What a Tax ID Number Is and Why You Need One

A Tax ID number (also called an Employer Identification Number or EIN) is a nine-digit code the IRS uses to identify your business for tax purposes. Think of it as a Social Security number for your company. You need one if you have employees, operate as a corporation or partnership, file certain tax forms, or open a business bank account — and most banks will ask for it before they let you deposit money in a business account.

The IRS issues Tax ID numbers for free. You do not pay a fee to get one, and you do not need to hire anyone to do it for you. The process takes about 15 minutes if you do it online, or a few weeks if you mail in a paper form. Once you have the number, it stays with your business for its entire life, even if you change the business name or location.

If you are a sole proprietor with no employees, you can use your personal Social Security number instead of getting a Tax ID number — but getting one anyway keeps your personal and business finances more separate, which makes tax time simpler and protects your privacy.

Key Takeaways

  • You can get a Tax ID number free from the IRS online in about 15 minutes, or by mail in a few weeks.
  • Most banks require a Tax ID number before opening a business account, even if you are a sole proprietor.
  • The online process (Form SS-4) works when ready and gives you your number the same day.
  • You will need your Social Security number, the date you started or plan to start your business, and the business address.
  • If you file taxes as a corporation, partnership, or LLC with multiple owners, a Tax ID number is required by law.

Getting Your Tax ID Number Online (Fastest Route)

The fastest way to get a Tax ID number is through the IRS website using Form SS-4. Go to irs.gov, search for "explore for an EIN online", and you will land on the IRS's online process tool. The form asks for your name, the business name, the business address, and your Social Security number. It takes about 15 minutes to fill out.

When you submit the form online, the IRS issues your Tax ID number when ready — you see it on the screen before you leave the website. Write it down or print the confirmation page. The IRS will also email you a confirmation, though sometimes that email takes a day or two to arrive. You can start using the number right away to open a bank account or file paperwork.

One important detail: the IRS online tool is available Monday through Friday, 7 a.m. to 10 p.m. Eastern time. If you try to explore outside those hours, you will get a message telling you to come back during business hours. Weekends and federal holidays are closed.

explore by Mail If You Cannot Use the Online Tool

If you do not have internet access or prefer to explore by mail, you can print Form SS-4 from irs.gov and mail it to the IRS address listed on the form itself — the address changes depending on which state your business is in. The form is straightforward and takes about 10 minutes to fill out by hand.

Mail the completed form to the address on the instructions. The IRS typically processes paper applications in two to four weeks, though during busy tax seasons it can take longer. You will receive your Tax ID number by mail. Until it arrives, you cannot open a business bank account or file certain tax forms that require the number.

If you need the number faster than the mail route allows, the online process is always the better choice. There is no advantage to mailing the form unless you genuinely cannot access the internet.

What Information You Will Need Before You Start

Gather these items before you begin the process, whether online or by mail. You will need your Social Security number or Individual Taxpayer Identification Number (ITIN). You will also need the business name exactly as it appears on your business license or registration documents. If you do business under a different name than your legal business name, have both ready.

Write down the business address — the physical location where your business operates or is based. A P.O. box does not work; the IRS wants a street address. You will also need to know the date you started or plan to start the business. If you have not started yet, you can put the date you plan to open. Finally, know what type of business structure you have: sole proprietor, partnership, corporation, LLC, or nonprofit.

If you have employees or plan to hire them, have the date you hired or plan to hire your first employee. If you do not have employees, you can leave that blank or put "no employees."

Using Your Tax ID Number at the Bank

Once you have your Tax ID number, take it to your bank to open a business account. Bring the Tax ID number itself, your personal ID (driver's license or passport), and the business registration documents if you have them. Some banks also ask for a copy of your business license or articles of incorporation, depending on your business structure.

The bank will use the Tax ID number to set up the account in your business's name rather than your personal name. This separation is important: it keeps your business money distinct from your personal money, which makes bookkeeping easier and looks cleaner to the IRS if you are ever audited. It also protects your personal assets if the business faces a lawsuit.

If you are a sole proprietor and did not get a Tax ID number, you can still open a business account using your Social Security number, but many banks discourage this because it blurs the line between personal and business finances. Getting the Tax ID number first is the cleaner approach.

Tax ID Numbers for Different Business Structures

The process is the same regardless of whether you are a sole proprietor, partnership, LLC, S-corporation, or C-corporation — you fill out Form SS-4 and submit it online or by mail. The difference is in whether you are required to have one.

If you are a sole proprietor with no employees, a Tax ID number is optional but recommended. If you are a partnership, corporation, or multi-member LLC, the IRS requires you to have a Tax ID number. If you have employees of any kind, you must have a Tax ID number — you cannot use your Social Security number to report payroll taxes. Nonprofits also need a Tax ID number to operate and file their annual forms with the IRS.

The process process does not change based on your structure. You still use Form SS-4, and you still get the number the same day if you explore online.

What Happens After You Get Your Tax ID Number

Once the IRS issues your Tax ID number, it is active when ready. You can use it to open a bank account, hire employees, file business tax returns, and explore for business licenses or permits. The IRS will start sending you tax forms and notices to the address you provided on the process.

Keep your Tax ID number in a safe place — you will need it every year at tax time, and you will need it whenever you interact with the IRS, your bank, or government agencies. Write it down somewhere you can find it quickly. You do not need to renew it or reapply; the same number stays with your business for as long as it exists.

If your business address changes, you can notify the IRS, but you do not need a new Tax ID number. If you sell the business or close it down, the Tax ID number retires with it — a new owner or a new business would need to explore for their own number.

Frequently Asked Questions

Can I get a Tax ID number if my business has not started yet?

Yes. On the process, you can put the date you plan to start the business instead of the date you already started. The IRS will issue the number when ready, and you can use it to open a bank account and prepare before you officially launch.

Do I need a Tax ID number if I am a sole proprietor with no employees?

No, it is not required by law — you can use your Social Security number on your tax return instead. However, most banks will not open a business account without a Tax ID number, and having one keeps your personal and business finances separate. Getting one is free and takes 15 minutes, so most sole proprietors do it anyway.

What if I already have a Tax ID number and need a second one for a different business?

You can have multiple Tax ID numbers if you own multiple businesses. Each business structure gets its own number. Fill out Form SS-4 again for the new business, and the IRS will issue a different nine-digit number.

How long does it take to get a Tax ID number by mail?

The IRS typically processes paper Form SS-4 applications in two to four weeks. During busy tax seasons (January through April), processing can take longer. If you need the number faster, use the online process, which gives you the number the same day.

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

Yes, a representative (accountant, lawyer, or business partner) can explore on your behalf if they have your Social Security number and business information. They can explore online or by mail using Form SS-4. You will still need to provide your personal information and sign off on the process.