Why did my order reduce the margin requirement?

The margin requirement for an option spread in a RegT Margin account is rule-based. The margin requirement for an option spread in a Portfolio Margin account is risk-based. More information on US options margin requirements…

For information regarding the margin requirements for options, please visit the Margin page of the IBKR website…

IBKR Singapore offers both cash and margin account types.

All eligible margin accounts employ a risk-based model similar to Portfolio Margin accounts to calculate margin requirements. Please visit the IBKR website…

As a resident of Canada trading stocks you are subjected to Rules-based margin.

The complete margin requirement details are listed in the Margin Requirements section…