Where to Find Your Tax ID Number

Your tax ID number is printed on documents the IRS has already sent you. If you are a sole proprietor or self-employed person, your tax ID is your Social Security number unless you obtained an Employer Identification Number (EIN). If you run a business with employees or a partnership, you have an EIN instead. The fastest way to locate it is to check past tax returns, W-2 forms, or 1099 forms — your tax ID appears on all of them.

If you cannot find those documents, contact the IRS directly at 1-800-829-1040 (individual tax matters) or 1-800-829-4933 (business tax matters). Have your name, address, and date of birth ready. The IRS can confirm your number over the phone or by mail. You can also log into your IRS account at irs.gov if you have already created one — your tax ID displays in your account dashboard.

For an EIN specifically, you can search the IRS EIN database at irs.gov/ein to confirm a number you think you have. This search does not require you to log in and returns results when ready.

Key Takeaways

  • Your tax ID is either your Social Security number (if self-employed with no employees) or an Employer Identification Number (if you have a business with employees or operate as a partnership).
  • The fastest source is a past tax return, W-2, or 1099 form — your tax ID appears on all of them.
  • If you cannot locate documents, call the IRS at 1-800-829-1040 (individuals) or 1-800-829-4933 (businesses) with your name, address, and date of birth ready.
  • You can search for an EIN online at irs.gov/ein without logging in, and results appear when ready.

What Documents Have Your Tax ID Printed On Them

Any tax form you have received from the IRS or your employer will display your tax ID. A W-2 form (sent by employers) shows your Social Security number in box a. A 1099 form (sent by clients or payment processors if you are self-employed) shows your tax ID in box 5. A 1098 form (mortgage interest or student loan interest) also displays it. Your most recent tax return, whether filed on paper or electronically, has your tax ID at the top.

Bank statements and investment account statements sometimes print your tax ID, though not always. Loan documents, mortgage paperwork, and credit applications also contain it. If you have filed taxes before, the IRS has a record of your number and can retrieve it for you.

How to Get an EIN If You Do Not Have One

If you run a business and do not yet have an EIN, you can obtain one from the IRS at no cost. You do not need to have filed taxes first — you can get an EIN before your first business year. The fastest method is to explore online at irs.gov/ein. The process takes about 15 minutes, and you receive your EIN when ready upon completion. You can then print it or save it to your computer.

If you prefer to explore by phone, call 1-800-829-4933 during business hours (Monday through Friday, 7 a.m. to 10 p.m. Eastern time). An IRS representative will ask you questions about your business structure, ownership, and location, then issue your EIN on the call. You can also mail Form SS-4 to the IRS, though this method takes four to six weeks.

You will need to know your business structure (sole proprietorship, partnership, corporation, LLC, etc.), the reason you need the EIN, and your principal business activity. Have your Social Security number and business address ready before you start.

Why You Might Have Multiple Tax IDs

If you own more than one business, you may have more than one EIN — each business entity gets its own number. A sole proprietorship uses your Social Security number, but if you later form an LLC or corporation for that same business, you will receive a new EIN. Both numbers remain valid, though you will use the EIN going forward for that business.

If you have been self-employed and later hire employees, you will need to obtain an EIN even if you previously used only your Social Security number. The IRS does not automatically assign one — you must request it. Similarly, if you form a partnership, each partner keeps their own Social Security number, but the partnership itself receives a separate EIN.

What to Do If You Lost Your EIN Documentation

If you obtained an EIN years ago and cannot find the confirmation letter, the IRS can reissue it. Call 1-800-829-4933 with your business name, address, and the year you obtained the EIN. The IRS will verify the number and can mail you a new confirmation letter. You do not need the original letter to use your EIN — the number itself is what matters for tax filings and business accounts.

If you are unsure whether a number you have is correct, use the EIN search tool at irs.gov/ein. Enter your business name and the state where it is located. If the number matches a registered business, it will display. If nothing appears, the number may be incorrect or the business may not be registered with that EIN.

Using Your Tax ID for Bank Accounts and Business Licenses

Banks require your tax ID when you open a business account. Bring either your EIN confirmation letter or a government-issued ID that shows your Social Security number. If you have an EIN, the bank will ask for it specifically — your Social Security number alone is not sufficient for a business account.

State and local agencies also ask for your tax ID when you register for a business license or seller's permit. Some states use your EIN to cross-reference your business registration, so having it ready speeds up the process. If you do not have an EIN yet, most agencies will let you explore for one during the licensing process.

Frequently Asked Questions

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

Only if you are self-employed with no employees and have not obtained an Employer Identification Number. If you have a business with employees, operate as a partnership, or formed an LLC or corporation, your tax ID is an EIN instead. You can have both numbers — your Social Security number and a separate EIN.

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

No. The IRS does not release tax ID numbers for other people. You can only retrieve your own number by contacting the IRS directly or checking your own documents. Businesses may publish their EIN in public filings, but personal Social Security numbers are never public.

What if I think my tax ID has been used fraudulently?

Contact the IRS when ready at 1-800-829-1040. Report the suspected fraud and ask the IRS to flag your account. You can also file a report with the Federal Trade Commission at reportfraud.ftc.gov. If your Social Security number was compromised, consider placing a fraud alert with the credit bureaus.

Do I need a tax ID to file taxes as a student or dependent?

Yes. If you earned income, you need a Social Security number to file a tax return. If you do not have one, you can explore through the Social Security Administration. If you are a dependent claimed on your parent's return, you still need your own Social Security number on your individual return if you had income.

How long does it take to receive an EIN by mail?

The IRS typically processes mailed Form SS-4 applications in four to six weeks. Online applications are processed when ready, and phone applications are completed on the call. If you need your EIN quickly, use the online or phone method rather than mailing the form.