Your Tax ID Number Is Already Assigned — You Just Need to Locate It

Your tax ID number is a nine-digit identifier the IRS assigns to you. If you are a U.S. citizen or permanent resident, this is your Social Security Number (SSN). If you are not a citizen but file taxes, you have an Individual Taxpayer Identification Number (ITIN). If you own a business or operate as a sole proprietor, you may have an Employer Identification Number (EIN). The number already exists in IRS records — you are not creating one, you are finding the one that belongs to you.

The fastest way to find it is to check documents you already have at home. If that does not work, you can request it from the IRS by mail or phone. The process takes a few days to a few weeks depending on which method you use.

Key Takeaways

  • Your Social Security Number is your tax ID if you are a U.S. citizen or permanent resident; it appears on your Social Security card, tax returns, and W-2 forms.
  • An ITIN is a tax ID for non-citizens who file taxes; it is a nine-digit number starting with 9 and appears on your ITIN letter from the IRS.
  • An EIN is a tax ID for businesses and is different from your personal tax ID; you can look it up on the IRS website if you registered one.
  • If you cannot find your number in your documents, you can call the IRS at 1-800-829-1040 or request a transcript by mail, which takes one to two weeks.

Check Your Documents First

Start by looking for documents that already show your tax ID. Your Social Security card displays your nine-digit SSN on the front. If you do not have the card itself, check any of these:

  • A past tax return (Form 1040, 1040-SR, or 1040-NR)
  • A W-2 form from an employer
  • A 1099 form (for self-employment or contract income)
  • A bank or investment account statement
  • A mortgage or loan document
  • Your state ID or driver's license (some states print SSN on the back)

If you have an ITIN instead of an SSN, look for your IRS Letter of Acceptance — this is the official document the IRS mailed you when your ITIN was created. It shows your nine-digit ITIN and the date it was assigned. Keep this letter safe; you will need it to file taxes and for some financial transactions.

If you own a business and need your EIN, check any business tax returns you have filed, your business bank account statements, or loan documents. You can also look it up on the IRS website using the EIN Lookup Tool at irs.gov if you registered the business with the IRS.

Call the IRS to Retrieve Your Number

If you cannot find your tax ID in your documents, you can call the IRS directly. The main phone line is 1-800-829-1040. Have your name, date of birth, and mailing address ready. The IRS will verify your identity and read your number to you over the phone.

Wait times are longest during tax season (January through April). If you call outside those months, you will usually reach someone within 15 to 30 minutes. The IRS does not take appointments, so you call and wait in a queue.

If you are deaf or hard of hearing, use the TTY line at 1-800-829-4059. If you speak a language other than English, interpreters are available at the main number.

Request a Transcript by Mail

If you prefer not to call, you can request an IRS Account Transcript by mail. This document shows your tax ID and your filing history. You will need to fill out Form 4506-C (Request for Transcript of Tax Return) or Form 4506-C-Z (for a shorter version). Both are free.

Mail the form to the IRS address listed on the form itself — it varies by state. Processing takes 5 to 10 business days. You can also order a transcript online at irs.gov/transcripts if you create an IRS online account, and it will arrive by email within 24 hours.

You do not need to have filed a tax return to get a transcript. Even if you have never filed, the IRS has your SSN or ITIN on record if you have a Social Security card or an ITIN letter.

What to Do If You Never Received an ITIN Letter

If you applied for an ITIN but never received the acceptance letter, contact the IRS at 1-800-829-1040 and ask for your ITIN status. Have your passport or other identification ready. The IRS can tell you whether your ITIN was approved and what the number is.

If your ITIN application was denied, the IRS will explain why. Common reasons include incomplete documentation, missing signatures, or an expired passport. You can reapply with corrected documents.

If you lost your ITIN letter, you can request a replacement by calling the IRS or by filing Form W-7 again with a note that you are requesting a duplicate letter. The IRS will mail you a new one.

Understanding Which Tax ID You Actually Need

You have only one tax ID for personal income. If you are a U.S. citizen or permanent resident, that is your SSN. You do not get an ITIN if you have an SSN. If you are not a citizen and you work or have income in the U.S., you get an ITIN instead of an SSN.

An EIN is separate and is only for business purposes. If you are self-employed as a sole proprietor, you can use your SSN or ITIN to file business taxes — you do not need an EIN unless you hire employees or form a partnership or corporation. If you do have an EIN, it does not replace your personal tax ID; you use both on different forms.

If you are unsure which one you need, the IRS website has a tool to help you determine this. You can also ask a tax preparer or call the IRS at the number above.

Frequently Asked Questions

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

No. Tax ID numbers are private information. The IRS will only release your own number to you, or to someone you authorize in writing. You cannot look up another person's SSN, ITIN, or EIN without their permission and a legal reason to have it.

What if I lost my Social Security card but know my number?

You do not need the card itself to file taxes or use your SSN. Your number is what matters. If you want a replacement card, you can order one from the Social Security Administration at ssa.gov or visit a local Social Security office. There is no charge for a replacement card.

How long does it take to get an ITIN if I do not have one yet?

ITIN processing takes 6 to 8 weeks if you mail Form W-7 to the IRS. If you file a tax return that includes Form W-7, the IRS processes both together and may issue your ITIN within the same timeframe. You cannot use an ITIN until the IRS approves it and mails you the acceptance letter.

Is my tax ID the same as my employer identification number?

No. Your tax ID is your personal identifier (SSN or ITIN). An EIN is a business identifier. If you own a business, you have both. Your employer uses your SSN or ITIN to report your wages on a W-2; they use an EIN to identify themselves to the IRS.

What should I do if I think someone is using my tax ID fraudulently?

Contact the IRS immediately at 1-800-829-1040 and report identity theft. You can also file a report with the Federal Trade Commission at identitytheft.gov. The IRS has a process to help victims of tax-related identity theft, and you may need to file Form 14039 (Identity Theft Affidavit) with your tax return.