What a Tax ID Number Is and Who Needs One
A Tax ID Number (also called an Employer Identification Number or EIN) is a nine-digit identifier the IRS assigns to businesses, nonprofits, trusts, and certain individuals. It works like a Social Security number does for people, but for tax purposes tied to a business entity rather than a person.
You need a Tax ID Number if you operate a business as a sole proprietor with employees, run a partnership, own an LLC or corporation, manage a nonprofit, or control a trust or estate. If you are a sole proprietor with no employees, you can use your Social Security number instead — but many sole proprietors get a Tax ID anyway to keep business and personal finances separate.
The IRS does not charge for a Tax ID Number. The application itself is free, and there is no annual fee to maintain one.
Key Takeaways
- You can obtain a Tax ID Number for free by applying to the IRS using Form SS-4, either online, by mail, fax, or phone.
- Online applications through the IRS website are processed immediately and give you your number the same day.
- By mail or fax, the IRS typically issues your number within four business days; by phone, you receive it during the call.
- You will need your Social Security number or Individual Taxpayer Identification Number, your business name and address, and information about the business structure and ownership.
- Once issued, a Tax ID Number does not expire and remains valid for the life of the business unless you formally close it.
How to Apply Online (Fastest Method)
The online application through the IRS website is the fastest way to get a Tax ID Number. You go to the IRS's online EIN application portal, answer questions about your business, and receive your number immediately upon submission. The entire process takes 10 to 15 minutes.
To apply online, you need a valid Social Security number or ITIN, your business name and address, the business owner's name and address, and information about your business structure (sole proprietorship, partnership, LLC, S corporation, C corporation, nonprofit, trust, or estate). You also need to know the principal business activity — the IRS provides a list of codes to choose from, or you can describe what your business does and they will code it for you.
After you submit, the IRS displays your Tax ID Number on the screen. Write it down immediately. The IRS will also email you a confirmation, though the number is valid the moment it appears on screen.
Applying by Mail or Fax
If you cannot apply online, you can submit Form SS-4 by mail or fax. Download the form from the IRS website (irs.gov), fill it out, and send it to the IRS fax number or mailing address listed on the form itself — the address varies by state.
By fax, the IRS typically processes your application within four business days. By mail, allow two to three weeks. You will receive a letter in the mail with your Tax ID Number and a copy of your completed Form SS-4.
Form SS-4 asks for the same information as the online application: your name and Social Security number, business name and address, business structure, and principal business activity. Print clearly or type the form. If you are mailing it, keep a copy for your records.
Applying by Phone
You can also call the IRS Business and Specialty Tax Line at 1-800-829-4933 to apply by phone. You will speak with an IRS representative who will ask you the same questions as the online form, and they will issue your Tax ID Number during the call. Write down the number they give you.
Phone lines are typically open Monday through Friday, 7 a.m. to 7 p.m. your local time. Wait times vary, especially during tax season (January through April). Have your information ready before you call so the conversation moves quickly.
Documents and Information You Will Need
| Information Needed | What It Means |
|---|---|
| Your Social Security number or ITIN | The IRS uses this to verify your identity and link the Tax ID to you personally. |
| Business name | The legal name of your business as it appears on your business license or formation documents. |
| Business address | The physical location where your business operates. A home address is acceptable for home-based businesses. |
| Business structure | Whether you operate as a sole proprietorship, partnership, LLC, S corp, C corp, nonprofit, trust, or estate. |
| Principal business activity | A description of what your business does. The IRS provides a code list, or you can describe it in your own words. |
| Ownership information | The name and address of the owner or owners. For partnerships and LLCs, you may need to list all members. |
You do not need to bring original documents to the IRS. They verify your identity using the information you provide. If you are applying in person (which is rare and only available at certain IRS offices), bring a photo ID and your Social Security card or ITIN letter.
What Happens After You Receive Your Tax ID Number
Once you have your Tax ID Number, use it on all business tax forms, bank accounts, and vendor accounts. If you have employees, you will use it to file payroll taxes and report wages. If you operate a nonprofit, you will use it on your Form 990 annual return and to maintain your tax-exempt status.
Keep your Tax ID Number in a safe place. You will need it for the life of your business. The number does not expire unless you formally dissolve the business and notify the IRS. If your business closes, you can file a final tax return and request that the IRS deactivate the number, though this is optional.
If you lose your Tax ID Number, you can look it up on the IRS website or call the Business and Specialty Tax Line. You do not need to apply for a new one.
Frequently Asked Questions
How long does it take to get a Tax ID Number?
Online applications are processed immediately — you receive your number on screen the same day. Phone applications give you the number during the call. By fax, allow four business days. By mail, allow two to three weeks. Processing times may be longer during tax season.
Can I use my Social Security number instead of getting a Tax ID Number?
If you are a sole proprietor with no employees, yes — you can use your Social Security number on your tax return. However, many sole proprietors get a Tax ID anyway to keep business and personal finances separate and to protect their Social Security number from being shared with vendors and banks.
Do I need a Tax ID Number before I start my business?
Not always. If you are a sole proprietor with no employees, you can start operating and use your Social Security number. You only need a Tax ID if you hire employees, form an LLC or corporation, or want to keep your business finances separate. Get one before you open a business bank account if you plan to use a Tax ID.
What if I applied and never received my Tax ID Number?
If you applied online or by phone, you should have received it immediately. If you applied by mail or fax and it has been longer than the stated processing time, call the IRS Business and Specialty Tax Line at 1-800-829-4933 to check the status. Have your Social Security number and business name ready.
Can I change my Tax ID Number if I change my business name?
No. Your Tax ID Number stays the same even if you change your business name. You simply notify the IRS of the name change on your next tax return or by filing Form 8822-B. You do not need a new Tax ID Number.