https://secure.ssa.gov/poms.nsf/lnx/0500501410
1. Calendar month requirement
An individual is not eligible for SSI benefits for any month during all of which he/she is outside the United States (U.S.).
2. 30-Day requirement
An individual who was outside the U.S. for 30 consecutive days is not considered in the U.S. until he/she is in the U.S. 30 consecutive days.