Zemer after Yom Kippur

"Hamavdil" was originally written to be said on Motzo'ei Yom Kippur in a year that it is also Motzo'ei Shabbos (See חת"ס). It became a zemer used on every Motzo'ei Shabbos, but it is not sung on Motzo'ei Yom Kippur which isn't Motzo'ei Shabbos.

Michael FRBSH

P.S. In a year Yom Kippur falls on Shabbos, we actually sing the first part of the zemer in Ne'illo (after the pizmounim).