Question:
I have a Yartzeit on Motzei Shabbos-Sunday. How do I go about accepting it at Mincha Shabbos afternoon? Is it a problem of Hachana? Where can I find this written?
Answer:
You are allowed to be mekabel taanis on shabbos, however you should not say the Yehei Ratzon part, which is a tefilah. As a side point If you usually fast on the day of the yahrtzeit even if you were not mekabel taanis it is as if it already done.
Sources:
Rivivos Efrayim 269(2), Emek Halacha 36. Gesher Hachayim 32-6.
