Your Tax ID is on documents you already have at home

Your Tax ID — also called an EIN, ITIN, or SSN depending on your situation — appears on tax forms, bank statements, and official mail you've received from the IRS. You do not need to request it or contact anyone. If you filed taxes last year, look at your return first. If you have a business, check your EIN paperwork. If you're an immigrant without a Social Security number, your ITIN is on your most recent tax filing or IRS notice.

The document you're looking for depends on what type of Tax ID you need and whether you've already been assigned one. Most people have a Social Security number and don't need to search — they already know it. Others have an EIN for a business or an ITIN for tax purposes without a Social Security number. This guide walks you through where each one lives and what to do if you can't find it.

Key Takeaways

  • Your Social Security number appears on your tax return, W-2 forms, bank statements, and any IRS letter you've received.
  • An EIN for a business is on the IRS approval letter you received when you registered, or in your business tax return.
  • An ITIN for immigrants without a Social Security number is on your most recent tax return or any IRS notice sent to your address.
  • If you cannot find your number in these places, the IRS can confirm it by phone or mail using your name and date of birth.

Social Security Number — where it appears

Your Social Security number is printed on your Social Security card, which you received when you were born or when you first became a U.S. resident. If you still have the card, the nine-digit number is on the front. If you've lost the card, the number appears on almost every tax or financial document you've received.

Check these places in order: your most recent tax return (Form 1040 or 1040-SR), any W-2 form from an employer, a 1099 form from a bank or contractor, a mortgage statement, a car loan statement, or any letter from the IRS. If you filed taxes jointly with a spouse, your return shows both numbers. If you have a bank account, your statement usually shows your full Social Security number or the last four digits.

If none of these documents are available, you can request a replacement Social Security card from your local Social Security Administration office. Bring a photo ID and proof of citizenship or lawful residency. There is no charge for a replacement card.

EIN for a business — where to look first

An EIN (Employer Identification Number) is a nine-digit number assigned to your business by the IRS. If you registered a business and received approval, the IRS sent you a letter with the EIN on it. This letter, called a Form SS-4 approval notice, is the clearest place to find it.

If you don't have the approval letter, check your business tax return. If you filed a Form 1120 (for a corporation), Form 1120-S (for an S-corporation), Form 1065 (for a partnership), or Form 1040-C (for a sole proprietor), the EIN is at the top of the form. You can also find it on any business bank statement, business loan documents, or payroll records if your business has employees.

If you registered your business years ago and cannot locate the approval letter or tax return, the IRS can look up your EIN by phone. Call the IRS Business and Specialty Tax Line at 1-800-829-4933. Have your business name, address, and the date you registered ready. They will confirm the number and can mail you a new verification letter if you need one for a bank or lender.

ITIN for immigrants without a Social Security number

An ITIN (Individual Taxpayer Identification Number) is a nine-digit number issued by the IRS to people who are not may be able to access for a Social Security number but need to file taxes or open a bank account. If you have an ITIN, it appears on your most recent tax return in the same position where a Social Security number would go.

Check your last filed tax return (Form 1040 or 1040-SR), any IRS notice you received in the mail, or a letter from your tax preparer. The number looks like a Social Security number but starts with the digit 9. If you filed taxes more than one year ago, your ITIN is still valid — ITINs do not expire, though the IRS may require you to renew it if you have not filed in three years.

If you cannot find your ITIN in these places, contact the IRS at 1-800-829-1040 and ask for the Individual Taxpayer Identification Number line. Have your name, date of birth, and mailing address ready. The IRS can confirm your ITIN and mail you a verification letter. You can also visit an IRS office in person with your passport or national ID and a letter from a bank or employer requesting your ITIN.

What to do if you've lost or forgotten your number

If you've searched your documents and cannot find your Tax ID, do not panic. The IRS can look it up for you using only your name and date of birth. You have three ways to reach them: by phone, by mail, or in person at a local IRS office.

The fastest method is by phone. Call the IRS at 1-800-829-1040 (for personal tax matters) or 1-800-829-4933 (for business matters). Wait times are usually shorter early in the morning or late in the afternoon. Have your date of birth, current address, and a recent tax return or IRS letter ready. The agent will confirm your number and can mail you a verification letter if you need it for a bank, employer, or government agency.

If you prefer to write, send a letter to the IRS address for your state (found on any IRS notice you've received). Include your full name, date of birth, current address, and phone number. Ask them to confirm your Tax ID and mail it to you. Responses by mail usually take four to six weeks.

Tax ID verification letters from the IRS

Some banks, employers, and government agencies ask for proof of your Tax ID rather than the number itself. The IRS issues verification letters that confirm your number and your filing status. These letters are free and can be requested by phone, mail, or in person.

To request a verification letter by phone, call 1-800-829-1040 and tell the agent you need a letter verifying your Tax ID. They will mail it to your address on file within 7 to 10 business days. If you need it faster, visit your local IRS office in person with a photo ID and ask for an immediate verification letter — they can print one on the spot.

You can also request a verification letter by mail. Write to the IRS address for your state and include your name, Tax ID, date of birth, and a brief explanation of why you need the letter. The IRS will mail it within two to three weeks. Keep a copy for your records in case you need to show it again later.

Frequently Asked Questions

Can I look up someone else's Tax ID?

No. The IRS will only confirm a Tax ID to the person it belongs to or an authorized representative with power of attorney. If you need an employee's or contractor's Tax ID for payroll or tax reporting, ask them directly or request it through your payroll system.

What if my Tax ID was issued in a different state?

It does not matter. Social Security numbers, ITINs, and EINs are national and work the same way everywhere. Call the IRS at 1-800-829-1040 regardless of where you live or where the number was issued.

Do I need to memorize my Tax ID?

No. Write it down and store it somewhere safe at home — a drawer, a file, or a password-protected document. You do not need to carry it with you. When you need it, you can look it up at home or call the IRS to confirm it.

Is there a fee to get a replacement Tax ID or verification letter?

No. The IRS issues replacement Social Security cards, confirms Tax IDs, and mails verification letters at no cost. Be cautious of websites or services that charge money for these — they are scams.