http://www.interactivebrokers.com/en/trading/marginRequirements/physicalDeliveryLiquidationRules.php
The standard Close-Out Deadline for holders of long positions is the end of the second(2nd) business day prior to the exchange specified First Notice Day.
For holders of short positions, the standard Close-Out Deadline is the end of trading on the second(2nd) business day prior to the exchange-specified last trade day
Certain contracts use a different time ahead of the Close-Out deadline as specified in the following table
To avoid deliveries in expiring futures contracts, customers must roll forward or close out positions prior to a Close-Out Deadline
For futures contracts that are settled by actual physical delivery of the underlying commodity (physical delivery futures), customers may not make or receive delivery of the underlying commodity. Certain currency futures are excepted from this rule (see the table below).