Art Scroll and Birnbaum (Nusach Ashkenaz) siddurim state that tzidkatcha should not be said on a day when Tachanun would have been skipped had it been a weekday. I believe that similar instructions are indicated regarding saying "El Maleh" for someone's yahrtzeit.
On the rules for Tachnaun, these siddurim indicate that it is not said during Mincha on the day before such occasions.
My question, and confusion regarding the 2nd rule about "day before" aka Erev...
One of the days to omit Tachanun is Erev Rosh Hashanna, and Tachanun is not said during Shacharit either. Since the entire day of Erev Rosh Hashanna has no Tachanun, does that mean that the mincha of the day before that, which is "Erev Erev Rosh Hashanna" also omit tachanun, which, this year would translate to omitting both tzikatcha as well as El Maleh?