Q. May one get a tattoo using ultraviolet ink that can only be seen when it shines under u.v. light?

A. See prior question (# 769) in regards of writing with u.v. or invisible ink on Shabbos. Horav Shlomo Miller’s Shlit”a opinion is that in regards to the prohibition of tattooing, the opinions of the Poskim would be similar, and it would be prohibited at least rabbinically.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a