168. How Long to Recite Kaddish

26:17 The custom is to say Kaddish for only eleven months so as not to suggest that one’s parent was an evil person. This is because the evil are judged for twelve months. Therefore, if a person dies on the tenth day of the month of Shevat, Kaddish is recited until the ninth of Teves. Kaddish is not recited on the tenth of Teves, which is the first day of the twelfth month. For this purpose, we count from the burial and not from the date of the deceased passing because one’s judgment does not commence until the burial. Therefore, if one was buried on the eleventh of Shevat, Kaddish stops on the tenth of Teves; in a leap year, Kaddish would stop on the appropriate date in Kislev. On the day the mourner stops saying Kaddish, he is entitled to say all the Kaddishes, though a person with yahrtzeit and a person in Shloshim are each entitled to one, and if there are many such people in shul, the one who is saying Kaddish for the last time may not be left with any to say. If a person’s parent really was evil and would be judged for the full twelve months, then it would be appropriate to say Kaddish for twelve months.

26:18 When there are many mourners in shul, arguments may break out over who has the right to say Kaddish. The practice has therefore arisen to allow multiple people to say Kaddish in unison.