(1) This section applies where the employment-related securities have been restricted securities or a restricted interest in securities at any time during the relevant period.

(2) DA is to be deducted from the amount determined under section 446L(4) (or, where section 446M applies, the amount determined under sections 446L(4) and 446M).

(3) DA is the aggregate of the amounts arrived at under subsection (4) in relation to each event occurring during the relevant period that is a chargeable event in relation to the employment-related securities.

(4) The amount is—

TA - ARTA

(5) TA is the taxable amount actually determined under section 428 in relation to the chargeable event.

(6) ARTA is the taxable amount which would have been determined under section 428 in relation to the chargeable event if any non-commercial increases during the period—

(a) beginning at the same time as the relevant period, and

(b) ending immediately before the chargeable event,

had been disregarded.

(7) If any of the employment income arising under section 426 by virtue of the chargeable event is foreign securities income within the meaning of section 41C, reduce the taxable amount mentioned in subsection (5) by the amount of the foreign securities income.

(8) If any of the employment income that would have arisen (if the non-commercial interests mentioned in subsection (6) had been disregarded) under section 426 by virtue of the chargeable event would have been foreign securities income (within that meaning), reduce the taxable amount mentioned in subsection (6) by the amount of the foreign securities income.