Q. Re- questions 3258-59 on tattoos. Can one put on tefillin on top of a tattoo or is it a chatzitza (interposition)?
A. On question 542 regarding a woman that became a Baalas Teshuvah and she has a tattoo that she is planning to remove or change, if it is meantime considered a chatzitzah for immersion in a Mikvah; we wrote: “Posikim rule that stains that have no substance to them, and they just present a superficial coloration of the skin, such as an iodine or a weak ballpoint stain, on the onset they should be removed when possible. (Har Tzvi Y.D. 163, Pische Zuta 198: 26, Shiurey Shavet Halevy 198: 17, Chut Shani 198: 23, Pischei Halocho 2: 296).
However in regards to tattoos, Horav Shlomo Miller’s Shlit’a opinion is that she is permitted to immerse without having them excised, since the stain is under the skin.”
The Rov’s opinion is that certainly it is not a chatzitza for Tefillin.
See similar answers in Minchas Yitzchok (3: 11), Alei Siach p. 51 quoting Horav C. Kanievsky Shlit’a, and others.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a