In the Know: US Social Security Numbers and Individual Taxpayer Identification Numbers

When dealing with the US Internal Revenue Service (IRS), banking, credit, buying or renting property, or working in the US, you may quickly find that you are asked for a Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN). While the SSN and ITIN can both be utilized for tax filings with the IRS, they are not the same and have different eligibility requirements and application processes.

Eligibility and Applicant Processes for an SSN:

Generally, SSNs are available to US Citizens and Lawful Permanent Residents (LPR).  Furthermore, noncitizens holding nonimmigrant statuses are only eligible for an SSN if they are authorized to work in the United States by the Department of Homeland Security (DHS).

Most first-time SSN applicants may submit their application for an SSN (along with the applicable supporting documents) via mail (from inside the US) or in person at a local Social Security Office in the US (see SSA applications may no longer be submitted at US Consulates and Embassies, except for those applying for immigrant visas (part of Consular Processing/Lawful Permanent Residence).

Certain spouses of employment-based nonimmigrant status holders, including L-2 and E-2D nonimmigrant status holders, are eligible to apply for an Employment Authorization Document and an SSN through one application submission to US Citizenship and Immigration Services (USCIS).

If an individual was previously issued a SSN, but have lost the card, they may be able to apply for a replacement card online (see

Eligibility and Applicant Processes for an ITIN:

Most importantly, if an individual is eligible for an SSN, they are not eligible for an ITIN.

An ITIN is a tax processing number only available for certain nonresident and resident aliens, their spouses, and dependents who cannot get a Social Security Number (SSN). Generally, SSNs are available to US Citizens and LPRs.  US Citizens and LPRs are not eligible for an ITIN.

ITINs may be obtained via one of the following three methods:

  1. By mailing W-7, tax return, proof of identity, and foreign status documents to:

Internal Revenue Service

Austin Service Center

ITIN Operation

P.O. Box 149342

Austin, TX 78714-9342

  1. Applying in person using the services of an IRS-authorized Certifying Acceptance Agent (see
  2. Making an appointment and applying in person at a designated IRS Taxpayer Assistance Center (see

If you have questions abouts SSNs, ITINs, or other cross-border tax or immigration matters, please reach out to the Moodys Tax team.