ITIN, individual taxpayer identification number (ITIN for short), namely individual tax number, is a tax declaration number specially set by the US Federal Taxation Bureau for non-US citizens who have no SSN social security number but need to file tax returns. Like SSN, the personal tax number is nine digits. It should be noted that having ITIN does not mean that you can work legally in the United States, nor can you enjoy social welfare in the United States. It can be said that the role of ITIN is only to file tax returns for individuals without SSN.