What a Business Tax ID Is and Who Needs One

A Business Tax ID, officially called an Employer Identification Number (EIN), is a nine-digit number the IRS assigns to identify your business for tax purposes. The format is XX-XXXXXXX. You need one if you operate as a sole proprietorship with employees, a partnership, an S-corporation, a C-corporation, or an LLC — even if you have no employees yet. A sole proprietor with no staff can use their Social Security number instead, but most business owners get an EIN anyway because it separates personal and business finances on tax records.

The IRS issues EINs free of charge. You do not pay a fee to request one, and you do not need to hire a tax professional to obtain it. The process takes minutes online or up to four weeks by mail, depending on which method you choose.

Key Takeaways

  • You can get an EIN online through the IRS website in minutes, or by mail, phone, or fax if you cannot use the online system.
  • The IRS requires your legal business name, business address, the names and Social Security numbers or EINs of all owners, and the type of business structure you have.
  • Online applications are processed immediately; you receive your EIN the same day and can use it right away.
  • Mail and fax applications take two to four weeks, and phone applications take about 15 minutes but require calling during business hours.

Getting an EIN Online (Fastest Route)

The fastest way to get an EIN is through the IRS website at irs.gov/ein. Go to the "Apply for an EIN Online" page. You will need your legal business name, the principal business address (where you actually operate), your mailing address if different, and the name and Social Security number or EIN of the person who owns or manages the business.

The online form takes about 10 to 15 minutes to complete. You answer questions about your business structure (sole proprietorship, partnership, LLC, corporation, and so on), the type of work you do, and whether you have employees. At the end, the IRS issues your EIN immediately on screen. Write it down or print the confirmation page — you can use the number right away to open a business bank account, file taxes, or hire employees.

The online system is available Monday through Friday, 7 a.m. to 10 p.m. Eastern time. It is not available on weekends or federal holidays. If you try to apply outside those hours, you will see a message telling you to try again later or use a different method.

Getting an EIN by Mail, Phone, or Fax

If you cannot use the online system — for example, if you are applying on behalf of a trust or a non-resident alien — you can request an EIN by mail, phone, or fax. Each method has a different timeline.

By mail: Download Form SS-4 from irs.gov, fill it out by hand or type it, and mail it to the IRS address listed on the form. Processing takes two to four weeks. Mail the form to the address that corresponds to your state; the form itself lists the correct address.

By phone: Call the IRS Business and Specialty Tax Line at 1-800-829-4933. You will speak to a representative who will ask you the same questions as the online form. The call takes about 15 minutes. You receive your EIN verbally during the call and can write it down immediately. The phone line is open Monday through Friday, 7 a.m. to 10 p.m. Eastern time.

By fax: Fill out Form SS-4 and fax it to the IRS fax number for your state (listed on the form itself). Processing takes four to five business days. You do not receive the EIN by fax; instead, the IRS mails it to you, so this method is slower than phone or online.

Documents and Information You Need Before You Apply

Gather these items before you start your application, whether online, by phone, or by mail. Having them ready prevents delays and mistakes that can slow processing.

For all applications: your legal business name exactly as it appears on your business registration or formation documents; the principal business address (the physical location where you operate, not a P.O. box); your mailing address if it is different from the business address; the date you started or plan to start the business; and your business structure type (sole proprietorship, partnership, LLC, S-corp, C-corp, nonprofit, trust, and so on).

Owner information: the full name, Social Security number, and date of birth of each owner or member. If an owner is a business entity rather than an individual (for example, if an LLC is owned by a corporation), you need that entity's EIN instead of a Social Security number. If you are applying on behalf of someone else, you also need their title or relationship to the business.

Business description: a brief description of what your business does — for example, "plumbing contractor," "online retail," or "management consulting." This helps the IRS classify your business correctly for tax purposes.

What Happens After You Receive Your EIN

Once you have your EIN, you can use it immediately. Open a business bank account in the business name and EIN. Hire employees and set up payroll withholding. File business tax returns with the IRS. Apply for business licenses or permits that require a tax ID. Obtain a business credit line or business credit card.

The IRS does not send you a physical card or certificate. Your EIN is simply a number. If you need proof that you have one, you can print a confirmation letter from the IRS website. Go to irs.gov, search for "EIN Confirmation Letter," and follow the steps to request one. The letter arrives by mail in about two weeks, or you can print it immediately if you applied online.

Keep your EIN in a safe place. You will use it on every business tax return, W-2 form, and 1099 form you file. If you lose track of it, you can look it up on the IRS website or call the Business and Specialty Tax Line to confirm it.

When You Need to Request a New EIN

In most cases, you keep the same EIN for the life of your business. However, the IRS requires you to request a new EIN if your business structure changes — for example, if you convert a sole proprietorship to an LLC, or if a partnership dissolves and one partner continues the business alone. You also need a new EIN if you buy an existing business, because you are operating a separate legal entity even if you use the same business name.

If you simply change your business name, move to a new address, or change ownership while keeping the same structure, you do not need a new EIN. You just notify the IRS of the change on your next tax return or by calling the Business and Specialty Tax Line.

Frequently Asked Questions

How long does it take to get an EIN?

Online applications are processed immediately — you receive your EIN the same day. Phone applications take about 15 minutes, and you get the number during the call. Mail and fax applications take two to four weeks. If you need an EIN quickly, use the online system or call.

Can I get an EIN if I do not have a business address yet?

You need a physical business address to apply, not a P.O. box. If you are starting a home-based business, use your home address. If you are renting office space but have not moved in yet, you can use the address of the space you have reserved, as long as you have a lease or rental agreement showing the start date.

Do I need a business license before I request an EIN?

No. You can request an EIN before you have a business license. Many people get the EIN first, then use it to open a business bank account, and then file for local business licenses. The order depends on what your state and city require.

What if I made a mistake on my EIN application?

If you made a minor error — for example, a typo in your address — you can usually correct it by calling the Business and Specialty Tax Line or by notifying the IRS on your first tax return. If the error is major — for example, you listed the wrong business structure — you may need to request a new EIN. Call the IRS to ask whether correction or a new number is required.

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

If you are a sole proprietor with no employees, you can use your Social Security number on your tax return instead of an EIN. However, most business owners get an EIN anyway because it keeps personal and business finances separate on IRS records and looks more professional when dealing with banks and vendors.