The corporate tax reform of 2008 leads to profound changes in tax law that will have effects far beyond the year 2008. The reform impacts the taxation and financing of corporations and partnerships, as well as trade tax and the foreign tax law, and indirectly results in changes to depreciation and life insurance. Important aspects include the introduction of an interest barrier and a reinvestment allowance for partnerships. Additionally, the flat tax on capital gains is introduced, effectively abolishing the half-income procedure for dividends from stocks. The work explains all the practically relevant changes of the reform and provides valuable recommendations for tax-optimized consulting under the new law. The authors also describe the motives of the legislator, providing consultants with all the information needed to interpret the new regulations.