
Johannes Gaul, M.Sc.
E-Mail: johannes.gaul uni-mannheim.de
Phone: +49 (0) 621 – 1235 169
Adress: Universität Mannheim
Schloss Ostflügel
68131 Mannheim
Teaching
Bachelor:
- Bachelor Thesis
- Basics of Financial Accounting
Master:
- Seminar- und Masterarbeiten
Mannheim Master Accounting and Taxation:
- Seminar- und Masterarbeiten
Research Interests
- Real Effects of Taxation
- Political Economy
Publications
- Gaul, J., Gundert, H., Nikolay, K., Spengel, C., Spix, J., Steinbrenner, D., Weck, S. and Wickel, S. (2024). Deutschland im internationalen Steuerwettbewerb: Auswirkungen aktueller Reformansätze. Der Betrieb : DB, 77, 1158-1163.
- Spengel, C., Klein, D., Müller, J., Pfrang, A., Schulz, I., Winter, S., Gaul, J., Weck, S. and Wickel, S. (2023). Die globale Mindeststeuer – Kosten und Nutzen aus deutscher Sicht. Der Betrieb : DB, 76, 1–14.
- Gaul, J., Keusch, F., Rostam-Afschar, D. and Simon, T. (2025). Invitation messages for business surveys: A multi-armed bandit experiment. ZEW Discussion Papers, 25–003. Mannheim.
- Gaul, J., Keusch, F., Rostam-Afschar, D. and Simon, T. (2024). Invitation messages for business surveys: A multi-armed bandit experiment. TRR 266 Accounting for Transparency Working Paper Series, 170. Mannheim.
- Gaul, J., Klein, D., Müller, J., Pfrang, A., Schulz, I., Spengel, C., Weck, S., Wickel, S. and Winter, S. (2022). Die Kosten der globalen Mindeststeuer in Deutschland. ZEW policy brief, 2022–07. Mannheim.
- Gaul, J. and Asatryan, Z. (2024). Tax competition networks. 2024 Public Finance Conference, ZEW Mannheim, Mannheim, Germany.
- Gaul, J. (2023). Networks of tax competition. 116th Annual Conference, National Tax Association, Denver, CO.
- Gaul, J. (2023). Tax competition networks. 5th Swiss Workshop on Local Public Finance and Regional Economics, Lugano, Switzerland.
- Gaul, J. (2023). Tax competition networks. Taxation and Mobility Workshop, Mannheim, Germany.
- Gaul, J., Keusch, F., Rostam-Afschar, D. and Simon, T. (2023). Invitation messages for business surveys: A multi-armed bandit experiment. TRR 266 Annual Conference, Mannheim, Germany.
- Gaul, J., Rostam-Afschar, D. and Simon, T. (2023). How to cold call firms? An application of multi-armed bandit optimization in corporate web surveys. 10th Conference of the European Survey Research Association (ESRA), Milano, Italy.
- Gaul, J. and Simon, T. (2023). How to cold call firms? An application of multi-armed bandit optimization in corporate web surveys. 45. Annual Congress European Accounting Association (EAA), Helsinki, Finland.
Projects
BAK Taxation Index 2024/
2025 In the context of a growing international economic integration, taxation becomes a more and more central factor in the competition of regions and countries for international investment and skilled employees. From that perspective, in addition to the effective level of company taxation also the effective tax burden on highly skilled employees is important: Due to the growing international mobility of highly skilled employees, these employees compare net incomes and force companies to bear international and interregional differences in compensation tax burdens. The present research project will analyze effective tax burdens on corporations and on highly skilled employees in Switzerland for 2024. Additionally, it will analyze the effective tax burden in more than 50 different locations from 19 European countries, the U.S. and Asia for 2025. Thereby, it will update and analytically extend the BAK Taxation Index, which has been published first in 2001. In addition, the implications of the global minimum tax in Switzerland will be analyzed.
The Provision of Effective Tax Rates and Related Supporting Services – Backward-looking Effective Tax Rates
In its Communication on Business Taxation in the 21st Century, the European Commission emphasises the need for a sound, efficient and fair tax framework that meets public financing needs while supporting recovery, sustainable growth and investment. In this context, corporate tax systems and their complexity play an important role in the investment decisions of domestic and foreign companies.
Given the rapid pace of change in taxation, it is important to have the tools and data to analyse the evolution of corporate tax systems and their impact on business decisions. Comparable time series data on the evolution of effective tax burdens are essential as they can inform the policy debate on the impact of corporate taxation. In addition, the data allow the analysis of potential distortions from taxation.
The decision effects of taxation always refer to the future tax burden associated with a particular business decision. Forward-looking tax rates reflect the decision-related tax burden and are therefore best suited for analysing the decision and incentive effects of corporate taxation. In contrast, backward-looking tax rates are always based on empirically observed data, i.e. they do not capture the incentive effects of tax provisions, but reflect the tax consequences of actual business decisions (including tax optimisation and the use of tax incentives). Backward-looking effective tax rates can be derived from company data (unconsolidated or consolidated accounts) or from macroeconomic data.
The project includes a comprehensive review of the literature on backward-looking effective tax rates, the joint development of a common methodology for calculating backward-looking indicators of the effective level of corporate taxation with the EU Commission and the OECD, and the creation of a database of backward-looking effective tax rates, complemented by detailed annual reports.
BAK Taxation Index 2022/
2023 In the context of a growing international economic integration, taxation becomes a more and more central factor in the competition of regions and countries for international investment and skilled employees. From that perspective, in addition to the effective level of company taxation also the effective tax burden on highly skilled employees is important: Due to the growing international mobility of highly skilled employees, these employees compare net incomes and force companies to bear international and interregional differences in compensation tax burdens. The present research project will analyze effective tax burdens on corporations and on highly skilled employees in Switzerland for 2022. Additionally, it will analyze the effective tax burden in more than 50 different locations from 19 European countries, the U.S. and Asia for 2023. Thereby, it will update and analytically extend the BAK Taxation Index, which has been published first in 2001. In addition, the implications of the global minimum taxation in Switzerland (STAF) will be analyzed.
Talks
- 2023: Tax reforms – triggers and effects, Budget and Finance Days 2023, German University of Administrative Sciences, Speyer, Germany
- 2024: Development potentials of the data infrastructure for analyzing tax measures using the example of DAC7, Annual Conference – Network for Empirical Tax Research, Berlin, Germany
- 2024: Panel NeSt – Network Empirical Tax Research of the BMF, Annual Conference Association for Social Policy (VfS), Berlin, Germany