Is it permissible to say Tashlich until Shemini Atzeret?

Hello,

The custom of most of the world is to say Tashlich after Mincha on the first day of Rosh Hashanah (see Rema, Orach Chaim, end of Siman 581, and Mishnah Berurah, note 28).

However, those who did not manage to say Tashlich on Rosh Hashanah may do so during the Ten Days of Repentance. There are those who have the custom to always say Tashlich during the Ten Days of Repentance on the "Thirteen Attributes"—that is, one day before Erev Yom Kippur (see the Admor of Monkitsh, zt”l, in the book Sha'ar Yissachar, article Shuva Yisrael, sections 22-23, and in the responsa Divrei Yisrael, part 1, Siman 167, as well as in the book Sha'arei Halacha U'Minhag, additions and supplements, Siman 76).

Best regards,

Hillel Meirs