Your Tax ID Number Is Already Assigned — You Just Need To Locate It
Your tax ID number exists in multiple places depending on what type of ID you need. 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) from the IRS. If you run a business with employees or a partnership, you have an EIN. The IRS assigned your number to you — you did not create it — so finding it means checking the documents you already have or contacting the agency that issued it.
The fastest way to find your number is to look at documents you received from the IRS or your employer. If you cannot locate it that way, you can contact the IRS directly or request a transcript that displays your number. The process takes minutes if you have your documents, or a few business days if you need to request one from the IRS.
Key Takeaways
- Your Social Security number is your tax ID if you are self-employed and have never obtained an EIN from the IRS.
- An EIN is a nine-digit number formatted as XX-XXXXXXX that the IRS issues to businesses, partnerships, and certain other entities.
- Check your past tax returns, IRS letters, business bank account paperwork, and employer documents first — your number appears on all of them.
- If you cannot find your number in writing, you can call the IRS Business and Specialty Tax Line at 1-800-829-4933 or request a transcript online through your IRS account.
- The IRS keeps records of every EIN it has issued, so you can retrieve your number even if you have lost all copies of it.
Where Your Tax ID Appears in Documents You Already Have
Start by looking at any tax return you filed in the past three years. Your tax ID number appears at the top of Form 1040 (individual return) or Form 1120 (business return). If you filed electronically, check your email for the confirmation receipt from the IRS — it includes your number. If you filed on paper, look at the copy you kept or contact the tax preparer who filed it for you.
Check any letter the IRS sent you. These letters reference your tax ID in the header or body text. Common letters include notices about tax refunds, payment plans, or tax year correspondence. If you received an EIN, the IRS sent you a letter on Form SS-4 confirmation — this letter contains your nine-digit EIN and is often the clearest source.
Look at your business bank account paperwork. Banks require your tax ID to open a business account, so it appears on your account opening documents, monthly statements, and any 1099 forms the bank sends you. If you have employees, your payroll records and W-2 forms you issued to them both display your EIN.
How To Find Your Number Through IRS Records
If you cannot locate your number in documents, the IRS can retrieve it for you. Create an account on IRS.gov and log into your online account. Once logged in, you can view your tax transcript, which displays your tax ID number at the top. This method works for both Social Security numbers and EINs.
To create an IRS online account, you will need your Social Security number, date of birth, filing status from your most recent tax return, and a valid email address. The IRS verifies your identity before granting access. Once your account is set up, you can view your transcript immediately without waiting.
If you do not want to create an online account, you can call the IRS directly. For individual tax matters, call 1-800-829-1040. For business tax matters and EINs, call 1-800-829-4933. Have your Social Security number, date of birth, and the address on file with the IRS ready when you call. The IRS representative can confirm your tax ID number over the phone.
The Difference Between a Social Security Number and an EIN
A Social Security number is a nine-digit identifier issued by the Social Security Administration. If you are self-employed and do not have employees, your Social Security number is your tax ID. You use it on your individual tax return (Form 1040) and on Schedule C if you report self-employment income. The IRS does not issue Social Security numbers — you received yours from Social Security when you were born or when you immigrated.
An Employer Identification Number (EIN) is a nine-digit number issued by the IRS, formatted as XX-XXXXXXX (for example, 12-3456789). You need an EIN if you operate a business with employees, form a partnership, create a corporation or LLC, or operate certain types of entities like trusts or nonprofits. You obtain an EIN by filing Form SS-4 with the IRS. The IRS assigns the number to you immediately — you do not choose it.
Some self-employed people obtain an EIN even though they do not have employees, usually to keep their business finances separate from personal finances or to open a business bank account. If you have obtained an EIN, that becomes your business tax ID, and you use it on business tax returns instead of your Social Security number.
What To Do If You Cannot Locate Your EIN
If you obtained an EIN years ago and cannot find the confirmation letter or any documents displaying it, the IRS still has the record. Call 1-800-829-4933 (the IRS Business and Specialty Tax Line) and provide your name, Social Security number, and the business address you used when you applied for the EIN. The IRS representative will look up your EIN in their system and provide it to you over the phone.
You can also request an IRS transcript that shows your EIN. Log into your IRS online account and select "View Your Tax Transcript." The transcript displays your EIN if one is associated with your account. If you do not have an online account, you can request a transcript by mail using Form 4506-C, though this takes 5 to 10 business days.
If you believe you obtained an EIN but cannot confirm it, the IRS can search their records using your name and business address. This search is free and takes a few minutes over the phone. Have your Social Security number and the year you think you applied for the EIN ready to speed up the search.
Documents That Display Your Tax ID Number
| Document Type | Who Issues It | When You Receive It |
|---|---|---|
| Form SS-4 Confirmation Letter | IRS | When you apply for an EIN |
| Individual Tax Return (Form 1040) | You (filed with IRS) | After you file your annual return |
| Business Tax Return (Form 1120 or 1120-S) | You (filed with IRS) | After you file your annual return |
| IRS Letter or Notice | IRS | In response to tax matters |
| W-2 Form (if you have employees) | You (issued to employees) | By January 31 each year |
| Business Bank Account Statement | Your bank | Monthly or on request |
| Tax Transcript | IRS | On request through IRS.gov or by mail |
Frequently Asked Questions
Is my tax ID number the same as my Social Security number?
Only if you are self-employed without employees and have never obtained an EIN. If you have a business with employees, a partnership, or a corporation, your tax ID is an EIN, not your Social Security number. You can have both — your Social Security number and a separate EIN for your business.
How do I know if I have an EIN?
Check your business bank account paperwork, past business tax returns, or any IRS letter about your business. If you filed a business tax return (Form 1120, 1120-S, or 1065), you used an EIN. If you only filed individual returns (Form 1040) with Schedule C for self-employment income, you used your Social Security number as your tax ID.
Can I look up someone else's tax ID number?
No. Tax ID numbers are confidential. The IRS will only provide a tax ID number to the person it belongs to or to an authorized representative with power of attorney. You cannot retrieve another person's number through IRS.gov or by calling the IRS.
What if I lost my EIN and need it right now?
Call the IRS Business and Specialty Tax Line at 1-800-829-4933. Representatives are available Monday through Friday, 7 a.m. to 7 p.m. your local time. Have your Social Security number and business information ready. The IRS can confirm your EIN over the phone in a few minutes.
Do I need to request a new EIN if I changed my business name?
No. Your EIN stays the same even if you change your business name. You do not need a new number — you just notify the IRS of the name change on your next tax return or by contacting them directly. Your EIN is tied to your business entity, not to the name you use.