This dissertation deals with the taxation of corporate actions and the difficulties of the transition between the taxation of capital income before and after the introduction of the German flat rate withholding tax on capital gains ("Abgeltungsteuer") as of 1.1.2009. The complicated special rules of section 20 subsection 4a Income Tax Act are analysed in detail and compared with the former taxation rules for capital income. For existing deficiencies and shortcomings solutions are developed. After the comprehensive enquiry of section 20 subsection 4a Income Tax Act the author examines whether the special rules for corporate actions are consistent with the principles of the constitutionally required protection of legitimate expectations. The Federal Constitutional Court's requirements for the retroactivity of tax laws form the standard of review for this analysis.