Under federal law, 529 funds can be used at any "eligible educational institution." This definition includes foreign schools, as long as they are approved by the U.S. Department of Education (DOE). The DOE maintains a list of schools eligible to receive student financial aid. If a foreign school appears on this list, it is considered to be an eligible institution under federal rules.

But there's a catch. States aren't required to follow federal eligibility rules (though most do). So there's a chance that your child won't be able to use his 529 funds at a foreign school if a state's plan does not allow it. Check with the administrator of the plan if your child is interested in attending school overseas.