Overseas ESOP

Hello HMRC. A company has offered me options under an ESOP. The company and ESOP I are based overseas. Options will vest after certain milestones. At which point in time am I liable for income tax? Is it after the shares vest, or after I exercise the actual options and redeem the shares?

Also I am a UK tax resident

Hi DA Hill,
ESOPs are treated as a perquisite or benefit someone enjoys on account of their job or position and are taxable as income, and are taxable (if owned by a UK resident) when exercised.
If the shares are sold in the market, any profits arising will be subject to Capital Gains Tax.
Tax and Employee Share Schemes
Thank you.