Distortional effects of separate accounting and formula apportionment on factor allocation
R. Ortmann, E. Pummerer, Journal of Business Economics (2023).

Income Shifting and Management Incentives
R. Ortmann, D. Schindler, Income Shifting and Management Incentives, 2022.

COVID-19 Reporting and Willingness to Pay for Leisure Activities
R. Ortmann, S. Warkulat, S. Krull, N. Klocke, M. Pelster, COVID-19 Reporting and Willingness to Pay for Leisure Activities, 2021.

Real effects of an international tax reform for MNEs
R. Ortmann, D. Simons, D. Voeller, Real Effects of an International Tax Reform for MNEs, 2021.

COVID-19 and investor behavior
R. Ortmann, M. Pelster, S.T. Wengerek, Finance Research Letters 37 (2020).

Uncertainty in Weighting Formulary Apportionment Factors. How Does Weighting Uncertainty Impact After-Tax Income of Multinational Groups?,
R. Ortmann, Uncertainty in Weighting Formulary Apportionment Factors. How Does Weighting Uncertainty Impact After-Tax Income of Multinational Groups?, 2015.

Formula Apportionment or Separate Accounting? Tax-Induced Distortions of Multinationals' Locational Investment Decisions
R. Ortmann, E. Pummerer, Formula Apportionment or Separate Accounting? Tax-Induced Distortions of Multinationals’ Locational Investment Decisions, 2015.

Uncertainty in Weighting Formulary Apportionment Factors
R. Ortmann, Die Betriebswirtschaft 75 (2015) 161–177.

Can the CCCTB Alleviate Tax Discrimination against Loss-Making European Multinational Groups?
R. Ortmann, C. Sureth-Sloane, Can the CCCTB Alleviate Tax Discrimination against Loss-Making European Multinational Groups?, 2014.