Negative carryover is a clause in an affiliate agreement that dictates a negative commission balance when a referred players wins big. Since Revenue share is based on casinos profit from a player, if that player hits a massive jackpot or has a lucky streak the revenue for that month becomes negative. The negative balance is rolled over into the following month until the players future losses have been paid back. That's why many affiliates prefer No Negative Carryover( NNCO) deals, it is like starting every month with a fresh slate, no matter how big wins the player has received the month before.