In the United States, your tax file number plays a critical role in how you interact with the Internal Revenue Service (IRS), file your taxes, open a bank account, or even apply for a job. Although the term “tax file number” is more commonly used in countries like Australia, in the U.S., the equivalent is your Taxpayer Identification Number (TIN)—a broad category that includes your Social Security Number (SSN), Employer Identification Number (EIN), and Individual Taxpayer Identification Number (ITIN).
Knowing your tax identification number and understanding which type you need is vital, whether you’re a citizen, resident, nonresident, business owner, or foreign national. This article offers a complete, U.S.-specific guide to tax ID numbers, helping you understand what they are, how to get one, how they’re used, and what to do if you lose or need to recover your number.
What Is a Tax File Number in the U.S.?
In the American tax system, there is no official document called a “tax file number,” but the term informally refers to any number that identifies you for tax purposes. These are officially known as Taxpayer Identification Numbers (TINs) and are issued by either the IRS or the Social Security Administration (SSA).
The TIN is a unique number that the government uses to track your income, tax reporting, and benefits. Everyone who pays taxes in the United States needs one, regardless of whether they are a citizen, a green card holder, or a foreign national earning U.S. income.
There are several types of TINs in the U.S., each used in different contexts depending on your legal status and the type of activity you’re involved in.
Types of Tax Identification Numbers (TINs)
The U.S. tax system recognizes several forms of TINs. Understanding the differences helps ensure you’re using the correct one for your situation.
The most common TINs include:
Social Security Number (SSN)
A Social Security Number is issued by the SSA and is the most commonly used TIN for U.S. citizens and permanent residents. It is a 9-digit number in the format XXX-XX-XXXX. SSNs are used to track lifetime earnings, eligibility for Social Security benefits, and income tax filing.
You must have an SSN to:
● File individual income taxes
● Be employed in the U.S.
● Claim government benefits
● Receive Social Security or Medicare
If you were born in the U.S., your SSN is usually assigned at birth. If you’re a lawful permanent resident or newly naturalized, you’ll apply for one through the SSA.
Individual Taxpayer Identification Number (ITIN)
ITINs are issued by the IRS to individuals who are not eligible for a SSN but need to pay taxes in the U.S. These include non-resident aliens, undocumented immigrants, spouses or dependents of U.S. residents, or foreign investors.
ITINs are also 9-digit numbers but always begin with the number 9. They cannot be used for work purposes or to receive Social Security benefits, but they do allow individuals to:
● File tax returns
● Pay income tax legally
● Claim dependents
● Open a bank account (in some cases)
Employer Identification Number (EIN)
An EIN is assigned by the IRS to businesses and organizations for tax filing and employer purposes. It’s like a Social Security Number for companies. An EIN is necessary if you:
● Own a business with employees
● Operate as a partnership or corporation
● File excise, employment, or alcohol/tobacco/firearm tax returns
EINs are also required to open a business bank account or apply for business licenses.
How Do I Find My Tax File Number (TIN)?
Your TIN is typically listed on important tax documents. If you’re unsure what yours is, the method of finding it depends on the type:
● If you have an SSN, it’s found on your Social Security card, tax return, W-2 form, or official government correspondence.
● If you have an ITIN, it will appear on your IRS ITIN approval notice (CP565) or on your tax return (Form 1040).
● If you have an EIN, it will appear on the confirmation letter you received from the IRS (Form CP-575), or your business tax filings.
If you’ve lost your TIN, you can recover it:
● SSN: Contact the Social Security Administration or check your old tax returns.
● ITIN: Call the IRS at 1-800-829-1040.
● EIN: Request a transcript from the IRS or search your business records.
How Are Tax File Numbers Used in the U.S.?
A TIN is necessary for a wide range of financial and legal activities. The IRS uses it to track your income and tax obligations. Employers use it to report your earnings. Banks and other financial institutions report interest or dividends tied to your TIN. The Social Security Administration uses it to track eligibility for benefits.
Here are some common uses:
● Filing federal and state tax returns
● Reporting wages and paying employment taxes
● Receiving income such as freelance payments, rental income, or investment earnings
● Opening a bank account or applying for credit
● Claiming tax benefits, credits, or deductions
● Proving identity to government agencies
Without a TIN, you cannot legally earn income or file taxes in the U.S., and you may face penalties for noncompliance.
How to Apply for a TIN (Tax File Number)
For a Social Security Number
Apply through the Social Security Administration. If you’re a U.S. citizen, you usually receive an SSN at birth. If you’re an immigrant, you’ll apply using Form SS-5 along with documentation of your immigration status and identity.
For an ITIN
Use IRS Form W-7 to apply for an ITIN. You must submit this form along with your federal income tax return and original identity documents or certified copies. You can also apply through an IRS-authorized Acceptance Agent.
For an EIN
Apply online via the IRS EIN Assistant, or use Form SS-4 and submit it by mail or fax. You must be a responsible party for the business (e.g., owner or officer).
The application process is free and you’ll usually receive your EIN immediately if applying online.
How Long Does It Take to Get a TIN?
● SSN applications take approximately 2–4 weeks.
● ITINs can take 7–11 weeks, or longer during tax season.
● EINs issued online are often delivered immediately, but paper applications can take 4–6 weeks.
It’s crucial to apply early if you’re starting a new job or business or need to file a tax return before the deadline.
Common Mistakes to Avoid
One of the most common issues people face is using an incorrect TIN when filing taxes. This can result in rejected returns, delayed refunds, or penalties. Double-check all documents to ensure accuracy, especially if your TIN includes similar digits to another family member.
Another mistake is delaying your application, particularly for ITINs. Since the IRS often requires original documents, failing to plan ahead can cause serious delays during tax season.
Lastly, avoid sharing your TIN unnecessarily. Identity thieves can use your TIN to commit fraud, so keep this information secure and only share it with trusted, verified entities.
Conclusion
While the phrase “tax file number” may not be commonly used in the United States, the equivalent—your Taxpayer Identification Number (TIN)—is an essential part of your financial identity. Whether it’s your SSN, ITIN, or EIN, your TIN serves as a key that opens the door to legal employment, tax compliance, and full participation in the U.S. financial system.
Understanding the different types of TINs, when and how to use them, and how to keep them secure is vital for every individual and business operating in the U.S. tax system. Whether you’re a new immigrant, a contractor, or a business owner, obtaining and correctly using the appropriate tax file number is one of the first and most important steps toward financial and legal compliance in America.
FAQs
What’s the difference between an SSN and an ITIN?
A SSN is for U.S. citizens and authorized immigrants with work eligibility. An ITIN is for individuals who are not eligible for an SSN but need to file a tax return or report income.
Can I work with an ITIN?
No. An ITIN does not authorize employment in the U.S. It only allows individuals to file taxes or receive certain financial services.
Is an EIN the same as a business license?
No. An EIN is a federal tax ID for your business. A business license is issued at the local or state level and permits you to operate legally in that area.
Can I have both an SSN and an EIN?
Yes. An individual can have an SSN for personal use and an EIN for their business activities.
How do I replace a lost SSN card?
You can request a replacement through the SSA’s website or by visiting a local SSA office with proper identification.
