Certificate of Residence requirement: non-resident taxpayers must obtain a prescribed government certificate before claiming treaty relief. Section 90A is amended so that Chapter X-A applies to an assessee even if not beneficial to him, and a non-resident assessee may claim relief under an agreement only upon obtaining a prescribed certificate of residence from the government of the specified territory; a further Explanation deems meanings assigned by notification to undefined agreement terms to have effect from the date the agreement came into force.