Most nonresident students and scholars cannot claim family members as dependents. Any family member who can be claimed as a dependent must have a Taxpayer Identification Number (TIN). If the dependent has been issued a Social Security Number (SSN), it is used as the TIN.
Most family members do not have work authorization, so they may not be eligible to obtain SSNs. The IRS issues an Individual Taxpayer Identification Number (ITIN) to someone who is required to have a TIN but is not eligible to obtain an SSN. The ITIN was created for use on tax returns only.
Those who are permitted to work in the U.S. under their visa status are eligible to be issued a SSN and will not be issued an ITIN for this purpose.