One important aspect of the 2008 reform of business taxation is the interest barrier. It puts a limit on the amount of interest expenses deductible from earnings, thus reducing the tax bill. Therefore, it aims to prevent tax substrate from fleeing to other countries. This article starts with a description of the legal situation before and after the tax reform 2008 and the resulting tax incentives for the cross-border debt financing of German subsidiaries, through which prof-its made in Germany are transferred to lower-taxing countries abroad. Further, we look at the aforementioned interest barrier, and its accompanying effects in terms of incentives and bur-dens. Using data supplied by the Federal Statistical Office, the number of companies affected by the interest barrier and the expected tax revenue resulting from various scenarios are esti-mated.