Generally speaking, an alien beneficiary of social security benefits cannot receive benefits if they have remained outside of the United States for six consecutive months. After a beneficiary has been outside the U.S. for thirty consecutive days she is deemed to be continuously outside the U.S. until she has returned to and remained not the U.S. for thirty consecutive days.
Thus, in order to continue to receive benefits, an alien beneficiary generally must either return to the U.S. at least every 30 days or must return to the U.S. for at least 30 consecutive days during each 6 month period.
A United States citizen who remains outside the United States May continue to draw social security benefits to which they may be entitled.
See Social Security Ruling (SSR) 89-12.