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Global MNC Tax Complexity Project

The Global MNC Tax Complexity Project is a joint research project of Deborah Schanz (LMU Munich) and Caren Sureth-Sloane (Paderborn University), both Germany. It is part of the DFG-funded Transregional Collaborative Research Center TRR 266 Accounting for Transparency. The aim of the Global MNC Tax Complexity Project is to identify the determinants of tax complexity, to develop and maintain an index measuring the level of tax complexity across countries [Tax Complexity Index, TCI] and to examine the effects of tax complexity.

Tax Complexity Index

The Tax Complexity Index measures the complexity of a country’s corporate income tax system as faced by multinational corporations. The index covers the complexity of the tax code (complexity inherent in different tax regulations) and the complexity of the tax framework (complexity that arises from the features and processes of a tax system). It can range between zero (not complex) and one (extremely complex). The underlying data is obtained through a global survey of local tax consultants of major tax services firms and networks (PARTICIPANTS).
This cross-country data comprises a rich set of drivers and dimensions of the tax code and tax framework complexity. The survey is conducted every two years. At the moment, the website shows the results of the surveys 2016, 2018, 2020 and 2022.

Starting in 2022, we applied a minor adjustment to our methodology for calculating tax code complexity. Now, regulations deemed “not applicable” by over 50% of respondents in a country are assigned a tax code complexity value of 0. Data from survey waves of 2016, 2018, and 2020 remain unchanged. However, as an intertemporal consistency check, we simulated the revised approach for 2016, 2018, and 2020 and found only minor deviations. Simulated data are available upon request.

Suggested Citation

We thank Caren Sureth-Sloane, Deborah Schanz and their team for sharing data from their Global MNC Tax Complexity Project with us, www.taxcomplexity.org. For further information on the survey and index construction see Hoppe, Schanz, Sturm, Sureth-Sloane (2023): The Tax Complexity Index – A Survey-Based Country Measure on Tax Code and Framework Complexity, European Accounting Review, 32 (2): 239-273. DOI: 10.1080/09638180.2021.1951316.

Project Related Publications

Executive Summaries:

Identification of Tax Complexity Drivers:

Hoppe, Thomas, Schanz, Deborah, Sturm, Susann & Sureth-Sloane, Caren (2018). What are the Drivers of Tax Complexity for MNCs? Global Evidence. Intertax, 46 (8/9): 654-675. Available at SSRN.

Development of the Tax Complexity Index:

Hoppe, Schanz, Sturm, Sureth-Sloane (2023): The Tax Complexity Index – A Survey-Based Country Measure on Tax Code and Framework Complexity, European Accounting Review, 32 (2): 239-273. DOI: 10.1080/09638180.2021.1951316.

Tax Complexity and Foreign Direct Investments:

Euler, I., Harst, S., Schanz, D., Sureth-Sloane, C. & Voget, J. (2024). Tax Complexity and Foreign Direct Investment. TRR 266 Accounting for Transparency Working Paper Series No. 160. Available at SSRN.

Hoppe, T., Schanz, D., Sturm, S., Sureth-Sloane, C. & Voget, J. (2020). The Relation between Tax Complexity and Foreign Direct Investments: Evidence Across Countries. TRR 266 Accounting for Transparency Working Paper Series No. 13. Available at SSRN.

Studies on Individual Countries:

Siegel, F. & Schanz, D. (2024). Was treibt Steuerkomplexität in Deutschland? — Eine Analyse für die Jahre 2016 bis 2022. Steuer und Wirtschaft – StuW, 101 (2): 143-157.

Sturm, S. (2021). Income tax complexity faced by multinational corporations: A comparative study of Canada, the United States, and other selected OECD Countries. Canadian Tax Journal, 69 (3), 745-790. DOI: 10.32721/ctj.2021.69.3.sturm.

Hoppe, T. (2020). Tax Complexity in Australia – A Survey-Based Comparison to the OECD Average. Australian Tax Forum, 35 (4): 451-475.

Hoppe, T., Safaei, R., Singleton, A. & Sureth-Sloane, C. (2019). Tax Complexity for Multinational Corporations in South Africa – Evidence from a Global Survey, in: Evans, C., Franzsen, R. & Stack, Elizabeth (Ed.), Tax Simplification – An African Perspective. Pretoria University Law Press, Pretoria: 267-293.

Hoppe, T., Rechbauer, M. & Sturm, S. (2019). Steuerkomplexität im Vergleich zwischen Deutschland und Österreich – Eine Analyse des Status quo, Steuer und Wirtschaft, 96 (4): 397-412. Preview available here [in German].

Hoppe, T., Schanz, D., Sturm, S. & Sureth-Sloane, C. (2017). Warum ist unser Steuersystem so komplex? Eine befragungsbasierte Analyse, Die Wirtschaftsprüfung, 70 (17): 1026-1033 [in German].