שולחן ערוך אורח חיים · סימן תרס״ז

English

The sukkah and its decorations are forbidden also on the eighth day: The sukkah and its decorations are also forbidden on the eighth day. Outside of Israel, where they do two days of Yom Tov, they are forbidden also on the ninth day, which might be the eighth. If Shabbat falls on the evening after the last day of the holiday, the custom is to not use the decorations until after Shabbat. There are those who are permissive. Rema: There are some who have the custom upon leaving the sukkah of saying "May it be Your will that we merit to sit in the Leviathan's sukkah" (Kol Bo). It is forbidden to prepare on Yom Tov for the next Yom Tov. Therefore, it is forbidden to set up tables and benches in the house in preparation for the evening because this is [illicit] preparation (Hagahot Maimoni and Mahari"l).