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 a number assigned by the Internal Revenue Service (IRS) to identify you when you file taxes, open a business, or work in the United States. It looks like this: XX-XXXXXXX (nine digits with a hyphen). The IRS uses it to track your income, tax payments, and filing history.

Most people have one of two types: a Social Security Number (SSN) if you work as an individual, or an Employer Identification Number (EIN) if you own a business or operate as a sole proprietor. Some people have both. The number you use depends on how you earn income and what the IRS requires for your situation.

You will need your Tax ID to file a tax return, receive a refund, open a bank account, explore for credit, or report income from self-employment. Your employer also uses it to report your wages on your W-2 form.

Key Takeaways

A Tax ID is a nine-digit number the IRS assigns to track your tax information and income.
A Social Security Number (SSN) serves as a Tax ID for most employees and individuals.
An Employer Identification Number (EIN) is a Tax ID for businesses, partnerships, and self-employed people who hire employees.
You need your Tax ID to file taxes, receive refunds, open bank accounts, and report income to the IRS.
You can find your Tax ID on tax documents, W-2 forms, or by contacting the IRS directly.

Social Security Number as a Tax ID

If you work as an employee or are a U.S. citizen or permanent resident, your Social Security Number (SSN) is your Tax ID. The Social Security Administration issues SSNs, and the IRS uses them to file your personal tax return and track your income history.

Your SSN appears on your Social Security card, your tax returns, and any W-2 forms your employer sends you. If you were born in the United States or have permanent resident status, you received an SSN automatically or applied for one through the Social Security Administration.

You use your SSN on Form 1040 (the main individual tax return form) and when you report income from jobs, investments, or other sources. Banks, employers, and credit card companies also ask for your SSN to verify your identity and report financial activity to the IRS.

Employer Identification Number for businesses

An Employer Identification Number (EIN) is a Tax ID for businesses, partnerships, and self-employed people. The IRS issues EINs to identify business entities for tax purposes. If you own a business or operate as a sole proprietor with employees, you need an EIN.

An EIN is nine digits in the format XX-XXXXXXX, the same as an SSN, but it identifies your business rather than you personally. You use an EIN to file business tax returns, hire employees, open a business bank account, and report business income to the IRS.

Some sole proprietors without employees can use their SSN instead of an EIN, but many choose to get an EIN to keep their personal and business finances separate. You can request an EIN from the IRS for free through their website, by mail, or by phone.

Where to find your Tax ID

Your Tax ID appears on several documents you likely already have. If you have an SSN, it is printed on your Social Security card. It also appears on any tax return you have filed, on your W-2 form from your employer, and on bank statements or investment account statements.

If you have an EIN, you received a letter from the IRS when the number was issued. That letter (Form SS-4) contains your EIN and is the official record. You can also find your EIN on business tax returns you have filed or on business bank account statements.

If you cannot locate your Tax ID, you can contact the IRS directly. Call the IRS at 1-800-829-1040 (for personal SSN questions) or 1-800-829-4933 (for business EIN questions). Have your identification ready, and the IRS can confirm your number over the phone.

When you need to provide your Tax ID

You will need to provide your Tax ID in several common situations. When you file a tax return with the IRS, your Tax ID goes on the form. When you start a new job, your employer asks for your SSN to report your wages on a W-2. When you open a bank account or explore for credit, the bank or lender asks for your Tax ID to verify your identity and check your credit history.

If you receive income from investments, rental property, or self-employment, you report that income using your Tax ID. If you hire a contractor or employee, you use their Tax ID to report what you paid them. Insurance companies, mortgage lenders, and government agencies also ask for your Tax ID when you interact with them.

Protecting your Tax ID

Your Tax ID is sensitive information, similar to a password. Treat it carefully and share it only when necessary. Do not post it on social media, email it to unknown recipients, or leave documents with your Tax ID visible in public places.

The IRS will never ask for your Tax ID by email or unsolicited phone call. If someone contacts you claiming to be from the IRS and demands your Tax ID, it is likely a scam. Hang up and call the IRS directly using the number on their official website or on a tax document you trust.

If you believe your Tax ID has been stolen or misused, contact the IRS when ready and consider placing a fraud alert with the credit bureaus. You can also file a report with the Federal Trade Commission at IdentityTheft.gov.

Frequently Asked Questions

Is my Social Security Number the same as my Tax ID?

Yes, for most people. Your Social Security Number is your Tax ID if you work as an employee or are a U.S. citizen or permanent resident. The IRS uses your SSN to identify you on tax returns and track your income. If you own a business, you may also have an EIN, which is a separate Tax ID for that business.

Do I need both an SSN and an EIN?

Not always. If you are self-employed without employees, you can use your SSN as your Tax ID. However, many self-employed people get an EIN to keep personal and business finances separate. If you have employees or operate as a partnership or corporation, you must have an EIN.

How do I get an EIN if I do not have one?

You can request an EIN from the IRS for free. Visit the IRS website and explore online, mail Form SS-4 to the IRS, or call 1-800-829-4933. The IRS issues EINs when ready online or within a few weeks by mail. You do not need to pay any fee.

What should I do if I lost my Tax ID?

If you lost your SSN card, you can request a replacement from the Social Security Administration. If you lost your EIN documentation, contact the IRS and they can confirm your number. Have your identification ready. You do not need to request a new number unless your Tax ID was stolen or misused.

Can someone use my Tax ID without my permission?

Yes, which is why identity theft is a serious concern. If you suspect someone is using your Tax ID fraudulently, contact the IRS, place a fraud alert with credit bureaus, and file a report at IdentityTheft.gov. The IRS can help you resolve fraudulent tax filings or accounts opened in your name.

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.