A Jew passed away on Kislev 12 5771, before sunset. I told his brother to say kaddish on Kislev 12 5772, which is December 7 night and Dec.8 morning and afternoon 2011. He was told by Bucharian rabbi to have a ceremony On Cheshvan 16, this Sunday Nov. 13 2011, because of the two Adars last year. I phoned that rabbi and was told that they follow the ruling of Harav Ovadia Yosef and Beit Yosef. If a Jewish neshama left this world on Kislev 12,5771… is not the prayer for the departed said on Kislev 12? I am aware that the maximum amount of cleansing is 11 months or less in the World of Truth, but what is the proper answer? Is it Kislev 12 every year or not? Thank you.
The basic halachah for Ashkenazim is that the yahrzeit depends on the date of passing, and not on a 12 month period.
Therefore, the yahrzeit in this case should be observed, as you staed, on Kislev 12.
However, for Sefardinm, many follow the day when 12 months pass, and this is ruled by Rav Ovadyah Yosef (see Yalkut Yosef 40), who nonetheless recommends that both days should be honored.
See Shulchan Aruch, Orach Chaim 568; Yoreh De’ah 402 (end), and Taz and Shach, concerning somebody whose burial was only some days after his passing. See also Penei Baruch, Chap. 39, no. 35-6.