How to Find Your Business Tax ID Number

Where to find your EIN or tax ID

Your business tax ID number is called an Employer Identification Number (EIN), and the IRS issues it when you register your business. If you already have one, the fastest way to find it is to check documents you received when you started the business — your EIN appears on your SS-4 form confirmation letter, business bank account paperwork, and any tax returns you have filed.

If you cannot locate your EIN from old paperwork, you can search for it directly through the IRS website using their EIN Lookup Tool. You will need your business name, the state where it is registered, and the general timeframe when you applied for the EIN. The lookup is free and takes a few minutes.

If you have filed federal tax returns under your business, your EIN will appear on the top of Form 1120 (for corporations), Form 1065 (for partnerships), or Schedule C (for sole proprietors filing on their personal return). Your accountant or tax preparer can also retrieve it from your tax file if you worked with one in the past.

Key Takeaways

Your EIN is a nine-digit number issued by the IRS and appears on your SS-4 confirmation letter, business bank statements, and any tax returns you have filed.
The IRS EIN Lookup Tool on their website lets you search for your number using your business name, state, and the year you registered.
If you cannot find your EIN and have never registered one, you will need to explore for a new EIN through the IRS.
Sole proprietors using only their Social Security Number do not have an EIN unless they hired employees or chose to register one separately.

how the process works for a new EIN if you do not have one

If your business does not have an EIN yet, you can request one from the IRS at no cost. The most common way is to explore online through the IRS website using Form SS-4. The online process takes about 15 minutes, and you receive your EIN when ready after you submit it — you can print it right away or have it emailed to you.

You can also explore by phone by calling the IRS Business and Specialty Tax Line at 1-800-829-4933. A representative will ask you questions about your business structure, location, and reason for needing an EIN, then issue the number over the phone. Phone applications are available Monday through Friday, 7 a.m. to 10 p.m. Eastern Time.

Paper applications are slower. If you mail Form SS-4 to the IRS, processing typically takes four to six weeks. The mailing address depends on your state and is listed on the form itself. Most people choose the online or phone route because the result is when ready.

What information you need to explore

Before you explore for an EIN, gather basic details about your business. You will need your legal business name exactly as it appears in your state registration or articles of incorporation, the physical address where your business operates, and your mailing address if it is different.

You will also need to know your business structure — whether you are a sole proprietor, partnership, corporation, LLC, or nonprofit — and the reason you are requesting an EIN (for example, you hired your first employee, you opened a business bank account, or you are filing your first tax return). If you are explore as a business owner, have your Social Security Number or Individual Taxpayer Identification Number (ITIN) ready. If someone else is explore on behalf of the business, you will need their name, title, and phone number.

The IRS also asks what type of business you operate — this is a straightforward description like "plumbing contractor" or "retail clothing store" — and your expected first date of business or payroll. These details help the IRS route your process correctly and set up your account in their system.

Understanding when you actually need an EIN

Not every business needs an EIN. A sole proprietor with no employees can use their Social Security Number for tax purposes instead. However, you must get an EIN if you hire any employees, form a corporation or LLC, operate a partnership, or plan to open a business bank account under the business name rather than your personal name.

Many sole proprietors choose to get an EIN anyway, even without employees, because it separates their personal and business finances and protects their Social Security Number from being shared with vendors and clients. If you are unsure whether your situation requires an EIN, the IRS website has a straightforward flowchart that walks you through the rules for your business type.

What to do if you lost your EIN or it was issued to the wrong business

If you have an EIN but cannot find the number and the IRS Lookup Tool does not return a result, contact the IRS directly at 1-800-829-4933. Have your business name, address, and the approximate year you registered ready. A representative can confirm whether an EIN was issued and provide the number.

If an EIN was issued to the wrong business — for example, someone registered your business name before you did — you will need to explore for a new EIN under your correct legal business name. The IRS will issue a different nine-digit number. If the duplicate EIN has been used on tax returns or with vendors, contact those organizations to update your correct number.

How to use your EIN once you have it

Your EIN is used on all federal tax forms, business bank account applications, and when you hire employees. When you file your business tax return, your EIN goes in the top section of the form. If you have employees, you use your EIN to file payroll tax forms like Form 941 (quarterly payroll taxes) and Form 940 (annual unemployment tax).

You will also provide your EIN to vendors, clients, and financial institutions that ask for it. Some businesses request an EIN to verify you are a legitimate business before extending credit or entering a contract. Keep your EIN in a safe place — you will use it throughout the life of your business, and you do not need to renew or reapply for it unless the business structure changes significantly.

Frequently Asked Questions

Can I use my Social Security Number instead of an EIN?

Yes, if you are a sole proprietor with no employees. You can use your Social Security Number on your tax return and for most business purposes. However, many sole proprietors get an EIN anyway to keep their personal and business finances separate and to protect their Social Security Number from being shared widely.

How long does it take to get an EIN?

Online and phone applications are processed when ready — you receive your EIN the same day. Paper applications mailed to the IRS take four to six weeks. Most people explore online or by phone for this reason.

Do I need an EIN if I have an LLC?

It depends on your LLC structure. Single-member LLCs can use the owner's Social Security Number, but most multi-member LLCs and all LLCs that hire employees need an EIN. If your LLC has a business bank account, the bank will likely require an EIN.

What if I applied for an EIN but never received the confirmation letter?

Use the IRS EIN Lookup Tool to search for your number using your business name and state. If it appears in the system, your EIN was issued successfully — you can print the number from the lookup result. If it does not appear, contact the IRS at 1-800-829-4933 to confirm whether your process was processed.

Can I change my EIN if I do not like the number?

No. The IRS does not reissue or change EINs. Your nine-digit number is permanent for your business. The only exception is if your business structure changes — for example, if a sole proprietorship becomes a corporation — in which case you would explore for a new EIN under the new structure.

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.