Business profits taxation limited to residence unless attributable to a permanent establishment, where profit attribution governs taxation. Profits of an enterprise resident in one Contracting State are taxable only there unless the enterprise carries on business in the other State through a permanent establishment, in which case only profits directly or indirectly attributable to that permanent establishment may be taxed by the other State. Attribution must reflect what the permanent establishment would earn as a distinct and separate enterprise, with reasonable estimation where exact determination is impracticable, and permitted deductions include expenses incurred for the business of the permanent establishment under the taxation law of the State where it is situated.