What Your IRS Number Is and Why You Need It

Your IRS number is the unique identifier the Internal Revenue Service uses to track your tax account

The IRS assigns you a number so they can match your tax returns, payments, and account history to you specifically. For most people, that number is your Social Security Number (SSN). If you don't have an SSN — because you're not a U.S. citizen or don't work — the IRS issues an Individual Taxpayer Identification Number (ITIN) instead. Both serve the same purpose: they let the IRS know whose return is whose, and they're required on every tax document you file.

You may also encounter an Employer Identification Number (EIN) if you run a business, hire employees, or operate as a partnership or corporation. An EIN is a nine-digit number that identifies your business entity to the IRS, separate from your personal tax number. The IRS uses it to track business income, payroll taxes, and employment records.

Key Takeaways

Your Social Security Number is your IRS number if you're a U.S. citizen or permanent resident with work authorization.
An Individual Taxpayer Identification Number (ITIN) is issued by the IRS to people who cannot get an SSN but need to file taxes or report income.
An Employer Identification Number (EIN) is a separate nine-digit number used to identify a business to the IRS, not a personal tax number.
You need your IRS number on every tax return, W-2 form, 1099 form, and when opening certain bank or investment accounts.

Social Security Number as your primary IRS identifier

If you were born in the United States or are a lawful permanent resident with work authorization, your Social Security Number is your IRS number. The SSN is a nine-digit number issued by the Social Security Administration, and it's the number you use on your tax return, W-2 forms from employers, and 1099 forms from banks or contractors who pay you.

The IRS cross-references your SSN with Social Security records, your employer's payroll reports, and financial institutions to verify your income and tax liability. When you file a return, the IRS matches it to your SSN to see if it lines up with what they've already received about you from other sources.

You receive your SSN when you apply for one, usually as an infant or when you first become may be able to access to work. If you've lost your Social Security card, you can request a replacement from your local Social Security office or online at ssa.gov — the IRS doesn't issue replacements.

Individual Taxpayer Identification Number for non-citizens

An ITIN is a nine-digit tax identification number the IRS issues to people who are required to file a U.S. tax return but don't have and can't get a Social Security Number. This includes nonresident aliens, certain visa holders, and undocumented immigrants who earn income in the United States.

You request an ITIN by filing Form W-7 with the IRS. You'll need to provide proof of identity and proof of residency or work status — the specific documents depend on your visa category or immigration status. The IRS processes Form W-7 applications and mails your ITIN to you; the process typically takes four to six weeks, though it can be longer during tax season.

Once you have an ITIN, you use it on your tax return exactly as you would an SSN. You report income, claim deductions, and file returns using your ITIN. The IRS tracks your account under that number, and employers or financial institutions will ask for it on W-2s and 1099s.

Employer Identification Number for business owners

An EIN, also called a Federal Employer Identification Number (FEIN), is a nine-digit number the IRS issues to identify a business. You need an EIN if you operate as a sole proprietor with employees, form a partnership, create a corporation or LLC, or run certain types of nonprofits or trusts. Even if you're self-employed with no employees, you may choose to use an EIN instead of your SSN for business purposes.

You request an EIN by filing Form SS-4 with the IRS online, by phone, by fax, or by mail. Online applications are processed immediately, and you receive your EIN the same day. If you apply by phone, mail, or fax, the IRS typically issues your EIN within four business days.

Your EIN is separate from your personal tax number. If you're a sole proprietor, you still use your SSN or ITIN on your personal tax return; the EIN is used only for business filings, payroll tax returns, and business bank accounts. If your business is a corporation or LLC, the EIN becomes the primary identifier for that entity.

Where you'll need to provide your IRS number

You provide your IRS number (SSN, ITIN, or EIN) on every tax return you file, including Form 1040 for personal income tax and Form 1120 for corporate returns. Employers ask for your SSN or ITIN on Form W-4 when you start a job, and they report your wages to the IRS using that number on your W-2.

Banks, investment firms, and credit card companies ask for your SSN or ITIN when you open an account. They use it to report interest income, dividends, and other earnings to the IRS on 1099 forms. Contractors and freelance platforms ask for your SSN or ITIN before they pay you, so they can issue a 1099-NEC or 1099-MISC.

If you're applying for a mortgage, car loan, or credit card, the lender will ask for your SSN to check your credit history. Government programs, state tax agencies, and child support enforcement also use your SSN to track your account and verify your identity.

How to find your IRS number if you've lost it

If you've lost your Social Security card, you don't need to contact the IRS — you contact the Social Security Administration. You can request a replacement card online at ssa.gov, by phone at 1-800-772-1213, or in person at your local Social Security office. You'll need to show proof of identity and citizenship or lawful residency.

If you've lost your ITIN, you can look it up by filing Form W-7 again or by contacting the IRS directly. The IRS can confirm your ITIN if you provide your name, date of birth, and country of birth. You don't need to request a new one unless yours has expired.

If you need your EIN, you can look it up on IRS.gov using your business name and address, or you can contact the IRS Business and Specialty Tax Line at 1-800-829-4933. Keep a record of your EIN in a safe place — you'll need it for future business filings and bank accounts.

Frequently Asked Questions

Is my Social Security Number the same as my IRS number?

Yes, for most people. Your Social Security Number is your IRS number if you're a U.S. citizen or permanent resident with work authorization. The IRS uses your SSN to identify you and track your tax account. If you don't have an SSN, the IRS issues an ITIN instead, which serves the same purpose.

Do I need an EIN if I'm self-employed with no employees?

No, you don't need an EIN to file taxes as a self-employed person. You can use your Social Security Number or ITIN on your Schedule C and pay self-employment taxes. However, some self-employed people choose to get an EIN to keep their business finances separate from their personal finances, or to open a business bank account.

What happens if I file a tax return with the wrong IRS number?

The IRS will likely reject the return or match it to the wrong account. If you realize you've made an error, contact the IRS immediately. You can file an amended return using Form 1040-X with the correct number. The IRS may also contact you if they notice a mismatch between your return and the income reports they've received from employers or financial institutions.

Can I use my ITIN to open a bank account?

Yes, many banks accept an ITIN as a tax identification number for opening a checking or savings account. Some banks may ask for additional documentation, such as a passport or state ID. Call ahead to confirm your bank's policy before you visit.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.