Chametz Found During or After Pesach
According to Halakhah, if chametz is found during Yom Tov, it must be covered over until Chol HaMoed when it can be burned. Chametz found during Chol HaMoed should be burned immediately.
After the holiday, there is a special law known as "chametz she'avar alav haPesach," chametz that was owned by any Jew during Pesach. Such chametz can only be burned; no benefit may be derived from it at all, not even by selling it to a non-Jew.
Chametz that was owned by a Jew during Pesach may not be eaten by Jews after Pesach. If a store owned by a Jew is known not to have sold its chametz, no Jew may buy chametz from that store until enough time has passed that it can be assumed the inventory has changed over since Pesach.
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