Forex Options Margin Policy
The FX option margin calculation does not apply to Touch options, however open positions will affect the amount you have 'Available for Margin Trading' as displayed in the Account Summary.
Therefore, if margin positions are held on the account, the 'Margin Utilisation' will increase when adding Touch option positions.
Note. Before opening the position a pre-check will be done to ensure that you cannot accidentally open a Touch option position that will move the Margin Utilisation above 100%.