Can I reuse the option premiums of bought FX options?
As long as you only hold bought FX Options no margin is required. A part of the bought option premium can be reused for further margin trading. The part of the bought option premium that cannot be reused for margin trading is deducted under Not available as margin collateral.
In these cases, the Not available as margin collateral is the minimum of either:
The margin requirement on the option (Delta-Vega margin for the long FXO position as it would have been applied if the bought FX option was part of a portfolio on Delta-Vega margining)