A United States citizen dwelling outside the United States is eligible to vote a federal ballot by mail if:
(1) the citizen's most recent domicile in the United States was in this state and the citizen's intent to return to this state is uncertain;
(2) the citizen would be eligible for registration as a voter in this state if a resident; and
(3) the citizen is not eligible to vote on federal offices in any other state.
Official text of the Texas Election Code as published by the Texas Legislative Council.