A Federal Tax ID is a nine-digit number the IRS assigns to identify a business or other entity for tax purposes

A Federal Tax ID, also called an Employer Identification Number (EIN), works like a Social Security number but for a business, nonprofit, partnership, or trust. The IRS uses it to track tax filings, payroll, and other business records. If you run any kind of business—even a sole proprietorship—you may need one, though the rules differ depending on your structure and whether you have employees.

The number itself is formatted as XX-XXXXXXX (two digits, a hyphen, then five digits). It is issued free by the IRS and does not expire. Once assigned, it stays with that entity for life, even if the business closes or changes ownership.

Key Takeaways

  • A Federal Tax ID is a nine-digit number issued by the IRS to identify a business, nonprofit, partnership, or trust for tax purposes.
  • Sole proprietors without employees can use their Social Security number instead, but many choose to get an EIN to keep business and personal finances separate.
  • You must have a Federal Tax ID if you have employees, operate as a partnership or corporation, or run certain types of businesses like farms or rental properties.
  • You can obtain a Federal Tax ID online through the IRS website, by mail, fax, or phone, and the process is free and usually takes minutes to hours.

Who needs a Federal Tax ID

The IRS requires a Federal Tax ID if your business has any employees—even one part-time worker. You also need one if you operate as a partnership, S corporation, C corporation, LLC with multiple members, or nonprofit organization. Trusts, estates, and certain investment accounts also need one.

If you are a sole proprietor with no employees, you can file taxes under your Social Security number instead. However, many sole proprietors still get a Federal Tax ID to keep business and personal finances separate, to protect their Social Security number from exposure, and because some banks and vendors require one before opening a business account.

Specific business types that always need a Federal Tax ID include farms, rental properties held as a business (not just a personal investment), and any business that withholds taxes from employee paychecks or pays certain contractors.

How to obtain a Federal Tax ID

The fastest way is online through the IRS website at irs.gov. Go to the EIN Assistant tool, answer questions about your business structure and location, and you receive your number when ready. You will need your Social Security number or ITIN, the business start date, and the state where the business is located.

If you cannot explore online, you can mail Form SS-4 to the IRS, fax it, or call the IRS Business and Specialty Tax Line at 1-800-829-4933. By mail, processing takes about four weeks. By fax or phone, you typically receive your number the same day or within a few business days. There is no cost for any method.

You will need to provide basic information: your name, the business name and address, the type of business structure, the reason you are requesting an EIN (hiring employees, opening a bank account, and so on), and the date the business began or will begin operations.

What a Federal Tax ID is used for

The IRS uses your Federal Tax ID to match tax returns, payroll filings, and other documents to your business. When you hire employees, you use it to file payroll tax returns and report wages on W-2 forms. If you operate as a corporation or partnership, you file your business income tax return under this number.

Banks and credit card companies use it to open business accounts and issue business credit cards. State and local governments may require it for business licenses, sales tax permits, and unemployment insurance accounts. Vendors and contractors sometimes ask for it before doing business with you.

If your business closes, you do not need to cancel the Federal Tax ID—it straightforward becomes inactive. The IRS keeps the record on file.

Federal Tax ID versus Social Security number for business

A sole proprietor can legally use a Social Security number on business tax returns and bank accounts. The difference is privacy and separation. When you use your Social Security number for business, your personal and business finances are linked in IRS records and with financial institutions. A Federal Tax ID creates a separate identity for the business.

Using a Federal Tax ID also protects your Social Security number from being shared with vendors, contractors, and other third parties who might ask for a tax ID. If you plan to hire employees or grow the business, you will need a Federal Tax ID anyway, so getting one early simplifies the transition.

Federal Tax ID for different business structures

The requirement and process vary slightly by how you structure your business. A sole proprietor can choose to use either a Social Security number or a Federal Tax ID. A partnership must have a Federal Tax ID. An LLC with one member can use the owner's Social Security number unless it elects to be taxed as a corporation, in which case it needs a Federal Tax ID.

An S corporation or C corporation must have a Federal Tax ID. A nonprofit organization must have one. A trust or estate typically needs one if it has income or if it will hire someone. If you are unsure whether your structure requires one, the IRS EIN Assistant tool walks you through the decision based on your answers.

What happens after you receive a Federal Tax ID

Once you have your number, write it down and keep it in a safe place. You will need it to open a business bank account, file tax returns, hire employees, and explore for business licenses and permits. The IRS will send you a confirmation letter by mail if you applied by phone, fax, or mail; if you applied online, you can print your confirmation when ready.

Do not share your Federal Tax ID publicly or with people who do not have a legitimate business reason to see it. Treat it as you would a Social Security number. If your business structure changes—for example, you convert from a sole proprietorship to an LLC—you may need a new Federal Tax ID, though the IRS can advise you on this when the change happens.

Frequently Asked Questions

Can I get a Federal Tax ID if I have not started my business yet?

Yes. When you explore, you provide the date the business will begin operations. The IRS issues the number before that date so you can open a bank account and make other preparations. You do not need to be actively operating to receive one.

Do I need a Federal Tax ID if I am a freelancer or independent contractor?

Not required if you have no employees and file as a sole proprietor—you can use your Social Security number. However, many freelancers get one to keep business and personal finances separate and to avoid sharing their Social Security number with clients.

What if I lose my Federal Tax ID number?

You do not need to request a new one. The IRS has your number on file permanently. If you forget it, you can look it up on old tax returns, bank statements, or business licenses. You can also contact the IRS at 1-800-829-4933 to confirm your number.

Can one person have more than one Federal Tax ID?

Yes, if you operate multiple separate businesses. Each business entity gets its own Federal Tax ID. However, if you operate multiple businesses under one legal entity, you use one Federal Tax ID for all of them.

How long does it take to get a Federal Tax ID?

Online applications are processed when ready and you receive your number right away. Phone and fax applications typically take the same day or one to two business days. Mail applications take about four weeks. There is no cost regardless of method.