The permanent establishment (PE) concept is a threshold issue which must be confronted and addressed by virtually every enterprise seeking to conduct trading activities in one or more countries other than its home country. Whether or not an enterprise has a -permanent establishment -- in a country defines whether its trading income can be taxed or is exempt under a network of over 1,000 bilateral income tax treaties and some local laws. Today, the interaction of rapidly changing rules, increased enforcement, and evolving business operations creates a challenging environment for tax directors of global businesses who must understand and manage their company --s PE risks.