Passover 2020 begins at sunset on Wednesday, April 8 and concludes on Thursday, April 18 with the emergence of three stars in the evening.
While the mitzvah of eating matzah and having a Passover Seder applies when the holiday begins (though we really wait until nightfall to recite kiddish and have the Seder), the restrictions of eating and owning chametz in fact begin earlier in the day. Already from late morning on Wednesday, April 8 the prohibitions of chametz apply. Why is the case?
If you look at the Torah’s description of Passover what you find is something extraordinary. The holiday that we know and love is not actually called Passover! It’s called “Chag Hamatzot,” the holiday of matzah. The holiday that is referred to as “Passover” is something else. Passover is a one day holiday, that occurs on the 14th of Nissan. The 14th of Nissan is what we colloquially call Erev Passover, but in fact it’s the real Passover. The 14th of Passover was the date in antiquity when the Passover Lamb was slaughtered and prepared for consumption at the Passover Seder that would occur later that evening. According to the law, chametz can not be consumed during the time that the Passover sacrifice is prepared, and therefore chametz already becomes prohibited on the 14th of Nissan.
So as we prepare to celebrate Passover 2020, let us not forget to properly dispose of, eat or sell our Chametz before the holiday starts.