Where to Find Your Tax ID Number

Your Tax ID is on documents you already have

Your Tax ID number — also called an Employer Identification Number (EIN) or Social Security Number (SSN) — appears on tax forms, bank statements, and official mail from the IRS. You do not need to request it or search a government database. The number was assigned to you when you filed your first tax return or opened a business, and it stays the same unless you deliberately change it.

If you are an individual filing taxes, your Tax ID is your Social Security Number. If you own a business or operate as a sole proprietor, you may have both an SSN and a separate EIN. The fastest way to find either one is to look at documents you have already received from the IRS or your employer.

Key Takeaways

Your Social Security Number is your Tax ID if you file as an individual; your EIN is a separate nine-digit number assigned only if you own a business.
Check your most recent tax return, W-2 form, or 1099 form — your Tax ID appears on all of them.
If you have a business, your EIN letter from the IRS contains your nine-digit number and should be kept with your business records.
The IRS website allows you to look up an EIN you have already been assigned, but you cannot search for a number you do not remember.

Where to look first: documents in your possession

Start with paperwork you have received from your employer or the IRS. Your Tax ID appears on:

Your most recent tax return (Form 1040, 1040-SR, or 1040-NR) — your SSN is in the top right corner
Your W-2 form from your employer — your SSN appears in box a
Your 1099 form (1099-NEC, 1099-MISC, 1099-INT, or other variants) — your SSN or EIN is listed at the top
Your Social Security card — your nine-digit SSN is printed on the face
Your driver's license or state ID — does not show your SSN, but confirms your identity if you need to contact the IRS

If you own a business, you also received an EIN Assignment Letter (Form SS-4) from the IRS when your business was registered. This letter contains your nine-digit EIN and the date it was assigned. Keep this letter with your business tax records; you will need it to file business returns and open a business bank account.

Using the IRS website to confirm your EIN

If you own a business and have lost your EIN Assignment Letter, you can look up the number on the IRS website. Go to irs.gov and search for "EIN lookup." The tool allows you to enter your business name and other details to retrieve an EIN that has already been assigned to you.

This lookup tool works only if you have already been assigned an EIN. You cannot use it to search for a number you do not remember or to check whether a number exists. If you cannot find your EIN through the lookup tool and do not have your assignment letter, you will need to contact the IRS directly by phone or mail.

Contacting the IRS if you cannot locate your number

If you have looked through your documents and cannot find your Tax ID, call the IRS at 1-800-829-1040. Have your name, date of birth, and current address ready. The IRS representative will confirm your identity and provide your SSN or EIN over the phone.

If you own a business, you can also write to the IRS at the address listed on any tax notice you have received. Include a copy of your driver's license or passport and explain that you need your EIN. The IRS will mail your EIN Assignment Letter to you, though this method takes several weeks.

Do not call the IRS during tax season (January through April) unless your situation is urgent — wait times are long. Outside tax season, you can usually reach someone within 15 to 30 minutes.

What to do if you think your Tax ID has been compromised

If you believe someone has used your Social Security Number or EIN fraudulently, contact the IRS immediately. Call 1-800-829-1040 and ask to speak with a representative about identity theft. The IRS can place a fraud alert on your account and issue you a new SSN if necessary, though this is rare and takes time.

You should also file a report with the Federal Trade Commission (FTC) at identitytheft.gov. The FTC will create a record of the theft and provide you with a recovery plan. If fraudulent tax returns have been filed in your name, the IRS will contact you by mail with next steps.

Difference between SSN and EIN

Your Social Security Number (SSN) is a nine-digit number assigned to you at birth or when you first work in the United States. It is your personal Tax ID and is used on all individual tax returns. You have one SSN for life unless you report identity theft.

Your Employer Identification Number (EIN) is a separate nine-digit number assigned only to businesses, partnerships, corporations, nonprofits, and trusts. If you are self-employed as a sole proprietor, you may not have an EIN — you can file taxes using only your SSN. If you hire employees or form a business entity, you must obtain an EIN. A business can have multiple EINs if it has multiple locations or entities, but each EIN is tied to one business structure.

Frequently Asked Questions

Is my Tax ID the same as my Social Security Number?

If you file taxes as an individual, yes — your SSN is your Tax ID. If you own a business, you have both an SSN (personal) and an EIN (business). The EIN is separate and used only for business tax returns and accounts.

Can I change my Tax ID number?

You cannot change your SSN unless you report identity theft to the IRS and Social Security Administration. You can request a new EIN for a business if you change the business structure or ownership, but the old EIN remains on file with the IRS.

What if I lost my Social Security card?

You do not need the physical card to know your SSN — it appears on your tax return, W-2, or 1099. If you need a replacement card, contact the Social Security Administration at ssa.gov or visit a local Social Security office. You can order a replacement card online in most states.

Do I need an EIN if I am self-employed?

Not necessarily. If you are a sole proprietor with no employees, you can file taxes using your SSN. You only need an EIN if you hire employees, form an LLC or corporation, or operate as a partnership or nonprofit.

How long does it take to get an EIN?

If you apply online at irs.gov, you receive your EIN immediately. If you apply by phone, mail, or fax, it takes one to two weeks. You can begin using your EIN as soon as it is assigned, even if you have not received the assignment letter yet.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.