For interview

If you wear formal dresssing to interview, the suit/shirt should be enough to cover the tatoo at your back. The most important point is that you should have confident to answer all the questions. You should do a research of the company to know its background before you attend the interview. Remember eye focus with the interviewer and present yourself in a mature way.

Try to cover up your tatoo, unless you are looking for a job at a tatoo shop!

Dress for success! Black suit + White shirt

By the way, a tatoo in the back of where?

on your back?

Good Luck on your interview!