My Father ZTL was niftar on the 19th Av (Tuesday 4th August 2015) in Chutz Laaretz and the Levayah was on 21 Av (Thursday 6th August 2015) in Eretz Yisrael.
When is the:
1 Last day to say Kaddish
2 Last day of Avelius
3 Even though the Yartzeit is in the 13th month(leap year) should one go to the Kever at the end of the 12th Month?
1 On the last day of the eleventh month from the day of the petirah, the 18th of Sivan.
2 On the last day of the 12th month from the petirah, the 18th of Tamuz.
3 Yes, on the final day of the 12th month the custom is to visit the kever [aside from the Yortzeit, see Kav Hayashar Chapter 71].
Rama Y:D 376:4, Baer Heitev O:C 132:5,
Shulchan Aruch Y:D 391:2,
Shulchan Aruch Y:D 344:20