Should I do a hefsek tahara at the end of Yom Kippur or wait until the following day? Thanks
Yes, a hefsek tahara can be done on Yom kippur. If you have to wash yourself a little bit in order to do the hefsek, that is also permitted, as it isn’t considered washing for pleasure.
Have a gmar chasima tova
Mishna Berura 613- 31.