What a Tax ID Is and Who Needs One

A Tax ID (also called an Employer Identification Number or EIN) is a nine-digit number the IRS uses to identify your business, nonprofit, or self-employment income. You need one if you operate a business, hire employees, or file certain tax forms — even if you work from home or run a side business alongside a regular job.

If you are self-employed as a sole proprietor with no employees, you may be able to use your Social Security number instead. But if you plan to hire anyone, form an LLC or corporation, or operate as a partnership, you must have a Tax ID. Many banks and vendors also require one before they will open a business account or issue a 1099 form.

The IRS issues Tax IDs for free. You do not pay to apply, and the number is permanent — you keep it even if you move, change your business name, or restructure your company.

Key Takeaways

  • You can get a Tax ID free from the IRS online, by mail, by fax, or by phone, and the process takes minutes to hours depending on which method you choose.
  • Online application through the IRS website (Form SS-4) is the fastest route and gives you your number immediately after you submit.
  • By mail or fax, you fill out the same form but wait one to two weeks for the IRS to mail your number back.
  • You need your Social Security number, business address, and the date you started or plan to start your business.
  • Once you have a Tax ID, you use it on all business tax forms, bank accounts, and vendor paperwork instead of your personal Social Security number.

Getting a Tax ID Online (Fastest Method)

The fastest way to get a Tax ID is through the IRS website using Form SS-4. You go to irs.gov, find the online EIN application tool, and fill out the form on screen. The entire process takes about 15 minutes. When you submit, the IRS gives you your Tax ID number right away — you can write it down or print the confirmation page.

To apply online, you need a valid Social Security number or ITIN, your business address, and the date your business started or will start. You also need to know your business structure (sole proprietor, LLC, S-corp, partnership, nonprofit, etc.) and what your business does. The IRS asks for this information to route your Tax ID to the right department.

After you receive your number online, the IRS mails a formal confirmation letter to your business address within two weeks. Keep that letter in your records. You can start using your Tax ID immediately — you do not have to wait for the letter to arrive.

Applying by Mail or Fax

If you cannot apply online, you can mail or fax Form SS-4 to the IRS. Download the form from irs.gov, fill it out by hand or on your computer, and either mail it to the address listed on the form or fax it to the fax number provided. The form itself is free.

By mail, the IRS typically sends your Tax ID back within one to two weeks. By fax, you may receive it within one business day, though this varies by location. Call the IRS at 1-800-829-4933 to confirm the fax number for your state before you send.

Keep a copy of the form you submit and note the date you sent it. If you do not hear back within the timeframe the IRS gives you, call to check the status.

Applying by Phone

You can also call the IRS Business and Specialty Tax Line at 1-800-829-4933 to request a Tax ID over the phone. An IRS representative will ask you the same questions that appear on Form SS-4 and issue your number during the call. You receive the number immediately and can use it right away.

Phone lines are typically busiest in the morning and during tax season (January through April). Call early in the day or outside tax season if you can. Have your Social Security number, business address, and business start date ready before you call.

Documents and Information You Will Need

Regardless of which method you choose, have the following ready before you start:

  • Your Social Security number or ITIN
  • Your business address (street, city, state, ZIP code)
  • The date your business started or will start
  • Your business structure (sole proprietor, LLC, S-corp, C-corp, partnership, nonprofit, trust, estate, etc.)
  • A description of what your business does
  • The name of the person responsible for the business (usually you)

If you are applying on behalf of a business you do not own (for example, as a representative of a nonprofit or partnership), you may need additional paperwork showing your authority to apply. The IRS will tell you if this is required.

What Happens After You Get Your Tax ID

Once you have your Tax ID, use it on all business tax forms, bank accounts, vendor accounts, and any paperwork that asks for an employer identification number. Do not share it publicly or use it for personal matters — it is for your business only.

You will use your Tax ID when you file your business tax return each year, hire employees, open a business bank account, and apply for business licenses or permits. Keep your Tax ID number and the IRS confirmation letter in a safe place. You will need them throughout the life of your business.

If your business closes, you do not need to cancel your Tax ID. The IRS will mark it as inactive if you stop filing returns, but the number remains yours if you restart the business later.

Frequently Asked Questions

How long does it take to get a Tax ID?

Online is fastest — you get your number immediately when you submit the form. By fax, you may receive it within one business day. By mail, expect one to two weeks. By phone, you get it during the call.

Can I use my Social Security number instead of a Tax ID?

If you are a sole proprietor with no employees, you can use your Social Security number on your tax return. However, many banks and vendors require a Tax ID before they will open a business account or issue a 1099 form, so getting one is usually necessary even if not legally required.

Do I need a Tax ID if I am self-employed?

Not always. If you work alone as a sole proprietor and do not hire anyone, you can report self-employment income using your Social Security number. But if you plan to hire even one person, form an LLC, or operate as a partnership, you must have a Tax ID.

What if I already have a Tax ID but forgot the number?

Call the IRS at 1-800-829-4933 with your Social Security number and business name. They can look up your Tax ID for you. You can also check old tax returns or bank statements — your Tax ID appears on both.

Can I get a Tax ID if I do not have a Social Security number?

Yes. If you have an ITIN (Individual Taxpayer Identification Number), you can use that instead. Apply the same way — online, by mail, by fax, or by phone — and provide your ITIN where the form asks for a Social Security number.