The taxable gain for the year of assessment 2020/21 is $0. 

Step-by-step explanation

Hello dear student!

Under Taxation Laws, a taxable gain arises the moment there is a sale of an asset which produces monetary income for the taxpayer. In other words, there is only a taxable gain if there is a sale of an asset. In this case, there was no such sale of the asset as William was forbidden to sell the shares of Tai Fat Ltd. which was awarded to him for a period of one year after the award. Therefore, since there is no sale of an asset at all which occurred here, it follows that William has realized no taxable gain and accordingly, the taxable gain is ZERO ($0) 

Likewise, please take note that the mere award of the shares alone will not suffice to give rise to a gain or income on the part of William as such shares is not money which is what is contemplated by the legal concept of gain and income under tax laws.