Can I use tea tree oil while on accutane?

Yes. There should be
no problem using the oil, but try a small area first to make sure that you are
not having any reaction before using it on a larger area

What would you like to use it for?If you're using it as a facial moisturizer, it's probably better to use something more oil free.If it's an ingredient in a moisturizer or soap or anything else you're using, go ahead.  There is no contraindication or problem with tea tree oil and accutane.