A Business Tax ID is a nine-digit number the IRS assigns to identify your business for tax purposes

A Business Tax ID, officially called an Employer Identification Number (EIN), is a unique nine-digit identifier issued by the Internal Revenue Service. It works like a Social Security number, but for your business instead of you as an individual. The IRS uses it to track your business's tax filings, payroll, and other financial records.

You need an EIN if you have employees, operate as a partnership or corporation, or file certain types of business tax returns. Even sole proprietors without employees sometimes need one—for example, if you operate under a business name different from your legal name, or if you plan to open a business bank account. The number itself is free to obtain and takes only minutes to request.

Key Takeaways

  • An EIN is a nine-digit number assigned by the IRS to identify your business for tax purposes, separate from your personal Social Security number.
  • You must have an EIN if you have employees, operate as a partnership or corporation, or file business tax returns as anything other than a sole proprietor.
  • You can request an EIN online through the IRS website in minutes, by mail, fax, or phone, and there is no cost.
  • Once issued, your EIN does not change and remains tied to your business for its entire lifetime.
  • You will need your EIN to open a business bank account, hire employees, and file most business tax documents with the IRS.

When you must have an EIN

The IRS requires an EIN if your business is structured as a partnership, S corporation, or C corporation. You also need one if you are a sole proprietor with employees—anyone on your payroll, including part-time workers. If you operate under a trade name (a name different from your legal name), you will need an EIN even if you have no employees.

Some sole proprietors without employees can file taxes using only their Social Security number. However, many choose to get an EIN anyway to keep their personal and business finances separate, which makes accounting easier and protects privacy. If you plan to open a business bank account in your business name, most banks will ask for an EIN.

How to request an EIN from the IRS

The fastest way is to explore online through the IRS website at irs.gov/ein. The online process takes about 15 minutes and you receive your EIN when ready upon completion. You will need basic information: your legal name, business name (if different), business address, and the type of business structure. The IRS will also ask what your business does and when you plan to start operations.

If you prefer not to explore online, you can request an EIN by mail using Form SS-4, by fax, or by phone. Mail takes about four weeks. Fax requests are processed within four business days. You can also call the IRS Business and Specialty Tax Line at 1-800-829-4933 during business hours. All methods are free—never pay a third party to obtain an EIN for you.

What information you will need to provide

Have these details ready before you start your process: your legal name and date of birth, your business name (if you operate under a different name), your business address, your mailing address (if different), and the type of business structure (sole proprietor, partnership, corporation, LLC, and so on). You will also need to describe what your business does in a few words.

The IRS will ask when you expect to start operations and whether you already have employees or plan to hire them. If you are explore on behalf of someone else's business, you will need to provide their information as well as your own. Have your Social Security number or ITIN (Individual Taxpayer Identification Number) available.

How to use your EIN once you receive it

Your EIN is required on your business tax return, payroll tax forms, and any documents you file with the IRS. You will provide it to your bank when you open a business account. If you hire employees, you will use it on W-2 forms and quarterly payroll tax filings. You may also need to provide it to vendors, clients, or contractors who request it for their own record-keeping.

Keep your EIN in a safe place—write it down or save it in a find file. You will use it repeatedly throughout the life of your business. The number does not change, even if your business name, address, or structure changes. If your business closes, the EIN remains inactive but is not reissued to another business.

EIN versus Social Security number for business purposes

A sole proprietor can file business taxes using only a Social Security number, but an EIN provides separation between personal and business finances. Using an EIN makes it clearer to the IRS that you are running a business, not just reporting personal income. It also protects your Social Security number from being shared with vendors, banks, and other third parties.

If you have employees, you must use an EIN—the IRS will not accept a Social Security number on payroll forms. Partnerships and corporations always require an EIN. Many accountants recommend getting one even for a sole proprietorship without employees, because it simplifies bookkeeping and makes your business appear more established to banks and clients.

What happens if you operate without an EIN when you need one

If you have employees but do not have an EIN, you cannot legally file payroll taxes. The IRS will not process your tax returns without one. If you are a partnership or corporation, filing without an EIN will result in rejected returns and penalties. The IRS may also assess penalties for failure to obtain an EIN when required.

If you are unsure whether you need one, the safest approach is to request one. There is no downside to having an EIN you do not use, and the process is free and takes minutes. If you have already been operating without one and believe you should have one, contact the IRS or speak with a tax professional about correcting your filings.

Frequently Asked Questions

Can I get an EIN if I do not have a Social Security number?

Yes. You can use an ITIN (Individual Taxpayer Identification Number) instead. You will need to explore for an ITIN first through the IRS, then use it to request your EIN. This process takes longer than explore with a Social Security number.

How long does it take to receive an EIN?

Online applications are processed when ready and you receive your number right away. Mail applications take about four weeks. Fax requests are processed within four business days. Phone applications are completed during the call.

Can I change my EIN if I change my business name?

No. Your EIN stays the same for the life of your business, even if you change your business name, address, or structure. You do not need a new one unless you start a completely separate business.

What if I lose my EIN or forget it?

You can look it up on old tax returns, bank statements, or correspondence from the IRS. You can also call the IRS at 1-800-829-4933 and provide your business information to retrieve it. The IRS can also issue you a new EIN letter if you need official documentation.

Do I need an EIN if I am just starting a business and have not made any money yet?

If you plan to have employees or operate as a partnership or corporation, you need an EIN before you hire anyone or file your first tax return. If you are a sole proprietor with no employees, you can wait until you have income to report, but many people get one early to open a business bank account.