How old does a child need to be to be adopted without the non custodial parent's consent?

That would all depend upon what state you are in, what are the circumstances surrounding the adoption. Has the parental rights of natural parents been terminated? In Oklahoma if the child is under the age of 18, a natural parent has to be notified of adoption proceedings. That would all depend upon what state you are in, what are the circumstances surrounding the adoption. Has the parental rights of natural parents been terminated? In Oklahoma if the child is under the age of 18, a natural parent has to be notified of adoption proceedings.