We never calculate margin requirements on futures. IB uses requirements set by exchanges and clearing houses. Other brokers do the same as it required by law. We allow 1/2 margin reduction on majority of liquid futures during certain period of time. Other brokers could require less because it is...
Futures margin is actually performance bond requirements. It does not involve money borrowing and it is legal to trade futures and futures options on IRA account. Your loss is your responsibility.
Liquidations are limited by certain time brackets. For example, all US products except some very liquid futures could be liquidated only between 9:40 and 16:00 EST.