Can one say vidui in Keriat Shema al HaMitah before midnight?

Shalom,

One says vidui even before midnight, but on all those days on which Tachanun is not recited in prayer, such as Shabbat, Rosh Chodesh, and the entire month of Nissan (the days on which Tachanun is not recited are listed in the siddur before the Tachanun prayer) - one does not say vidui in Keriat Shema al HaMitah. And also on the evening after such days, one who sleeps before midnight does not say vidui in Keriat Shema al HaMitah.

Sources: This is also written by the Chida zt"l in Machazik Berachah (siman 1? Actually original says סימן ש סק"ה) in the name of Maharam Zakut in his responsa, siman 30, that he received this from the Ari zt"l. And see also the Gaon R. Chaim Palagi zt"l in the book Kaf HaChaim (siman 32, seif 64), who wrote in the name of Chesed leAlafim that the same law applies on Motzaei Rosh Chodesh and Chanukah as well.

With blessings,

Hillel Meirs