Tax Identification Number (TIN)
A Tax Identification Number (TIN) is a unique nine-digit identifier used by tax authorities to identify taxpayers and administer the tax system. In the U.S., the Internal Revenue Service (IRS) issues most TINs; Social Security numbers (SSNs) are issued by the Social Security Administration.
Key takeaways
- TINs are nine-digit numbers used to identify individuals and entities for tax and government purposes.
- The IRS issues most UINs in the U.S.; SSNs are issued by the Social Security Administration.
- TINs are required on tax returns, employment forms, credit applications, and many government interactions.
Types of TINs (U.S.)
- Social Security Number (SSN)
- Issued to U.S. citizens, permanent residents, and some temporary residents.
- Format: XXX-XX-XXXX. Required for employment, Social Security benefits, and many government services.
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Important: A child must have an SSN before a parent can claim them as a dependent on a tax return.
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Individual Taxpayer Identification Number (ITIN)
- Issued by the IRS to certain nonresident and resident aliens, their spouses, and dependents who are ineligible for an SSN.
- Format: XXX-XX-XXXX and always begins with a 9.
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Application: Form W-7 and supporting documentation of identity and foreign/immigration status.
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Employer Identification Number (EIN)
- Used by businesses, corporations, partnerships, trusts, and estates for tax reporting.
- Format: XX-XXXXXXX.
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Required to report business income, employment taxes, and other entity-level filings.
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Adoption Taxpayer Identification Number (ATIN)
- Temporary number for children in domestic adoption when an SSN is not yet available.
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Child must be a U.S. citizen or lawful permanent resident and the adoption must be pending.
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Preparer Tax Identification Number (PTIN)
- Required for paid tax return preparers to include on each tax return they prepare.
When a TIN is required
- Filing federal (and often state) tax returns.
- Employment: employers require SSNs to verify eligibility to work and for payroll reporting.
- Credit and lending: lenders and credit agencies use SSNs or other TINs to verify identity and report credit history.
- Business tax filings: businesses use EINs and may also obtain state tax identification numbers.
Who needs a TIN
- Individuals working or filing taxes in the U.S.
- Nonresident aliens and others ineligible for SSNs may need ITINs to comply with U.S. tax laws.
- Corporations, partnerships, trusts, estates, and nonprofit organizations require EINs.
Availability and security
TINs are sensitive personal information. The issuing agency provides official documentation containing the identifier; TINs are not publicly available through online searches and should be protected against identity theft.
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Global perspective
Most countries use tax identifiers. Examples:
* Canada: Social Insurance Number (SIN), nine digits (XXX-XXX-XXX), used for employment, taxation, benefits, and credit.
* European Union: individual member states issue TINs to identify taxpayers and facilitate cross-border investment and tax administration.
TIN vs. SSN
A Social Security number is one type of TIN used primarily for individual identification, employment authorization, benefits, and taxation. Other TINs (ITIN, EIN, ATIN, PTIN) serve specific purposes for noncitizens, businesses, adoptees, and paid preparers.
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Bottom line
TINs are essential for tax compliance, employment, credit, and many government services. Individuals and entities must use the correct type of TIN for filing and reporting, protect the numbers as sensitive data, and obtain the appropriate identifier from the issuing agency when required.