§ 10. "That—
- (a) Excess Profits Duty under Part III. of the Finance (No. 2) Act, 1915, as amended or extended by any subsequent enactment, shall, unless Parliament otherwise determine, be charged for any accounting period ending on or after the first day of August, nineteen hundred and nineteen, and before the fifth day of August, nineteen hundred and twenty; and
- (b) Excess Profits Duty shall be an amount equal to forty per centum instead of eighty per centum of the excess profits for any accounting period commencing on or after the first day of January, nineteen hundred and nineteen, or in the case of an accounting period which has commenced before that date, but ends after that date, forty per centum instead of eighty per centum of so much of the excess profits as may be apportioned to the part commencing on that date."