Most individuals use their Social Security number as their taxpayer identification number in the U.S. However, the Social Security Administration limits its assignment of SSNs to individuals who are U.S. citizens and alien individuals legally admitted to the U.S. for permanent residence or under other immigration categories that authorize U.S. employment. For nonresidents to acquire a taxpayer identification number, a nonresident must apply for an international taxpayer identification number, or ITIN.
The ITIN application (Form W-7) requires copies of various identity papers. In a new development, the IRS is now requiring that ORIGINAL documentation accompany the application, such as birth certificates and passports. Notarized copies of documents will not be enough, although certified copies of the required identity documents issued by the issuing agency can also be used.
Some applicants aren't impacted by these interim changes, such as spouses and dependents of U.S. military personnel who need ITINs, and nonresident aliens applying for ITINs for the purpose of claiming tax treaty benefits.