What Your Tax ID Is and Why You Need It

Your tax ID is a nine-digit number the IRS uses to identify you for tax purposes

A tax ID is an identification number assigned by the Internal Revenue Service (IRS) to track your tax records. The most common type is a Social Security Number (SSN), which you get from the Social Security Administration. If you don't have an SSN or cannot get one, the IRS issues an Individual Taxpayer Identification Number (ITIN) instead. Both serve the same purpose: they let the IRS match your income, deductions, and tax payments to your file.

You need a tax ID to file a tax return, report income to employers, open a bank account, or get a mortgage. Without one, the IRS cannot process your return, and employers cannot report your wages. If you work, your employer will ask for your tax ID on your first day — they use it to file a W-2 form at the end of the year.

Key Takeaways

A Social Security Number (SSN) is the most common tax ID; an ITIN is issued to people who cannot get an SSN.
Your employer needs your tax ID to report your wages and file a W-2 at year-end.
You can find your SSN on your Social Security card, tax returns, or W-2 forms from previous years.
If you have never had an SSN or ITIN, you must request one from the Social Security Administration or IRS before you can file taxes or work.
Your tax ID is different from your driver's license number, passport number, or any other government ID.

Social Security Number versus ITIN

A Social Security Number is issued by the Social Security Administration to U.S. citizens, permanent residents, and certain temporary visa holders. It is a nine-digit number formatted as XXX-XX-XXXX. You receive an SSN automatically when you are born if a parent applies for one, or you can request one at any Social Security office. An SSN qualifies you for Social Security benefits, Medicare, and other federal programs in addition to serving as your tax ID.

An Individual Taxpayer Identification Number (ITIN) is issued by the IRS to people who are not may be able to access for an SSN but need to file taxes or report income. This includes nonresident aliens, undocumented immigrants, and some visa holders. An ITIN is also nine digits and looks like a tax ID to the IRS, but it does not make you may be able to access for Social Security benefits or most federal programs. You request an ITIN by filing Form W-7 with the IRS; the process takes four to six weeks.

Both numbers work the same way for tax filing purposes. The main difference is what programs and benefits you can access with each one.

Where to Find Your Tax ID

If you already have a tax ID, you can find it in several places. Your Social Security card displays your SSN in the center. A previous tax return — federal or state — shows your tax ID at the top. A W-2 form from any job lists your SSN in box (a). A 1099 form (for self-employment or contract work) also displays your tax ID. Bank statements, mortgage documents, and insurance policies often include your tax ID as well.

If you cannot locate your number, you can call the Social Security Administration at 1-800-772-1213 to request a replacement Social Security card. You will need to provide proof of identity, citizenship or immigration status, and age. The replacement card arrives by mail in one to two weeks. If you have an ITIN and need to confirm it, you can contact the IRS at 1-800-829-1040.

Getting a Tax ID for the First Time

If you have never had a tax ID, the process depends on your immigration status. U.S. citizens and permanent residents request an SSN from the Social Security Administration. You can apply in person at any Social Security office or by mail. You will need a birth certificate or passport, proof of age, and proof of identity. Processing takes one to two weeks in person or four to six weeks by mail.

Nonresident aliens and other noncitizens request an ITIN from the IRS using Form W-7. You can file the form by mail or in person at an IRS office, a Taxpayer Assistance Center, or an authorized acceptance agent (often a tax preparation service). You must include original documents or certified copies proving your identity and foreign status. The IRS processes Form W-7 in four to six weeks.

If you are working and need a tax ID urgently, tell your employer you have applied and provide them with a receipt or confirmation number. Most employers will accept this temporarily while you wait for your official number to arrive.

Tax ID and Your Employer

When you start a job, your employer will ask you to complete a Form W-4 (Employee's Withholding Certificate). This form asks for your tax ID so the employer can report your wages to the IRS. If you do not provide a tax ID, your employer cannot process your payroll correctly, and you may face delays in receiving your first paycheck.

At the end of the year, your employer files a W-2 form with the IRS that lists your total wages, taxes withheld, and tax ID. The IRS matches this W-2 to your tax return using your tax ID. If your tax ID on the W-2 does not match the one on your return, the IRS will flag the discrepancy and may delay processing your return or send you a notice.

If you change your name (for example, through marriage or legal change), you must notify the Social Security Administration and update your tax ID records with the IRS. This prevents mismatches between your W-2 and your tax return.

Tax ID and Self-Employment

If you are self-employed or run a business, you may need an Employer Identification Number (EIN) in addition to your personal tax ID. An EIN is a nine-digit number the IRS issues to businesses, partnerships, and certain sole proprietors. You use your personal tax ID (SSN or ITIN) to file your personal tax return and an EIN to file business taxes and hire employees.

You request an EIN from the IRS using Form SS-4. You can file online at the IRS website, by phone, by fax, or by mail. Online filing is instant; other methods take one to two weeks. You do not pay a fee for an EIN. If you are a sole proprietor with no employees, you may not need an EIN — you can use your SSN or ITIN instead — but many sole proprietors get one anyway to keep their personal and business finances separate.

Protecting Your Tax ID

Your tax ID is sensitive information. Treat it like you would a password or PIN. Do not share it with people you do not trust, and do not post it on social media or unsecured websites. Scammers can use a stolen tax ID to file a false tax return in your name and claim a refund, or to open accounts or take out loans.

If you believe your tax ID has been stolen or misused, contact the IRS immediately at 1-800-829-1040 or visit the IRS website to report identity theft. You can also file a report with the Federal Trade Commission at IdentityTheft.gov. The IRS and FTC can help you place a fraud alert on your file and take steps to prevent further misuse.

Frequently Asked Questions

Is my tax ID the same as my driver's license number?

No. Your driver's license number is issued by your state and is used for driving and identification purposes only. Your tax ID is issued by the federal government (Social Security Administration or IRS) and is used only for tax and income reporting. They are completely separate numbers.

Can I have more than one tax ID?

No. You should have only one SSN or ITIN for your entire life. If you have been issued multiple numbers by mistake, contact the Social Security Administration or IRS to consolidate them. Having multiple tax IDs can cause serious problems with your tax records and benefits.

What if I lost my Social Security card?

You can request a replacement from the Social Security Administration in person at any Social Security office or by mail. You will need proof of identity, age, and citizenship. A replacement card costs nothing and arrives in one to two weeks. You do not need the physical card to use your SSN — you can provide the number itself to your employer or the IRS.

Do I need a tax ID if I do not work?

If you are a U.S. citizen or permanent resident, you should have an SSN even if you do not work, because you may need it for banking, loans, or other purposes. If you do not work but have income from investments, rental property, or other sources, you must have a tax ID to file a tax return and report that income to the IRS.

How long does it take to get a tax ID?

An SSN takes one to two weeks if you apply in person at a Social Security office, or four to six weeks if you apply by mail. An ITIN takes four to six weeks from the IRS. An EIN is instant if you file online, or one to two weeks if you file by other methods.

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.