Schedule 4 Company Share Option Plan (CSOP): General: Foreign currency shares
The market value (MV) of a share under option is calculated when the option is granted. It is not recalculated at current values when later grants take place. If an option is granted with the exercise price denominated in a currency other than pounds sterling, then it needs to be converted into pounds sterling at the exchange rate prevailing on the date of grant (or such other date that HMRC has agreed can be used to determine the exercise price) in order to ensure that the £30,000 limit is not exceeded, an example of such a calculation is provided for guidance - Limit calculation example Word 27KB.
If the market value of an option is converted, at the date of grant, to sterling from another currency for the purpose of deciding whether it is within the paragraph 6 limits when it is granted, it is not recalculated at the exchange rates current at the time of a subsequent grant.