221:2 One always fasts on the yahrtzeit, even in the first year. This is so even if the time of the deceased’s passing was at the end of the day after they said maariv; if it was still daytime, it is set as the day of the yahrtzeit. However, if the burial was delayed until several days after the deceased’s passing, one fasts on the anniversary of the burial the first year and on the yahrtzeit in subsequent years.
221:3 If the deceased passed away in a leap year, in either the first or the second Adar, then in a regular year the survivor fasts in the one Adar; in a leap year, he fasts in the same Adar in which the deceased died. If he died in the first Adar, the fast is in the first, and if he died in the second Adar, then the second. If the deceased passed away in the Adar of a regular year, then in a leap year the survivor fasts in the first Adar. In the second Adar he says kaddish, but not if doing so will take it away from someone else. (Editor’s note: formerly, only one person would say kaddish.)