Exemption of airline income from foreign taxation ensures reciprocal relief and mandates refunds for previously paid taxes. The Agreement exempts, on the principle of reciprocity, income of an enterprise of one Contracting State derived from the operation of aircraft in international traffic from tax in the other Contracting State, including participations in pools, joint ventures and interest on funds directly connected with such operations; it enters into force after exchange of letters certifying internal procedures, applies to income from international air operations after 1 July 1966, and obliges each State to refund taxes or deposits paid by the other State's designated airline on exempt income if claimed within six months of entry into force.