Tattoos in general are not intrinsically evil. However, it could depend on the type of tattoo a person is getting and for what reason. Examples could include racist tattoos or sexually explicit tattoos. Then, they could become sinful.
This question recently came up on the Ask an Expert forum - you can find that thread here: forums.catholic-questions.org/member.php?u=96626. Happy learning! (if you had done a search, you might have missed it, given your spelling of ‘tattoo’ - note the third ‘t’)
**I had a tattooed individual once tell me, when I asked him how did he reconcile being as tattooed as he was with his Faith, and he smiled and said: “My body is a temple of the Lord, but he left it up to me to decorate it.” **
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