct outline the standards of behaviour expected in a range of areas including compliance, communication, and transparency.

The survey was then divided into two sections, the first one concerning perceptions of MNEs/large business behaviour and the second one referring to the behaviour of Big Four firms. For the MNEs/large business, the survey addressed the following issues:

  • Transparency and trust

  • Dispute resolution

  • Political lobbying

  • Staff retention

  • Responsiveness to requests

  • Timeliness of payments

  • Bribery

  • Views on voluntary principles

  • Commitment to cooperation

  • Tax incentives

  • Public commitment to taxation

  • Behaviour compared to local business

Regarding the Big Four firms, the survey mainly focused on the following issues.

  • Transparency and trust

  • Role in recruitment

  • Staff retention

  • Aggressiveness/spirit of the law

  • Influence on client behaviour

  • Behaviour vis-à-vis local advisors

For further details, please see the complete survey in the following link:

The survey was answered by 1 240 officials (most of them tax auditors) working in Tax Administrations in 138 countries. The results have been grouped by regional averages; Africa (34 countries, 206 responses), Asia (31 countries, 372 responses), LAC (30 countries, 325 responses) and OECD regions (25 countries, 225 responses). The regional groups are in line with the approach taken in previous work in the OECD tax morale and tax certainty literature (see (OECD, 2019[2])). The data have been smoothed to ensure that no country is over-represented in the sample, with a maximum weighting of one country of 10% per region.

Several sensitivity exercises were undertaken to ensure the robustness of the results. For instance, age and rank were controlled for as to see if the results varied with age or position. Once these variable were controlled for, the results continued to hold.

Previous results from the tax certainty work (see (IMF/OECD, 2017[3]), (IMF/OECD, 2018[4]) and (OECD, 2019[2]), and its corresponding survey and results were also used to complement the perceptions of tax administrators. The aim of the tax certainty survey was to explore the nature of tax uncertainty, its main sources and effects on business decisions, and obtain a set of concrete and practical approaches to help policymakers and tax administrations shape a more certain tax environment.

The survey was circulated using the OECD network of government officials, tax practitioners, civil society and businesses, including the OECD’s Business Industry Advisory Committee (BIAC). The survey was open between October and December 2016 and received 724 responses from firms headquartered in 62 different countries. Country-specific responses were also aggregated by region (Africa, Asia, LAC and OECD). This approach provides significantly different numbers of observations in each region, and also has significantly different numbers of observations per country, though in no region was the most frequent country chosen by respondents responsible for more than 35% of responses.

To complement the empirical results provided by both surveys, a set of virtual regional roundtables were organized between December 2020 and May 2021:

  • LAC Roundtable on Tax Morale (18-20 May 2021)

  • African Roundtable on Tax Morale (27-28 April 2021)

  • OECD/IOTA Roundtable on Tax Morale (20 January 2021)

  • Asia Roundtable on Tax Morale (7-8 December 2020)

The meetings were co-hosted by the OECD and key regional partners including the IOTA, CIAT, ATAF, the Study Group on Asian Tax Administration and Research (SGATAR) and the Asian Development Bank (ADB)

The roundtables gathered Administrations, MNEs operating in the region, tax professionals and relevant business associations. Its goal was to facilitate a dialogue between businesses and governments to discuss in more depth the findings of the surveys, focusing on identifying key issues for both MNEs and Tax Authorities, and potential tools and approaches to use going forward, all participants received a background document with a summary of results, and an initial analysis of the key findings relevant to the region, this was complemented by a presentation provided by the OECD secretariat on the survey results. The rest of the roundtables consisted of a combination of moderated panel discussions and breakout room discussions. Over 150 participants from Africa, 160 from IOTA member countries, 160 from LAC, and 130 participants from Asia attended these roundtables. With delegates from nearly 100 countries in total participating.


[1] Business at OECD (2013), BIAC Statement of Tax Best Practices for Engaging with Tax Authorities in Developing Countries,

[4] IMF/OECD (2018), Update on Tax Certainty: IMF/OECD Report for the G20 Finance Ministers and Central Bank Governors,

[3] IMF/OECD (2017), Tax Certainty: IMF/OECD Report for the G20 Finance Ministers,

[2] OECD (2019), Tax Morale: What Drives People and Businesses to Pay Tax?, OECD Publishing, Paris,

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