Where to find your tax ID number depends on what type of ID you need

Your tax ID number is a nine-digit identifier the IRS uses to track your tax account. If you are a sole proprietor or individual, this is your Social Security number. If you own a business, it is an Employer Identification Number (EIN). If you are a nonresident alien or someone without a Social Security number, it may be an Individual Taxpayer Identification Number (ITIN). The fastest way to find it is to check documents you already have — your Social Security card, past tax returns, or business formation papers.

If you cannot locate your tax ID in your existing documents, the method to retrieve it depends on which type you need. For a Social Security number, you can order a tax transcript from the IRS. For an EIN, you can search the IRS database using your business information. For an ITIN, you can check past returns or request a new one by mail. In all cases, the IRS does not issue tax ID numbers by phone or email for new requests — though you can call to verify a number you already have.

Key Takeaways

  • Your Social Security number is your tax ID if you file as an individual; check your Social Security card, W-2, or past tax return to find it.
  • An EIN is a nine-digit business tax ID you can look up on the IRS website using your business name and formation date, or request a new one if you cannot find the original.
  • An ITIN is issued to nonresident aliens and others ineligible for a Social Security number; you can find it on past tax returns or request one by mail using Form W-7.
  • The IRS does not issue tax ID numbers by phone or email, and you cannot look up someone else's tax ID without their permission.

Finding your Social Security number as your individual tax ID

If you file taxes as an individual, your Social Security number is your tax ID. You can find it on your Social Security card itself — the nine digits printed on the front. If you do not have your card, check any of these documents: a W-2 form from an employer, a 1099 form from a contractor or financial institution, a past year's tax return, a bank or investment account statement, or a mortgage or loan document.

If you have filed taxes before, the easiest source is often your most recent tax return. The IRS keeps records of returns filed under your Social Security number, so if you can locate any return you submitted, your number appears on it. You can also request a transcript of your tax account from the IRS, which displays your Social Security number and filing history. To order a transcript, visit IRS.gov, call 1-800-908-9946, or mail Form 4506-C to the IRS address listed on the form.

Looking up an EIN for your business

An Employer Identification Number (EIN) is a nine-digit tax ID assigned to businesses, partnerships, corporations, nonprofits, and trusts. If you formed a business and received an EIN, the IRS sent it to you by mail in a letter called a Form SS-4 confirmation. Check your business records, email, or filing cabinet for this letter — it contains your EIN and the date it was issued.

If you cannot find the original letter, you can look up your EIN on the IRS website using the EIN Lookup Tool at IRS.gov. You will need your business legal name exactly as it appears on your Form SS-4, your business address, and the approximate date you applied for the EIN. The tool searches the IRS database and displays your number if the information matches. If the lookup tool does not find your EIN, it may mean the process was never processed, or the information you entered does not match IRS records exactly. In that case, you can explore for a new EIN by filing Form SS-4 online at IRS.gov, by phone at 1-800-829-4933, or by mail.

Requesting an ITIN if you do not have a Social Security number

An Individual Taxpayer Identification Number (ITIN) is a tax ID issued by the IRS to nonresident aliens, dependents without a Social Security number, and other individuals ineligible for a Social Security number who need to file taxes or report income. An ITIN is nine digits and looks like a Social Security number but begins with the number 9.

If you have filed taxes before and received an ITIN, check your past tax returns — the number appears on Form 1040 or whichever return you filed. You can also order a tax transcript from the IRS, which will show your ITIN and filing history. To request an ITIN for the first time, you must file Form W-7 (process for IRS Individual Taxpayer Identification Number) by mail along with documents proving your identity and residency status. The IRS does not issue ITINs online or by phone. Processing typically takes four to six weeks. You can find the mailing address and required documents on the Form W-7 instructions at IRS.gov.

What to do if you have lost or forgotten your tax ID number

If you cannot find your tax ID number in any of your documents and the lookup tools do not work, you can contact the IRS directly. Call the IRS at 1-800-829-1040 (for individual tax matters) or 1-800-829-4933 (for business and EIN matters). Have your name, date of birth, and address ready. The IRS representative will verify your identity and provide your tax ID number over the phone.

If you are looking for an ITIN and cannot locate it, you will need to file Form W-7 again. The IRS will issue a new ITIN if you meet the requirements. You can check the status of a pending ITIN process by calling 1-800-829-1040 and providing your Form W-7 receipt number.

Why you might need to look up your tax ID number

You need your tax ID number to file a tax return, open a business bank account, hire employees, explore for a business loan, report income to the IRS, or claim certain tax deductions and credits. Employers and financial institutions also ask for your tax ID number to report income they have paid you — this is why it appears on W-2s, 1099s, and bank interest statements.

If you are helping someone else locate their tax ID number, remember that the IRS does not share tax ID numbers with third parties without written consent. If you need someone else's tax ID for business or legal purposes, you must ask them directly or obtain a power of attorney document authorizing you to act on their behalf.

Frequently Asked Questions

Can I look up someone else's tax ID number?

No. The IRS does not release tax ID numbers to anyone except the person who owns the number or someone with written power of attorney. If you need a business partner's EIN or an employee's Social Security number for payroll, you must ask them directly.

What if the IRS EIN lookup tool says my business does not exist?

This usually means your Form SS-4 process was never processed, or the information you entered does not match IRS records. Double-check the business legal name and address. If it still does not appear, file a new Form SS-4 online or by phone to receive a new EIN.

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

Yes, for individuals. Your Social Security number is your tax ID. Businesses use an EIN instead. Nonresident aliens and others ineligible for a Social Security number use an ITIN as their tax ID.

How long does it take to receive an ITIN?

The IRS typically processes Form W-7 applications within four to six weeks. You can check the status of your process by calling 1-800-829-1040 with your receipt number.

Can I get a tax ID number online?

You can explore for an EIN online at IRS.gov and receive it when ready. You cannot explore for a Social Security number or ITIN online — Social Security numbers are issued by the Social Security Administration, and ITINs require Form W-7 submitted by mail with identity documents.