So I'm no doubt putting the cart before the horse, or whatever the saying is here. Its just that this question has constantly occurred to me as I've reviewed these forums and, while I think I know the answer; I figure someone else here probably knows for sure. So, I get the process... I secure an agent, negotiations occur and ultimately let's say all goes well. Publisher X strikes a deal with my camp and an advance of $5,000.00 is agreed upon, which I then receive. Continuing with the hypothetical situations, let's say my book sells enough copies to make $4,900.00 by the deadline. Does this mean I now owe Publisher X $100.00?