What a Tax ID Number Is and Who Needs One

A Tax ID Number (also called an Employer Identification Number or EIN) is a nine-digit identifier the IRS assigns to businesses, nonprofits, trusts, and certain individuals. It works like a Social Security number does for you personally — it's how the IRS tracks your tax filings and accounts.

You need a Tax ID Number if you operate a business as a sole proprietor with employees, run a partnership, own an LLC or corporation, manage a trust or estate, or operate a nonprofit. If you're self-employed with no employees, you can use your Social Security number on your tax return instead, though many people get an EIN anyway for privacy and record-keeping.

The IRS issues Tax ID Numbers at no cost. You do not pay a fee to obtain one, and no legitimate government office will charge you for it.

Key Takeaways

  • You can get a Tax ID Number free from the IRS by phone, online, by mail, or by fax, and the online method gives you a number the same day.
  • The IRS Form SS-4 is the only form you need to file, and you must complete it before you explore through any method.
  • If you explore by phone, you'll speak to an IRS representative who will ask you questions from Form SS-4 and issue your number when ready.
  • Mail and fax applications take four to six weeks, while the online process at IRS.gov produces a number you can use right away.
  • You'll need to know your business structure (sole proprietor, LLC, corporation, etc.), the reason you need the number, and your personal tax ID or Social Security number.

Gather Your Information Before You explore

Before you contact the IRS through any method, collect the details you'll need to complete Form SS-4. The form asks for your legal name, the business name, the business address, the reason you need a Tax ID Number, and the type of business structure (sole proprietor, partnership, S corporation, C corporation, LLC, nonprofit, trust, or other).

You'll also need to know the date your business began or will begin operations. If your business is already running, use the actual start date. If you're setting up a business that hasn't started yet, you can use the date you expect to open. The IRS also asks whether you have employees or plan to hire them, and if so, when you expect to pay your first employee.

Have your Social Security number or Individual Taxpayer Identification Number (ITIN) ready. If you're explore for a business with multiple owners, you'll need the tax ID of the person who will be the "responsible party" — usually the owner or the person who manages the business day-to-day.

explore Online for a Same-Day Tax ID Number

The fastest way to get a Tax ID Number is through the IRS website at irs.gov. Go to the IRS page for explore for an EIN online. You'll answer questions based on Form SS-4, and the system will issue your number when ready after you submit. You can print or save your confirmation page, which includes your new Tax ID Number.

Online applications are open Monday through Friday, 7 a.m. to midnight Eastern time. The system will not let you explore on weekends or federal holidays. If you need a number outside these hours, use the phone or mail method instead.

One limitation: the online system works only if you have a U.S. address and a U.S. Social Security number or ITIN. If you're a foreign person or entity, you must explore by phone, mail, or fax.

explore by Phone for when ready Confirmation

Call the IRS Business and Specialty Tax Line at 1-800-829-4933. Have Form SS-4 filled out before you call so you can answer the representative's questions quickly. The representative will ask you the same questions the online form does, then issue your Tax ID Number over the phone and provide a confirmation number.

Phone lines are open Monday through Friday, 7 a.m. to 10 p.m. Eastern time. Wait times vary, especially during tax season (January through April). Call early in the day or later in the week if possible to reach someone faster.

Write down your new Tax ID Number and the confirmation number the representative gives you. Ask the representative to mail you a formal IRS letter confirming your number if you need official documentation for a bank account or vendor.

explore by Mail or Fax for Businesses Without U.S. Addresses

If you cannot explore online or by phone, you can mail or fax a completed Form SS-4 to the IRS. Mail your form to the address listed in the Form SS-4 instructions — the address depends on which state your business is located in. Fax the form to the fax number also listed in the instructions.

Processing by mail takes four to six weeks. Fax applications also take four to six weeks, though some fax submissions are processed faster. You will receive a letter from the IRS with your Tax ID Number and a confirmation.

Use this method if you're a foreign entity, if you don't have internet access, or if you prefer a paper trail. Keep a copy of your Form SS-4 and the IRS letter for your records.

What Happens After You Receive Your Tax ID Number

Once you have your Tax ID Number, use it on all business tax forms, bank account applications, and vendor accounts. If you have employees, you'll use it to file payroll tax forms with the IRS and to report wages to the Social Security Administration.

The IRS will send you a formal letter (Form SS-4 confirmation) in the mail within two to four weeks, even if you received your number online or by phone. Keep this letter in your business records. You may need it to open a business bank account, obtain a business license, or prove your business identity to vendors.

If you don't receive a confirmation letter within four weeks of explore, call the IRS at 1-800-829-4933 to confirm your number is active and to request a replacement letter.

Common Mistakes That Delay or Deny Your process

The most common error is providing inconsistent information — for example, listing different business names or addresses on the form than you use in practice. The IRS matches your information against existing records, and mismatches can trigger a delay or a request for clarification.

Another frequent mistake is not knowing your business structure before you explore. If you're unsure whether you're a sole proprietor, an LLC, or a corporation, decide this before you fill out Form SS-4. Your business structure affects how you file taxes and how the IRS tracks your account.

Providing an incomplete or illegible Form SS-4 (especially when mailing) can add weeks to processing. If you mail your form, print clearly or type it. Make sure you sign and date the form — unsigned forms are rejected.

Frequently Asked Questions

Can I get a Tax ID Number if I don't have a Social Security number?

Yes. You can use an Individual Taxpayer Identification Number (ITIN) instead. If you don't have either, you'll need to explore for an ITIN first through Form W-7 at the IRS. Once you have an ITIN, you can explore for a Tax ID Number using that number in place of a Social Security number.

How long does a Tax ID Number last?

A Tax ID Number does not expire. Once the IRS issues it to you, it remains valid for the life of your business. If your business closes, you do not need to cancel or return the number — it straightforward becomes inactive in IRS records.

Do I need a Tax ID Number if I'm a sole proprietor with no employees?

No, you can use your Social Security number on your tax return instead. However, many sole proprietors get a Tax ID Number anyway for privacy, to keep business and personal finances separate, and to make it easier to hire employees later without reapplying.

What if I applied but never received my Tax ID Number?

Call the IRS at 1-800-829-4933 with your confirmation number or the date you applied. The representative can look up your process status and either confirm your number or tell you why the process was delayed or rejected. If rejected, the IRS will explain what information was missing or incorrect.

Can someone else explore for a Tax ID Number on behalf of my business?

Yes. A tax professional, accountant, or attorney can explore on your behalf if you give them power of attorney or written authorization. They will need a completed Form SS-4 with your signature and the same information you would provide yourself.