454Chargeable increases
(1)This section applies for the purposes of section 453 (charge on increase in value of shares of dependent subsidiary).
(2)In a case within section 453(1)(a) (dependent subsidiary at time of the acquisition) there is a “chargeable increase” in the value of the shares if the value of the shares at the appropriate time exceeds their value at the time of the acquisition.
(3)In subsection (2) “the appropriate time” means whichever is the earlier of—
(a)the end of the period of 7 years after the date of the acquisition, and
(b)the time when the employee ceases to have a beneficial interest in the shares.
(4)In a case within section 453(1)(b) (company becoming dependent subsidiary after time of acquisition) there is a “chargeable increase” in the value of the shares if the value of the shares at the appropriate time exceeds their value at the time when the company becomes a dependent subsidiary.
(5)In subsection (4) “the appropriate time” means whichever is the earlier or earliest of—
(a)the end of the period of 7 years after the date on which the company becomes a dependent subsidiary,
(b)the time when the employee ceases to have a beneficial interest in the shares, and
(c)if the company ceases to be a dependent subsidiary, the time when it does so.