Your tax ID is printed on documents the IRS has already sent you

Your tax ID number appears on several documents you likely already have at home. For most people, it is your Social Security number. If you are self-employed or run a business, you may have an Employer Identification Number (EIN) instead, which the IRS issued separately. The fastest way to find it is to check the documents listed below — you do not need to contact the IRS unless none of these sources have it.

You do not need to request a new number or file any paperwork to retrieve one you already have. The IRS keeps records of every tax ID it has issued, so a lost number can be found by calling or checking your online account.

Key Takeaways

  • Your Social Security number is your tax ID if you work as an employee; check your Social Security card, W-2 forms, or bank statements to find it.
  • An EIN is a nine-digit number the IRS issues to businesses and self-employed people; it appears on your EIN assignment letter and any business tax returns you have filed.
  • If you cannot find your number in any document, you can call the IRS directly at 1-800-829-1040 or check your online IRS account through IRS.gov.
  • The IRS keeps records of every tax ID it has issued, so you can retrieve a lost number without filing a new request.

Where your Social Security number appears

If you are an employee, your Social Security number is your tax ID. You can find it on your original Social Security card, which is the most straightforward source. If you no longer have the card, check any of these documents: your most recent W-2 form (the box labeled "a" shows your SSN), your 1099 form if you received one, or any tax return you filed in the past three years.

Bank statements and investment account statements also display your Social Security number, usually in a section labeled "Tax ID" or near account information. Employer pay stubs show it as well. If you have filed taxes before, your prior tax return will have it printed at the top. Any of these documents will give you the number you need.

Where your EIN appears if you are self-employed or own a business

An EIN is a nine-digit identifier the IRS assigns to businesses, partnerships, and self-employed people who hire employees. It looks like this: 12-3456789. The IRS sent you an EIN Assignment Letter (Form SS-4) when you first received your number — this is the official document to keep. If you still have it, your EIN is printed clearly on the first page.

If you have filed a business tax return, your EIN appears on that return as well. Self-employed people file Schedule C (Form 1040-C) as part of their individual return; the EIN goes in a specific box on that form. If you have a business bank account, the EIN is on statements and checks. Payroll records, business licenses, and loan documents from your bank also list it.

How to retrieve a lost tax ID from the IRS

If you cannot find your number in any document, you can contact the IRS directly. Call 1-800-829-1040 during business hours (Monday through Friday, 7 a.m. to 7 p.m. your local time). Have your name, date of birth, and address ready. The IRS representative will confirm your identity and provide your number over the phone.

You can also create or log into your account on IRS.gov. Once you are signed in, your tax ID will appear in your account dashboard. This method works if you have already filed a tax return with the IRS, because they use that information to verify your identity online. Both routes take a few minutes and require no paperwork.

The difference between a Social Security number and an EIN

A Social Security number is issued by the Social Security Administration to every U.S. citizen, permanent resident, and work-authorized person. It is nine digits and is your tax ID if you work as an employee. You receive it once in your lifetime and keep it even if you change jobs.

An EIN is issued by the IRS only to businesses, self-employed people with employees, partnerships, corporations, and certain other entities. You request an EIN through the IRS, usually when you start a business. You can have multiple EINs if you own multiple businesses, and you can request a new one if needed. Some self-employed people have both a Social Security number (for personal taxes) and an EIN (for business taxes).

What to do if you think you have the wrong number

If you believe the number you found is incorrect, or if you have been assigned multiple numbers, contact the IRS at 1-800-829-1040. Bring any documents that show different numbers — the IRS can review your file and clarify which number is correct. This sometimes happens when someone files taxes under different names or when records are duplicated in the system.

Do not request a new tax ID unless the IRS tells you to. Changing your number creates complications with the IRS, the Social Security Administration, your employer, and your bank. The IRS will help you confirm which number belongs to you before you make any changes.

Frequently Asked Questions

Is my tax ID the same as my Social Security number?

For most people, yes. If you work as an employee, your Social Security number is your tax ID. If you are self-employed or own a business, you may have an EIN instead, or you may use both depending on how your business is structured. Check your most recent tax return to see which number the IRS has on file for you.

Can I look up someone else's tax ID?

No. Tax ID numbers are private information protected by federal law. You cannot retrieve another person's number from the IRS, even if you have a business reason. If you need a business partner's or employee's tax ID, you must ask them directly or request it through your payroll or accounting system.

What if I lost my EIN assignment letter?

You do not need the original letter to use your EIN. The number itself is what matters. If you need a copy of the letter for your records, call the IRS at 1-800-829-1040 and request a transcript or copy of your EIN assignment. You can also retrieve it through your IRS online account if you have one set up.

Do I need to report a lost or stolen tax ID to anyone?

If you believe your Social Security number or EIN has been stolen or misused, contact the IRS at 1-800-829-1040 and file a report. You should also place a fraud alert with the three major credit bureaus (Equifax, Experian, and TransUnion) and monitor your credit report for unauthorized accounts or activity.