The trade deadline specifies the point at which no more trades may be acted upon. If a trade is accepted prior to the deadline, it will still go through the approval / veto / completion process. For daily leagues, the deadline is just before midnight ET after the date specified. For weekly leagues, the deadline is just before midnight ET on the Monday after week specified. Please see your league rules for trade rules specific to your league.
Last Updated: 10/19/2011