A Tax ID is a nine-digit number the IRS uses to identify you for tax purposes

A Tax ID (also called an Employer Identification Number or EIN) is a unique nine-digit number assigned by the Internal Revenue Service. It works like a Social Security number, but for tax and business purposes instead of personal identification. The IRS uses it to track income, file returns, and manage tax accounts.

You may need a Tax ID if you are self-employed, run a business, hire employees, or operate as a partnership or corporation. Some people also need one to open a business bank account, apply for business credit, or report certain types of income. The number itself is free and does not cost anything to obtain.

A Tax ID is different from a Social Security number. You can use your Social Security number for sole proprietorship taxes if you work alone and have no employees. But once you hire staff or form a business structure like an LLC or corporation, the IRS requires a separate Tax ID.

Key Takeaways

  • A Tax ID is a nine-digit number issued by the IRS to identify businesses and self-employed people for tax purposes.
  • You need a Tax ID if you hire employees, form a business entity (LLC, corporation, partnership), or operate as a self-employed person with a business name.
  • Getting a Tax ID is free and can be done online through the IRS website, by mail, fax, or phone — the online method is fastest.
  • Once you have a Tax ID, you use it on tax returns, W-2 forms, business bank accounts, and any official business paperwork the IRS requires.

Who needs to get a Tax ID

You need a Tax ID if you operate a business in any form. This includes sole proprietors who hire even one employee, partnerships, limited liability companies (LLCs), S corporations, and C corporations. If you are self-employed and work alone under your own name with no employees, you can use your Social Security number instead — but many self-employed people get a Tax ID anyway for privacy and business separation.

You also need a Tax ID if you are a nonprofit organization, a trust, an estate, or a business that files certain tax forms with the IRS. Some people need one to open a business bank account, even before they officially start operating. Banks often require a Tax ID before they will issue a business checking account.

If you are unsure whether you need one, the IRS has a worksheet on their website that walks through your situation. The worksheet asks about your business structure and whether you have employees, and it tells you whether a Tax ID is required.

How to get a Tax ID from the IRS

The fastest way to get a Tax ID is online through the IRS website at irs.gov. You fill out Form SS-4 (Application for an Employer Identification Number) on the IRS interactive tool. The process takes about 15 minutes, and you receive your Tax ID immediately after you submit. You can print a confirmation page with your number right away.

If you cannot use the online tool, you can apply by mail, fax, or phone. Mail takes two to four weeks. Fax takes one to two weeks. Phone applications are handled by the IRS during business hours, and you get your number the same day. To apply by phone, call the IRS at 1-800-829-4933.

You will need basic information to apply: your legal business name, the address where the business operates, the type of business structure (sole proprietor, LLC, corporation, etc.), and the reason you need the Tax ID. If you are hiring employees, have the expected date you will hire them. You do not need to have already hired anyone — you can apply before your first employee starts.

What information you provide when applying

Form SS-4 asks for your name, the business name, the business address, and your Social Security number or individual Tax ID. You will also state what type of business you operate (manufacturing, retail, services, etc.) and your business structure (sole proprietor, partnership, LLC, corporation). The form asks when your business started or will start, and whether you expect to have employees.

If you are applying on behalf of a business you do not own — for example, if you are a manager or accountant handling the paperwork — you provide your name and title, and the owner's name and Social Security number. The IRS needs to know who actually owns the business.

You do not need tax returns, financial statements, or proof of business registration to apply. The IRS issues the Tax ID based on the information you provide on the form. Some states require you to register your business separately, but that is a state requirement, not an IRS one.

What you use a Tax ID for after you receive it

Once you have a Tax ID, you use it on your business tax return (Form 1040-C for sole proprietors, Form 1065 for partnerships, Form 1120 for corporations, etc.). You also use it on W-2 forms when you pay employees, on 1099 forms when you pay contractors, and on business bank accounts and credit applications.

Your Tax ID appears on any official correspondence from the IRS about your business. If you hire employees, you use it to register for payroll taxes and unemployment insurance. You also use it when you apply for business licenses, permits, or loans.

Keep your Tax ID number in a safe place. You will need it every year for tax filing, and you may need it when you apply for business credit or insurance. Unlike a Social Security number, a Tax ID is not sensitive personal information — you can share it with employees, contractors, and vendors without risk.

Tax ID versus Social Security number for self-employed people

If you are self-employed and work alone with no employees, you can file taxes using your Social Security number. Many sole proprietors do this and never get a Tax ID. However, some self-employed people get a Tax ID anyway because it separates their personal and business finances, and it keeps their Social Security number off business documents.

Once you hire an employee, you must have a Tax ID — the IRS does not allow you to use your Social Security number for payroll. If you think you might hire someone in the future, getting a Tax ID early can save you the step later.

A Tax ID also makes it easier to open a business bank account and build business credit separately from your personal credit. Some banks will not open a business account without a Tax ID, even for a sole proprietor.

What happens after you receive your Tax ID

After the IRS issues your Tax ID, you do not have to renew it or reapply. The number stays with your business for as long as the business exists. If you close the business, you stop using the Tax ID, but you do not have to formally cancel it with the IRS.

If you change your business structure — for example, if you convert from a sole proprietorship to an LLC — you may need a new Tax ID. The IRS treats different business structures as separate entities. You should contact a tax professional or the IRS to confirm whether you need a new number for your new structure.

If you lose your Tax ID number, you can look it up on the IRS website or call the IRS at 1-800-829-4933. You do not have to reapply for a new one.

Frequently Asked Questions

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

Yes, if you are self-employed and have no employees, you can use your Social Security number on your tax return. However, once you hire even one employee, you must have a Tax ID. Many self-employed people get a Tax ID anyway to keep their personal and business finances separate.

How long does it take to get a Tax ID?

Online applications are processed immediately — you receive your number the same day. Mail takes two to four weeks. Fax takes one to two weeks. Phone applications are handled during business hours, and you get your number the same day you call.

Do I need a Tax ID before I start my business?

You can apply for a Tax ID before your business officially opens. You provide the expected start date on the form. Many people get a Tax ID before they hire employees or open a business bank account, even if the business has not yet generated income.

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

You can look up your Tax ID on the IRS website using your business name and address, or you can call the IRS at 1-800-829-4933. You do not have to reapply — the number stays the same.

Do I need a Tax ID if I sell things online or on a marketplace?

If you operate as a sole proprietor selling on platforms like eBay or Etsy and have no employees, you can use your Social Security number. However, if you register as a business entity or hire help, you need a Tax ID. Check your state's rules — some states require a Tax ID for any online sales activity.