In recent years, the long-standing principle that the courts of one country will not enforce the penal and revenue laws of another country has been significantly eroded. A range of international agreements and cross-border developments have increased tax authorities’ powers to exchange information and give mutual assistance to collect tax debts. This has resulted in a widening of the tax net beyond domestic borders. However, these powers must be exercised within the confines of domestic legislation and the provisions of relevant international treaties. In each case, it must be determined whether enforcement action is within the confines of the law.