6(1)For the purposes of this Schedule the amount payable on redemption, on exercise of the option under a provision for redemption (the provision concerned), constitutes a deep gain if it constitutes such a gain by virtue of sub-paragraph (2) or (4) below (or both).
(2)The amount payable on redemption (on exercise of the option under the provision concerned) constitutes a deep gain if the issue price of the security is less than the amount so payable, and the amount by which it is less represents more than—
(a)15 per cent. of the amount so payable, or
(b)half Y per cent. of the amount so payable, where Y is the number of complete years between the day of issue and the day on which the occasion for redemption under the provision concerned falls.
(3)Sub-paragraph (4) below applies where the security became subject to—
(a)a qualifying provision for redemption (the prior provision), or
(b)qualifying provisions for redemption (the prior provisions),
before it became subject to the provision concerned.
(4)The amount payable on redemption (on exercise of the option under the provision concerned) constitutes a deep gain if the base amount is less than the amount so payable, and the amount by which it is less represents more than—
(a)15 per cent. of the amount so payable, or
(b)half Y per cent. of the amount so payable, where Y is the number of complete years between the base day and the day on which the occasion for redemption under the provision concerned falls.
(5)For the purposes of sub-paragraph (4) above—
(a)the base amount is the amount payable on redemption on exercise of the option provided for by the prior provision (if there is only one) or the last of the prior provisions (if there are two or more), and
(b)the base day is the day on which the occasion for redemption falls under the prior provision (if there is only one) or the last of the prior provisions (if there are two or more).
(6)For the purposes of sub-paragraph (5) above the last of the prior provisions is the one to which the security last became subject.