Learn About Finding Your Tax Identification Number

What Is a Tax Identification Number and Why You Need One

A Tax Identification Number (TIN) is a nine-digit number the Internal Revenue Service (IRS) assigns to individuals and businesses for tax purposes. Think of it as your tax ID card. This number appears on tax documents, W-2 forms, 1099 forms, and other IRS paperwork. The most common type of TIN for individual citizens is the Social Security Number (SSN), which serves double duty as both a Social Security identifier and a tax identification number.

Different types of entities receive different kinds of tax identification numbers. Self-employed individuals and business owners often use an Employer Identification Number (EIN), also called a Federal Employer Identification Number (FEIN). Non-citizens who work in the United States may have an Individual Taxpayer Identification Number (ITIN). Each type of number serves specific purposes within the tax system.

You need a TIN to file income tax returns, open a bank account, apply for credit, or report income from work. Employers use your TIN to report wages to the IRS and Social Security Administration. Landlords and financial institutions use it to track income and assets. Without a TIN, you cannot file taxes or receive many financial services. According to the IRS, over 330 million SSNs and millions of EINs and ITINs have been issued.

The TIN system helps the government track income, ensure tax compliance, and prevent fraud. When you earn money through employment, investments, or self-employment, that income gets reported to the IRS using your TIN. This creates a record that the IRS uses to verify whether you owe taxes and whether you have paid the correct amount.

Practical Takeaway: Your TIN is essential for any financial transaction involving the U.S. tax system. Understanding which type of TIN you need depends on your work status and citizenship. Most U.S. citizens use their Social Security Number as their primary tax identification number.

Understanding the Different Types of Tax Identification Numbers

The Social Security Number (SSN) remains the most common type of TIN for U.S. citizens and permanent residents. A nine-digit SSN is assigned by the Social Security Administration, typically when you are born or when you first enter the country legally. The first three digits historically represented the state where the number was issued, though this changed in 2011. Today, SSNs are assigned randomly. Over 450 million SSNs have been issued since the Social Security program began in 1935.

An Employer Identification Number (EIN) is a nine-digit number assigned to businesses, nonprofits, and certain other entities. Sole proprietors who have no employees may not need an EIN and can use their SSN instead. However, partnerships, corporations, LLCs, and businesses with employees must obtain an EIN. The IRS issues EINs at no cost. According to IRS data, over 30 million active EINs are currently registered in the United States. Many small business owners obtain an EIN even without employees to keep their personal finances separate from business finances.

An Individual Taxpayer Identification Number (ITIN) is issued to non-citizens who need to file taxes but do not have a Social Security Number. This includes certain immigrants, visa holders, and dependents of U.S. citizens who do not have SSNs. The IRS has issued over 17 million ITINs since the program began in 1996. ITINs follow the same nine-digit format as other TINs. To obtain an ITIN, applicants must file Form W-7 with appropriate documentation of identity and residency.

Adoption Taxpayer Identification Numbers (ATINs) and Preparer Tax Identification Numbers (PTINs) serve more specialized purposes. An ATIN is temporary and used when adoptive parents need a tax identification number for a child before adoption finalization. A PTIN is required for all tax return preparers who are paid to prepare tax returns for others. Tax professionals must renew their PTIN annually.

Practical Takeaway: Your situation determines which type of TIN you need. If you are a U.S. citizen or permanent resident, your Social Security Number serves as your TIN. If you own a business, you likely need an EIN. If you are a non-citizen working in the U.S., you may need an ITIN. Understanding which type applies to you helps ensure proper tax reporting and compliance.

How to Find Your Existing Tax Identification Number

If you have a Social Security Number, finding it is often straightforward. Check documents you have received from employers, banks, or the government. Your SSN appears on your Social Security card, which is a plastic card issued by the Social Security Administration. Look in a safe place where you keep important documents. Your SSN also appears on tax documents like W-2 forms from employers or 1099 forms from clients who paid you. If you filed a tax return in previous years, your SSN is listed on that return.

Contact the Social Security Administration if you cannot locate your SSN. You can call 1-800-772-1213 or visit your local Social Security office in person. Bring photo identification and proof of citizenship or legal residency. Processing requests by phone or in-person is free. The Social Security Administration website includes a tool to help you locate your nearest office. Response times vary from several days to several weeks depending on how you submit your request.

For an Employer Identification Number, check any documents related to your business. Your EIN appears on IRS correspondence, bank accounts opened in your business name, and any tax forms filed under the business. Look through past business tax returns or Form 941 documents filed with the IRS. Contact the business accountant or previous owner if you have taken over an existing business.

The IRS provides a method to retrieve your EIN if you have lost it. Call the Business and Specialty Tax Line at 1-800-829-4933 during business hours. Have your business name, address, and responsible party information available. The IRS can confirm your EIN over the phone. You can also search for your business EIN online through the IRS's Tax Professional Online Services if you are a representative of the business.

If you have an ITIN and need to find it, check your Form W-7 approval notice, which the IRS sent when your ITIN was issued. Look for your ITIN on any tax returns you have filed or correspondence from the IRS. If you cannot locate your ITIN, contact the IRS at 1-800-829-1040 with your personal information and identification documents ready.

Practical Takeaway: Search your personal records and financial documents first before contacting government agencies. Most people can find their TIN within their existing paperwork, saving time and effort. If records are truly lost, the Social Security Administration and IRS have systems in place to help you locate or confirm your number.

Steps for Obtaining a Tax Identification Number When You Don't Have One

U.S. citizens born in the United States receive Social Security Numbers as infants, typically within the first few weeks of life. However, if you were not assigned an SSN at birth, you can request one as a child or adult. Visit your local Social Security office with proof of citizenship, such as a birth certificate or passport. The Social Security Administration also accepts applications by mail. Form SS-5 is the official request form. Processing takes several weeks. There is no charge to obtain a Social Security Number.

Permanent residents and certain visa holders can also obtain a Social Security Number. You must have work authorization and be at least 18 years old in most cases. Visit a Social Security office with your green card or Employment Authorization Document and passport. Bring completed Form SS-5. The same timeline and no-cost policy applies. According to the Social Security Administration, immigrants make up a significant portion of new SSN applicants each year.

Non-citizens without work authorization who need a tax identification number should pursue an ITIN. File Form W-7 with the IRS. Include your Form W-7, proof of identity (passport or national ID), proof of residency in the United States (lease, utility bill, or insurance policy), and any tax returns you are filing. You can mail this package to the IRS address shown on the form or submit it through an IRS-authorized acceptance agent, such as some tax preparation offices or notary services. Processing typically takes 6-10 weeks by mail.

For business owners ne