Q: What are the responsibilities of a guardian for chametz on Pesach?

A: The owner of the chametz violates the prohibition of possessing chametz, even if it is entrusted to another. In addition, the guardian also violates the prohibition of possessing chametz if he accepted responsibility for it, even if it belongs to a gentile (O.C. 440:1; Mishnah Berurah 443:14).

If neither the owner nor the guardian sold the chametz, it becomes prohibited and has to be destroyed. Therefore, if the owner hasn’t sold the chametz, the guardian should sell it in time, both to avoid the prohibition and to prevent the loss (C.M. 292:17-18; O.C. 443:2).

There is a dispute whether the guardian carries legal liability if he neglected to sell the chametz. Some say that the guardian is considered negligent, so even a shomer chinam is liable; some say that only a shomer sachar is liable, since he has a greater responsibility to protect the item. Many maintain that the guardian is not liable, because he accepted responsibility only to guard the chametz, not to sell it. [It is questionable whether this logic would apply nowadays, when it is customary to sell the chametz before Pesach and buy it back afterwards.]

(See Mishnah Berurah 443:12; Pischei Choshen, Pikadon 2:[103].)