ITEPA03/S446X imposes a charge on the employee if:
In most cases the employee himself will be the “associated person”, but see ERSM20250. The charge arises for the year of assessment in which the disposal occurs, per ITEPA03/S446Y (2).
The amount of charge is:
CD – MV – DA
CD (consideration on disposal) is the consideration given on the disposal,
MV (market value) is the market value of the employment-related securities at the time of the disposal, and
DA (deductible amount) is any expenses incurred in connection with the disposal.
See example computation in ERSM80040.