Currency conversions of trading costs as well as profit and loss from trading activities are done using the mid-spread FX Spot rate when you close the position, plus/minus 0,5%. For FX Options the rate is plus/minus 0,1%.
The Currency Conversion fee does not apply to margin collateral. Only settlement of actual payments to or from the trading account are included, for example, buying/selling cash Stocks, paying/receiving option premium or commission etc.
The rate used for currency conversion of amounts booked to your account is shown on the position details in the “open positions” or the day after under the “Trades Executed” report in the “account” section.