Alien Registration Number
An Alien Registration Number, also known as an A-Number, is a unique seven-, eight-, or nine-digit number assigned to a noncitizen by the Department of Homeland Security. It is used to track immigration files for immigrants and some nonimmigrants and is a critical piece of information when preparing new USCIS forms to request immigration benefits. Every immigrant gets a unique number, which they keep for life. The A-Number is found on various documents from U.S. Citizenship and Immigration Services (USCIS) or the former INS, such as the immigrant visa, green card, or Employment Authorization Document. It is used as a form of identification and is required when filling out all immigration forms. Non-U.S. citizens who are in the United States temporarily, such as on a business or tourist visa, typically do not receive an Alien Registration Number.
