How old do you have to be in order to have bunion surgery?

Depends on deformity. Decision to perform surgery depends on a variety of factors. If they bother on a regular basis or limit activity, it is time to consider surgery. Good shoes with support can slow down the process and poor shoes can speed up and/or aggravate the problem. See your podiatrist to discuss options. Visit Dr l.
There isn't . Necessarily an age. The concern in a child/young person is they have open growth plates or bones that are still growing. You do not want to disrupt these growth plates.