1,091. Chometz She'Avar Alav HaPesach

Chometz u’Matzah 1:3

One does not receive lashes for possessing chometz unless he purchased it on Passover or caused the leavening to occur, in which case he violated actively rather than passively. If one possessed chometz before Passover and he simply neglected to destroy it and kept it in his possession, then even though he violated two Torah prohibitions, he does not receive lashes because he did not perform any action. He does, however, receive the stripes that are administered for acting rebelliously.

Chometz u’Matzah 1:4

It is prohibited forever to derive benefit from chometz that a Jew possessed on Passover. This is a rabbinically-instituted penalty; since one violated the Torah prohibitions against possessing chometz, the Sages prohibited it ever being used. This applies whether one possessed chometz on Passover due to an oversight on his part or under compulsion, as a precaution against the possibility of retaining possession of chometz over Passover in order to benefit from it after Passover.