In today's globalized environment, tax motives have begun to play an increasingly prominent role in a company's (re)location decision. Because of this development, national states have to ensure that their tax systems remain competitive in order to attract new investments (and the corresponding taxable income). However, in doing so, they should refrain from introducing tax measures which qualify as harmful tax competition, since these may have potential negative effects on the tax base of other states. The Organisation for Economic Co-operation and Development's (OECD's) 1998 Report on 'Harmful Tax Competition: An Emerging Global Issue' and the European Commission's Code of Conduct on business taxation both aim to curb harmful tax practices by establishing the criteria which can be used to identify harmful preferential tax regimes. In addition, the state aid provisions can be used to fight harmful tax competition. The purpose of this article is to evaluate six Belgian tax incentives in search of any potentially harmful features. As will be demonstrated below, it appears there are still a number of loopholes in the current state of legislation, which mainly relate to the special tax regime for expatriates and the excess profit ruling system.