You get an EIN from the IRS, usually the same day you apply online

An Employer Identification Number (EIN) is a nine-digit code the IRS uses to identify your business for tax purposes. You need one if you have employees, operate as a corporation or partnership, or file certain business tax returns. The IRS issues EINs for free through their website, by phone, by fax, or by mail — and the online method gives you a number immediately after you finish the form.

You do not need an EIN if you are a sole proprietor with no employees and no business structure (like an LLC or S-corp). In that case, you can use your Social Security number on tax forms instead. But if you have any doubt, getting an EIN costs nothing and takes minutes online, so most business owners do it anyway.

Key Takeaways

  • The IRS Form SS-4 is the only form you need to request an EIN, and you can submit it online at irs.gov for an immediate number.
  • You must have a valid Social Security number or Individual Taxpayer Identification Number (ITIN) to apply, and you need to know your business structure (sole proprietor, LLC, corporation, partnership, etc.).
  • Online applications are processed instantly; phone applications (1-800-829-4933) take a few minutes; mail and fax applications take two to four weeks.
  • Once you receive your EIN, you use it on all business tax forms, bank accounts, and payroll documents — you do not need to renew it or reapply.

What information you need before you start

Have these details ready before you fill out Form SS-4, whether you apply online or by another method. You will need your Social Security number or ITIN, your legal business name (exactly as it appears on your business registration or formation documents), and your business address. If your business is a corporation, partnership, or LLC, you also need to know your business structure type.

If you are applying on behalf of someone else's business — for example, as a representative or officer — you will need that person's name, title, and Social Security number or ITIN as well. The IRS also asks what your business does, so have a brief description ready (for example, "plumbing contractor" or "retail clothing store"). You do not need to have filed any paperwork with your state yet, but you do need to know whether you have already done so.

How to apply online for an immediate EIN

Go to irs.gov and search for "apply for an EIN online." The IRS online application is called the EIN Assistant, and it walks you through Form SS-4 step by step. You will answer questions about your business structure, the reason you need an EIN (hiring employees, opening a bank account, filing a return, etc.), and your business details. The form takes about 10 to 15 minutes to complete.

When you submit the form online, the IRS generates your EIN on the screen immediately. Write it down or print the confirmation page — you will need it to open a business bank account and file tax returns. The IRS will also email you a confirmation, though sometimes that email takes a few hours to arrive. You can start using your EIN right away; you do not have to wait for anything in the mail.

Applying by phone, fax, or mail if you cannot go online

If you cannot use the online tool, you can call the IRS Business and Specialty Tax Line at 1-800-829-4933 during business hours (Monday through Friday, 7 a.m. to 10 p.m. Eastern time). A representative will ask you the same questions as the online form and issue your EIN over the phone. The call usually takes 5 to 10 minutes, and you will have your number before you hang up.

You can also fax or mail a completed Form SS-4 to the IRS. The address and fax number are on the form itself, which you can download from irs.gov. Faxed applications are usually processed within two to four business days; mailed applications take two to four weeks. You will receive your EIN by mail at the address you provide on the form. This method is slower but works if you have no internet access or phone service.

What happens after you receive your EIN

Once you have your EIN, use it on all business tax forms, W-4 forms for employees, business bank account applications, and any other documents that ask for a tax ID. You do not need to register it anywhere else or take any additional steps — the IRS has your information on file. Your EIN never expires and never changes, even if you move, change your business name, or restructure your business (though some changes do require you to notify the IRS separately).

Keep your EIN in a safe place. You will need it every year to file business tax returns, and you will give it to your bank, accountant, and employees. If you lose it, you can look it up on irs.gov or call the IRS to confirm the number they have on file for your business.

Situations where you might need to apply again

In most cases, you apply for an EIN once and keep it for the life of your business. However, if your business structure changes — for example, you convert from a sole proprietorship to an LLC, or you merge with another business — you may need a new EIN. The same is true if your business is sold or transferred to new ownership. The IRS website has guidance on when a change requires a new EIN; when in doubt, contact the IRS or speak with a tax professional.

If you close your business, you do not need to do anything with your EIN. You simply stop using it. If you start a new business later, you can apply for a new EIN for that business using the same process.

Frequently Asked Questions

Do I need an EIN if I am a sole proprietor with no employees?

No, you can use your Social Security number on tax forms instead. However, many sole proprietors get an EIN anyway to keep their personal and business finances separate, especially if they plan to hire employees later or open a business bank account. Getting one costs nothing and takes minutes, so it is a common choice even when not required.

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

Mailed applications usually take two to four weeks. If you need your EIN sooner, apply online (instant) or by phone (5 to 10 minutes). Faxed applications are processed in two to four business days, which is faster than mail but slower than online or phone.

Can I apply for an EIN before I officially register my business with the state?

Yes. You do not need state registration to apply for an EIN. However, you do need to know your intended business structure (sole proprietor, LLC, corporation, etc.) and have a business name and address ready. Many people apply for an EIN before filing state paperwork.

What if I already have an EIN but forgot the number?

You can look it up on irs.gov using your business name and address, or call the IRS Business and Specialty Tax Line at 1-800-829-4933. Have your business information ready when you call. You do not need to apply again — the IRS will confirm the number they have on file.

Can someone else apply for an EIN on my behalf?

Yes. A representative, officer, or authorized person can apply for an EIN for your business. You will need to provide that person with your Social Security number or ITIN, your legal business name, and your business address. They can then apply online, by phone, or by mail using Form SS-4.