Notwithstanding any other provision of this subchapter, no monthly benefits shall be paid under this section or under section 423 of this title to any individual who is not a citizen or national of the United States for any month which is—

(A) after the sixth consecutive calendar month during all of which the Commissioner of Social Security finds, on the basis of information furnished to the Commissioner by the Attorney General or information which otherwise comes to the Commissioner’s attention, that such individual is outside the United States, and

(B) prior to the first month thereafter for all of which such individual has been in the United States.

For purposes of the preceding sentence, after an individual has been outside the United States for any period of thirty consecutive days he shall be treated as remaining outside the United States until he has been in the United States for a period of thirty consecutive days.