If your son resides outside of the United States, there is nothing legally preventing him from being the executor of your estate if that is your desire.However, from a practical aspect having an executor of an estate whose obligations it is to ascertain the assets of a decedent's estate, safeguard them, review creditor's claims, sign paperwork regarding the estate and have the assets distributed can be somewhat difficult to manage.Likewise due to distance factors there can also be delays in getting matters signed such as paperwork associated with the probate of an estate. However, if you want your son as the executor of your estate, he would be a natural choice in that parents typically have one of their children serving as such.Good question.