You contact for tax identification. Also, can be given for non-work purposes if the law requires you to provide a non-work Social Security number to get a federal benefit or state general assistance benefit that you are otherwise qualified for.
See this info TIN: http://www. .gov/Individuals/International-Taxpayers/Taxpayer-Identification-Numbers-(TIN)
This for SSN: http://ssa-custhelp.ssa