父母移民，入境美國多久可收到綠卡和社安號碼？如何去交$168綠卡手續費（入關時沒人收）？
-Do you mean the immigrant fee? It is $220, not $168. You need to pay this fee online, then USCIS will send the green card to your parents. See this link for the payment:
https://www.uscis.gov/forms/uscis-immigrant-fee
社安號碼要去申請才會有嗎？-Did your parents request SSN card in the DS 260 when they applied for the immigrant visa? If no, they need to appy for it in the loca SSA Office.
要等綠卡到手才能申請嗎？-Not need. Just bring the passport which has the endorsed immigrant visa to apply for it in the local SSA Office.
謝謝解答。
