可靠,正确的做法是让他们到social security administration 去要一份official letter stating this number 123-45-6789 has been assigned to 张三。SSA会issue一份official的letter,上面有SSA的钢印。
他用那social security number给他的employer不等于那number就assign给他了。
I bet they are not able to give you an official letter from SSA.