Molly S. Usually paid upon booking, assuming contracts are solid and collections are high. That keeps the reward immediate and the rep can move on to the next thing. When an employee leaves, if there is some lead time and you are worried that they won't put in effort towards the end, you can offer commissions on sales that come in 30 days (or 45, 60, etc.) after their last day. That way they keep moving the deals forward.