§ 13. "That Section nineteen of the Finance (No. 2) Act, 1939 (which fixes the relation of excess profits tax to the national defence contribution) shall not apply to the national defence contribution for any accounting period or part of an accounting period falling after such date as may be fixed by any Act of the present Session relating to Finance for the termination of excess profits tax, and that amendments consequential on the termination of excess profits tax shall be made in the enactments relating to the assessment and collection of the national defence contribution."