Your Tax ID is printed on documents you already have

Your Tax ID number — also called an EIN, ITIN, or SSN depending on your situation — appears on mail from the IRS, your Social Security card, and tax documents you've filed before. You do not need to request it or contact anyone to "find" it; you need to locate the document where it's already written.

The specific document depends on what kind of tax ID you hold. If you are a sole proprietor or individual filer, your number is your Social Security number. If you run a business entity, you have an Employer Identification Number. If you are not a U.S. citizen but file taxes, you have an Individual Taxpayer Identification Number. Each one lives in a different place, and knowing which type you need is the first step.

Key Takeaways

  • Your Social Security number is your tax ID if you file as an individual; it's on your Social Security card and any tax return you've filed.
  • An Employer Identification Number (EIN) is issued to businesses and appears on IRS correspondence, business tax returns, and the EIN assignment letter you received when you applied.
  • An Individual Taxpayer Identification Number (ITIN) is for non-citizens who file taxes and appears on IRS notices and your ITIN assignment letter.
  • If you've filed a tax return in the past five years, your tax ID is on that return — check your records or request a transcript from the IRS.
  • The IRS can confirm your tax ID by phone or mail if you have lost all documents, but the process takes several weeks.

Social Security Number as your tax ID

If you file taxes as an individual — whether you work as an employee, self-employed, or both — your Social Security number is your tax ID. This is the nine-digit number on your Social Security card, formatted as XXX-XX-XXXX.

Check these places first: your Social Security card itself, any tax return you filed (Form 1040 or similar), a W-2 from an employer, a 1099 form from a client or bank, or a letter from the IRS about your account. If you have filed taxes online through a tax software company, log into that account and your number will appear on the return you prepared.

If you cannot locate your card and have no tax documents, you can request a replacement Social Security card from your local Social Security office. Bring a government-issued ID and proof of citizenship or legal residency. The replacement card arrives by mail in one to two weeks.

Employer Identification Number for businesses

An Employer Identification Number (EIN) is a nine-digit number assigned to a business entity — a corporation, partnership, LLC, nonprofit, or sole proprietor who hires employees. It is formatted as XX-XXXXXXX and is separate from your personal Social Security number.

Your EIN appears on the IRS assignment letter you received when you first applied for it. This letter, titled "Notice of Action on Your Application for an Employer Identification Number," was mailed to you by the IRS and should be in your business records. Check files labeled "IRS correspondence," "business formation," or "tax documents."

If you cannot find the assignment letter, check your business tax returns (Form 1120, 1120-S, 1065, or 990), business bank statements, or payroll records — your EIN appears on all of these. You can also call the IRS Business and Specialty Tax Line at 800-829-4933 with your business name and address, and they will confirm your EIN over the phone.

Individual Taxpayer Identification Number for non-citizens

An Individual Taxpayer Identification Number (ITIN) is a nine-digit number issued by the IRS to non-citizens who file U.S. tax returns but do not have a Social Security number. It is formatted as 9XX-XX-XXXX and functions as your tax ID for filing purposes.

Your ITIN appears on the IRS assignment letter you received when you applied, titled "Notice of Action on Your Application for an Individual Taxpayer Identification Number." This letter was mailed to you and should be kept with your tax documents. It also appears on any tax return you have filed since receiving it.

If you have lost the assignment letter and your tax documents, you can request a transcript of your account from the IRS, which will show your ITIN. Use Form 4506-C or call the IRS at 800-829-1040 and request an account transcript. Processing takes 5 to 10 business days by mail or 24 hours if you request it online through your IRS account.

Tax returns and IRS transcripts as backup sources

If you have filed a federal tax return at any point in the past five years, your tax ID is on that return. Locate the return itself — check your computer files if you filed electronically, your tax preparer's records, or paper copies in your files. The tax ID appears in the top-right corner of the first page.

If you cannot find your copy of the return, you can request a transcript from the IRS. An account transcript shows your filing history and tax ID. Use Form 4506-C (Request for Transcript of Tax Return), available on the IRS website, or call 800-829-1040. You can also create an account on IRS.gov and download transcripts immediately at no cost.

Processing by mail takes 5 to 10 business days. Online retrieval through your IRS account is instant. You will need to verify your identity — the IRS will ask for your name, address, date of birth, and filing status from a recent return.

Contacting the IRS directly

If you have no documents and cannot locate your tax ID through any of the above methods, you can contact the IRS directly. Call 800-829-1040 (individual taxpayers) or 800-829-4933 (business taxpayers). Have your name, address, date of birth, and any business information ready.

The IRS can confirm your tax ID over the phone if you pass identity verification. They will ask security questions based on your tax history or credit file. If you cannot verify your identity by phone, the IRS will mail you a letter with your tax ID, which takes 2 to 4 weeks.

You can also visit a local IRS office in person. Use the IRS office locator on IRS.gov to find the nearest location. Bring a government-issued photo ID and any tax documents you have. Walk-in service is available, though wait times vary by location.

Frequently Asked Questions

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

Only if you file taxes as an individual. Your Social Security number serves as your tax ID for personal tax returns. If you own a business entity, you have a separate Employer Identification Number. If you are a non-citizen filing taxes, you have an Individual Taxpayer Identification Number instead of a Social Security number.

What if I've never filed taxes before?

If you have never filed a tax return, you still have a tax ID — it is your Social Security number. You do not need to create or request one. If you are a non-citizen without a Social Security number, you would apply for an ITIN through Form W-7 if you plan to file taxes. If you own a business, you would apply for an EIN through Form SS-4.

Can I look up someone else's tax ID?

No. Tax ID numbers are confidential. The IRS will only confirm a tax ID to the person it belongs to or an authorized representative with power of attorney. You cannot retrieve another person's tax ID through the IRS, even if you are a family member or business partner.

How long does it take to get a replacement tax ID if I've lost mine?

If your tax ID is a Social Security number, you can get a replacement card in one to two weeks by visiting your local Social Security office. If it is an EIN or ITIN and you have lost all documentation, requesting an IRS transcript takes 5 to 10 business days by mail or is instant online through your IRS account.

What documents do I need to bring to prove my tax ID?

If you are requesting a replacement Social Security card, bring a government-issued photo ID and proof of citizenship or legal residency. If you are requesting an IRS transcript or confirmation of an EIN or ITIN, you need to verify your identity through the IRS — this is done by phone, mail, or online through your IRS account, not in person at most locations.