What Does ITIN Stand For? Complete Explanation

ITIN stands for Individual Taxpayer Identification Number. It is a 9-digit tax processing number issued by the Internal Revenue Service (IRS) to individuals who have a US tax filing obligation but are not eligible for a Social Security Number (SSN). The ITIN was created in 1996 under the authority of Internal Revenue Code (IRC) Section 6109. It is used exclusively for federal tax reporting.

TIN stands for Taxpayer Identification Number and is an umbrella term that includes multiple types: SSN (Social Security Number), ITIN (Individual Taxpayer Identification Number), EIN (Employer Identification Number), ATIN (Adoption Taxpayer Identification Number), and PTIN (Preparer Tax Identification Number). ITIN is one specific type of TIN. When someone says 'TIN,' they could mean any of these. When they say 'ITIN,' they mean specifically the number for non-SSN-eligible individuals.

You need an ITIN if you have a US tax obligation but cannot get an SSN. This includes: non-resident aliens required to file a US tax return, dependents or spouses of US citizens/residents who are claimed on a tax return, non-resident aliens claiming tax treaty benefits, foreign individuals with US business income, and non-residents with US rental property income. Approximately 4.4 million people actively use ITINs in 2026.

No. An ITIN does not authorize employment in the United States. It does not provide eligibility for Social Security benefits, Earned Income Tax Credit (for the ITIN holder), or any immigration status change. An ITIN is exclusively a tax identification number. Work authorization is determined by immigration status and documents like an Employment Authorization Document (EAD), not by tax IDs.

I = Individual (the number is assigned to a single person, not a business). T = Taxpayer (the holder has a US tax obligation or need). I = Identification (the number serves as an identifier in IRS systems). N = Number (the actual 9-digit number in format 9XX-XX-XXXX). Together, ITIN identifies a single person for US tax purposes who does not have and cannot obtain a Social Security Number.

ITIN is one type of tax ID number. In casual usage, people often say 'tax ID' to mean any taxpayer identification number. For individuals, the two main tax IDs are SSN and ITIN. For businesses, the main tax ID is the EIN (Employer Identification Number). When a form asks for a 'tax ID number' or 'TIN,' you can enter either your SSN or ITIN. Both serve the same function for tax filing purposes.

ITIN is pronounced as individual letters: I-T-I-N ('eye-tee-eye-en'). It is not pronounced as a word ('it-in'). In Spanish-speaking communities, it is commonly referred to as 'numero ITIN' or simply 'ITIN.' Some people informally call it an 'ITIN number,' though technically that is redundant since the N already stands for Number. Government officials and tax professionals always spell it out as I-T-I-N.

The IRS created the ITIN system in 1996 to ensure tax compliance for individuals who have US tax obligations but cannot obtain SSNs. Before 1996, non-SSN-eligible individuals had no standardized way to file US tax returns. The ITIN was authorized under IRC Section 6109, which requires every person who files a tax return to include a taxpayer identification number. Since 1996, the IRS has issued over 5.5 million ITINs.

Many countries have similar taxpayer identification systems. Canada has the SIN (Social Insurance Number) for residents and the ITN (Individual Tax Number) for non-residents. The UK uses the NIN (National Insurance Number) and UTR (Unique Taxpayer Reference). Australia has the TFN (Tax File Number). India uses the PAN (Permanent Account Number). Each country's system serves the same purpose: identifying individuals for tax purposes.

No. Businesses need an EIN (Employer Identification Number), not an ITIN. An ITIN is for individuals only. However, the owner of a sole proprietorship can use their ITIN on Schedule C of their personal tax return. LLCs, corporations, and partnerships need their own EIN. You can apply for an EIN using your ITIN as the responsible party's taxpayer ID. See our ITIN vs EIN guide for details.