Activity While Hearing Kaddish
Question
Answer
Shalom u’verachah
It is forbidden to engage in anything else, and one is obligated to listen and answer.
Even a mitzvah activity such as tzedakah is forbidden.
Source
Mishnah Berurah, siman 25, se’if katan 56
And people who have the practice of folding the tallit and tefillin and placing them in their cases while Kaddish is being recited are not acting properly, for one must concentrate greatly when answering “Amen, yehei shemei rabbah,” as explained below in siman 56 in the Tur and Shulchan Aruch. And “Amen, yehei shemei rabbah” is on an even higher level than Kedushah, as explained there in the Magen Avraham, se’if katan 1, and it is certainly no less than other rabbinic blessings, regarding which it is forbidden to perform even a light activity while the blessing is being recited, as explained below in siman 191 in the Magen Avraham, se’if katan 2:
