The absolute deadline for eating chametz is the morning before Passover, two
"seasonal hours" before midday (a "seasonal hour" is 1/12 of the time between
daybreak and nightfall). Click here to obtain the precise time for your
location.
Past this time, is it forbidden to eat chametz until the close of the festival
in eight days. You still have one more hour in which you can use chametz for
non-eating purposes, and handle the chametz in order to sell it or destroy it.