The United States uses several forms of unique identification numbers to verify identity for government services, taxation, employment, and financial transactions. This guide explains the main UID options, eligibility, and steps to obtain each one. Readers will learn how to determine which UID fits their needs, what documents are required, and where to apply.
Social Security Number (SSN)
The Social Security Number is the primary personal identifier in the United States. It is used for employment, tax reporting, social security benefits, and many financial transactions. U.S. citizens, permanent residents, and certain noncitizens may be eligible. The process depends on status and location, but generally, applicants submit documentation to the Social Security Administration (SSA). The SSN is assigned while validating identity, age, and lawful work status.
Eligibility hinges on legal work authorization or eligible immigration status. For eligible noncitizens, the SSA issues SSNs after arrival or once authorized to work. Common required documents include a birth certificate or passport, immigration documents, and proof of work authorization. Applicants may apply in person at a Social Security office or, in some cases, online for certain groups. The number itself never changes, but name changes must be updated with SSA.
Key steps to obtain an SSN:
- Confirm eligibility based on immigration and work status.
- Gather required documents: proof of identity, age, and immigration status as applicable.
- Complete the SSA application form (Form SS-5).
- Submit in person or, where allowed, online with supporting documentation.
- Receive your SSN card by mail after verification, typically within a few weeks.
Important: Treat your SSN as highly sensitive. Do not carry the card; memorize the number and store the card securely. Be cautious of scams requesting SSN details.
Individual Taxpayer Identification Number (ITIN)
An ITIN is issued by the Internal Revenue Service (IRS) for individuals who are required to have a U.S. tax ID but are not eligible for an SSN. This includes certain nonresident aliens, their spouses, and dependents. ITINs are used for tax reporting and filing. They do not authorize work in the United States or provide eligibility for Social Security benefits.
To apply, complete Form W-7 and attach documentation proving foreign status and true identity. Acceptable documents include a passport, national identity card, or other government-issued documents. Applications can be submitted with the tax return, or directly to the IRS using accepted submission methods such as mail, or in some cases through an IRS-authorized Acceptance Agent or U.S. Taxpayer Assistance Center.
Common reasons to need an ITIN include filing a U.S. tax return, being claimed as a dependent, or opening a bank account that requires a tax ID. Processing times vary, but applicants should plan for several weeks to a few months, depending on documentation and method of submission.
Employer Identification Number (EIN)
The Employer Identification Number is a business identifier, not a personal one. It is used for tax reporting, opening business bank accounts, hiring employees, and fulfilling regulatory requirements. U.S. businesses, including sole proprietorships, partnerships, LLCs, and corporations, typically apply for an EIN from the IRS.
Requirements depend on business type and ownership changes. The application can be completed online via the IRS EIN Assistant, by phone, or by submitting Form SS-4. Most applicants receive their EIN immediately online, with official confirmation mailed or provided in some cases. Banks and vendors often require an EIN to set up accounts or process transactions.
Application tips include ensuring the business structure is defined, accurately listing the legal name and address, and confirming responsible party information. An EIN never changes even if the business moves or changes ownership, making it a stable identifier for tax and regulatory purposes.
Data-Identification Numbers for Businesses: DUNS
The DUNS number, issued by Dun & Bradstreet, is a widely used business identifier in commercial contexts. It helps verify a company’s existence and creditworthiness for suppliers, government contracts, and large procurement programs. While not issued by a federal agency, a DUNS is commonly requested in U.S. business dealings and is often required for government bids and grants.
To obtain a DUNS number, businesses register on the Dun & Bradstreet website, providing details about the legal name, address, and corporate structure. The process is typically free, and the number is assigned once the business information is verified. Maintaining up-to-date data is essential for accurate credit reporting and eligibility in programs that rely on DUNS.
Best practices for DUNS usage include synchronizing it with the company’s legal name and address, updating it after corporate changes, and linking it to relevant banking and vendor accounts. While distinct from a tax ID, the DUNS number often serves as a trusted external identifier in supplier networks and government portals.
Other Considerations: Real ID and Passport Numbers
For travel within and to the United States, the Real ID credential is an enhanced form of identification tied to a person’s identity documents. It is not a tax or business ID, but it functions as an official identification for domestic flights and certain state services. A U.S. passport number is another federal identifier used for international travel and international banking or residency processes. Neither is intended to replace SSNs or EINs for their core purposes, but they may intersect with identification requirements in specific scenarios.
Applicants should understand which UID is appropriate for their situation. For work and taxes, an SSN or ITIN is typically essential. For business operations, an EIN and possibly a DUNS number are relevant. For travel and government access, Real ID or a passport number may be necessary.
Best Practices For Protecting Your UID
Protecting any UID is critical to prevent identity theft and fraud. General security measures include keeping documents secure, using strong, unique passwords for online portals, monitoring tax and financial accounts, and promptly reporting suspicious activity. Only provide UID information through official channels and verify the legitimacy of requests. When in doubt, contact the issuing agency directly using official contact methods published on their website.
For individuals, limit sharing SSNs or ITINs to essential purposes. For businesses, restrict access to EIN and related data to authorized personnel, and implement robust internal controls. Regularly review credit reports and financial statements to catch discrepancies early.
Where To Apply And Contact Points
SSN applications go through the Social Security Administration, with in-person or online options depending on status. ITIN applications are handled by the IRS with Form W-7. EIN requests are processed by the IRS via Form SS-4 or the online EIN Assistant. DUNS numbers are obtained directly from Dun & Bradstreet. Real ID and passport-related services are managed by federal and state agencies and passport services respectively.
Applicants should prepare to provide verified documentation and confirm eligibility prior to submitting requests. Using official portals reduces the risk of fraud and ensures faster processing times.