A stock option lets an eligible recipient buy shares at an agreed exercise price. Exercise gain and later sale gain are separate events.
What an option is
A grant gives a right, not an obligation, to acquire shares under its terms. Read the grant agreement for price, number of shares, vesting, exercise period and what happens after leaving.
From grant to sale
Grant, vesting, exercise and eventual sale are separate stages. The market value used for tax at exercise can differ from later sale proceeds, especially for unlisted shares.
Exercise gain
Reference formula: (market value per share on exercise day − exercise price per share) × shares exercised. If market value does not exceed exercise price, the calculator treats exercise gain as zero.
Employment status and tax
Exercise during employment may be treated as employment income; after leaving it may be other income under the cited rule. A later share sale can create a separate capital gain and tax question.