Term used in double taxation agreement (although it may also be used in national tax legislation) to refer to a situation where a non-resident entrepreneur is taxable in a country; that is, an enterprise in one country will not be liable to the income tax of the other country unless it has a “permanent establishment” thorough which it conducts business in that other country. Even if it has a PE, the income to be taxed will only be to the extent that it is ‘attributable’ to the PE.