Before revision:  The principal controls the agent's utility over time. Optimal mechanisms keep the agent only just willing to disclose promptly. In an important case, a deadline mechanism is optimal : absent disclosure, the agent enjoys an efficient utility before a deadline, and an inefficiently low utility afterwards. In general, optimal mechanisms feature a (possibly gradual) transition from the former to the latter. Even if monetary transfers are permitted, they may not be used .
After revision:  The principal controls the agent's utility . We uncover a striking deadline structure of optimal mechanisms: they have a simple deadline form in an important special case, and a graduated deadline structure in general .