This paper presents a new corporate microsimulation model, ZEW TaxCoMM, which allows for the coherent micro-based analysis (ex ante and ex post) of reform induced revenue implications and the distribution of the tax burden between firms of different characteristics. In this paper, ZEW TaxCoMM is employed to evaluate the consequences of the 2008 German corporate tax reform. The German corporate tax reform of 2008 has brought about important cuts in corporate tax rates, which were at the same time accompanied by significant changes in the determination of the tax base for both major German corporate taxes - corporate income tax and trade tax. The reform followed the distinct and internationally prevalent pattern of tax rate cut cum base broadening. Hence, the results on the distribution of the tax burden according to firm characteristics stand exemplarily for those reforms which follow a similar pattern. Especially in view of the current economic crisis, questions on the distribution of the tax burden among firms of different characteristics have arisen and still remain at the heart of the academic and political debate in Germany and other countries. As a result, the ZEW TaxCoMM simulations show that less than 5% of all corporations did not benefit from the 2008 German corporate tax reform. The average annual relief as measured by the average decline in the effective tax burden on cash flows amounts to 2.8 percentage points for large corporations and to 6 percentage points for small corporations. Clearly, small firms benefited more. As to tax revenues, the reform induced decrease amounts to € 9.8 billion. The decline in tax revenues is more important for the corporate income tax. The trade tax thus gains fiscally in importance. Furthermore, the simulation illustrates that firms with low profitability, high debt ratio and high capital intensity benefit least from the reform. This is a consequence of the reform detaching the tax base from profits by banning the deduction of business expenses. This additionally endangers the existence of firms in times of massive economic downturn. Indeed, policy makers in Germany and other countries reacted by modifying the most harmful regulations which implied the taxation of economic worth instead of profits.