Accounting for Tax Complexity

Schanz, Sureth-Sloane, and Voget investigate the determinants and consequences of tax complexity by establishing and maintaining a novel survey-based measure, the Tax Complexity Index. This measure allows the A05 team to capture both tax code complexity—the complexity of regulations—and tax framework complexity—the complexity of tax procedures, such as tax audits from legislative and administrative tax processes. A05 uses this measure to study the determinants of tax complexity, such as digitalization of tax processes and new anti-tax avoidance regulation. The project also assesses the consequences of tax complexity for firms’ decisions such as real investments and the organization of tax departments. It contributes to the understanding of the implications of impaired transparency.

  • Forschungsfrage

    How can tax complexity due to a lack of tax transparency be measured, what are its drivers, and how does it affect economic decisions of corporations and the interplay between taxpayers and tax authorities?

  • Motivation zur Forschung

    Firms contribute to society not only through their goods and services but also by paying taxes. Transparency issues around taxation involve the transparency of the tax system as perceived by tax subjects, such as firms, tax authorities, and the general public. In a highly dynamic global tax landscape, tax complexity and thus the lack of regulatory and administrative transparency is often seen as a substantial challenge.

  • Forschungsprogramm

    In the second funding period, we will further study tax complexity based on our dataset in conjunction with additional resources to understand tax complexity and its potential implications on firms, regulators, and societies across countries and time. We will continue to collect data on tax consultants' perception of tax complexity in further waves of the Global MNC Tax Complexity Survey. These data enable us to deduce novel insights on the developments of tax complexity across countries and over time and the effect of firms’ digitalization and new tax regulations on tax complexity. We will use the tax complexity data to further investigate firms' foreign direct investment in the presence of tax complexity, extending the static perspective of Hoppe et al. (2020). Moreover, we will study the effect of highly complex tax systems on tax department structure by investigating to what extent tax complexity affects the location of tax employees. Additionally, we will study the effect of tax complexity on compliance. Further, we will investigate how tax complexity affects the outcomes of MAPs across countries and continue examining how the complexity of transfer pricing regulations leads to double taxation under the strategic interactions of tax authorities and firms.

  • Research Contribution

    We contribute theoretically and empirically to the understanding of the drivers and consequences of regulatory complexity at large and help identify undesired forms of tax complexity. A05 provides the basis for discussions on where to enhance regulatory transparency. Overall, we add to international policy debates on appropriate taxation and simplification of the tax environment and thus the overarching goal of the CRC. The tax transparency data can inform policymakers and regulators to strive for tax simplification and can inform studies on real effects as conducted in B01, B02, B04, and B08.


We developed the Tax Complexity Index: it measures the complexity of a country’s corporate income tax system as faced by multinational corporations. You can find the index and more information about the project at  


We recently conducted two surveys and presented:

Verwandter Inhalt


Beteiligte Institutionen

Die Hauptstandorte vom TRR 266 sind die Universität Paderborn (Sprecherhochschule), die HU Berlin und die Universität Mannheim. Alle drei Standorte sind seit vielen Jahren Zentren für Rechnungswesen- und Steuerforschung. Hinzu kommen Wissenschaftler der LMU München, der Frankfurt School of Finance and Management, der Goethe-Universität Frankfurt, der Universität zu Köln und der Leibniz Universität Hannover, die die gleiche Forschungsagenda verfolgen.