Question:
Is there an obligation to go to the Mikvah the morning after having Tashmish? What about on Shabbos?
Answer:
Hello,
What you are referring to is called Tevilas Ezra. Nowadays there is no obligation to go to the mikva, however if possible it is a recommended thing to do, even on shabbos. However when going to the mikva on Shabbos one should be careful not to squeeze out any water from his hair.
Best wishes
Sources:
Orach Chaim 88-1, Mishna Berura 4.
