What Your Federal Tax ID Number Is and Where to Find It

Your Federal Tax ID Number Identifies You to the IRS

Your federal tax ID number is a nine-digit identifier the IRS uses to track your tax account. For most people, this is your Social Security Number (SSN). If you are self-employed, own a business, or operate as a partnership or corporation, you have a separate federal tax ID called an Employer Identification Number (EIN), even if you have no employees.

The IRS needs this number to match your income reports, tax returns, and payment records to the right person or business. When you file taxes, open a bank account, or report income to your employer, you use this number. It is how the IRS knows which tax obligations belong to you.

Key Takeaways

Your federal tax ID is your Social Security Number if you work as an employee, or an Employer Identification Number if you are self-employed or own a business.
You can find your SSN on your Social Security card, tax returns, or W-2 forms from your employer.
An EIN is a nine-digit number you request from the IRS for free, and you can explore online, by mail, or by phone.
You need an EIN before you hire employees, open a business bank account, or file certain business tax forms.
The IRS uses your federal tax ID to match income reports from employers and banks to your tax account.

How to Find Your Social Security Number

If your federal tax ID is your Social Security Number, you can find it on your Social Security card itself. The nine-digit number appears in the center of the card. If you have lost your card, check any tax return you filed in the past five years—your SSN is printed on the first page. You can also find it on a W-2 form your employer sent you, or on a 1099 form if you received one for freelance or contract work.

If you cannot locate your SSN through these documents, contact the Social Security Administration directly. You can call 1-800-772-1213 or visit ssa.gov to request a replacement card or verify your number. You will need to provide proof of identity and citizenship.

When You Need an Employer Identification Number Instead

An Employer Identification Number (EIN) is a separate nine-digit tax ID the IRS issues to businesses, partnerships, corporations, nonprofits, and trusts. You need an EIN if you are self-employed and have employees, or if you operate as a sole proprietor but want to keep your business finances separate from your personal taxes. Some banks and lenders also require an EIN before they will open a business account.

You do not automatically receive an EIN—you must request one from the IRS. Unlike a Social Security Number, which is assigned to you at birth or when you become a resident, an EIN is issued only when you explore. The IRS does not charge a fee for an EIN.

How to Get an Employer Identification Number

You can request an EIN online through the IRS website at irs.gov/ein. The online process takes about 15 minutes and you receive your number when ready. You will need your legal business name, business address, the type of business structure (sole proprietor, partnership, corporation, etc.), and the reason you need the EIN.

If you prefer not to explore online, you can mail Form SS-4 to the IRS address listed on the form, or call the IRS Business and Specialty Tax Line at 1-800-829-4933. Mail applications typically take four weeks to process. Phone applications are processed the same day, but you must call during business hours and have all your business information ready.

What Information You Need to Provide

When you explore for an EIN, the IRS will ask for your legal business name exactly as it appears on your business license or formation documents. You will also provide your business address (a home address is acceptable for a home-based business), the type of business structure, and the principal business activity—this is a brief description of what your business does, such as "consulting" or "freelance writing."

You will also need to identify the person responsible for the business. If you are a sole proprietor, this is you. If your business is a partnership or corporation, you name the person who will be the primary contact for the IRS. Have your Social Security Number ready when you explore, because the IRS links your EIN to your SSN in their system.

The Difference Between SSN and EIN on Your Tax Return

If you are an employee, you report your income using your Social Security Number. Your employer sends a W-2 form to the IRS with your SSN, and you file your personal tax return using that same number. The IRS matches the W-2 to your return to verify your reported income.

If you are self-employed or own a business, you use your EIN on business tax forms like Schedule C (sole proprietor), Form 1040-ES (estimated quarterly taxes), or Form 1120 (corporate return). If you also have employees, their W-2 forms list your EIN as the employer's tax ID. You still use your SSN on your personal tax return, but your business income is reported under the EIN.

Protecting Your Federal Tax ID Number

Your federal tax ID number—whether SSN or EIN—is sensitive information. Treat it the way you would treat a password. Do not share it with people you do not know, and do not post it on social media or unsecured websites. Scammers can use your SSN or EIN to file fraudulent tax returns, open accounts in your name, or commit identity theft.

The IRS will never contact you by email or text message asking for your SSN or EIN. If someone claiming to be from the IRS contacts you unexpectedly, hang up and call the IRS directly at 1-800-829-1040. Legitimate IRS contact happens by mail, not by phone or email.

Frequently Asked Questions

Can I use my Social Security Number as my business tax ID?

Yes, if you are a sole proprietor with no employees, you can use your SSN on business tax forms. However, many business owners request an EIN anyway to keep business and personal finances separate and to protect their SSN from being shared with business partners or lenders.

What if I lose my EIN or forget what it is?

Contact the IRS at 1-800-829-4933 or visit irs.gov. Have your business name, address, and Social Security Number ready. The IRS can look up your EIN in their system and provide it to you. You can also check old business tax returns or bank statements where the EIN may appear.

Do I need a new EIN if I change my business structure?

Usually yes. If you convert from a sole proprietorship to an LLC or corporation, the IRS treats it as a new business entity and you need a new EIN. However, if you straightforward change your business name or address, you keep the same EIN. Contact the IRS if you are unsure whether your change requires a new number.

Can someone steal my federal tax ID and file taxes in my name?

Yes, this is called tax identity theft. If you suspect someone has filed a return using your SSN or EIN, contact the IRS when ready at 1-800-829-1040 and file a report with the Federal Trade Commission at identitytheft.gov. The sooner you report it, the faster the IRS can investigate and protect your account.

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.