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 number the IRS uses to identify your business for tax purposes. The IRS issues it free, and you need one if you have employees, operate as a partnership or corporation, or file certain business tax returns.
If you are a sole proprietor with no employees, you may use your Social Security Number instead — but many sole proprietors get an EIN anyway to keep their personal and business finances separate. Once you have an EIN, it stays with your business for life, even if you change the business structure or location.
Key Takeaways
- You can get an EIN free from the IRS online at irs.gov/ein, by phone, by mail, or by fax, and the online method gives you a number the same day.
- You will need your Social Security Number, the business legal name, business address, and the date you started or plan to start the business.
- The IRS does not mail an EIN certificate; instead, you print a confirmation letter from your online account or receive one by mail if you applied by phone or mail.
- If you already have an EIN and need to verify it or update business information, you can look it up through the IRS or contact them directly.
Getting an EIN Online (Same-Day Number)
The fastest way to get an EIN is through the IRS website at irs.gov/ein. You fill out Form SS-4 online, and the IRS issues your number immediately. You can then print a confirmation letter right away or save it to your account.
To apply online, you need a valid Social Security Number or Individual Taxpayer Identification Number (ITIN), the business legal name, the business mailing address, and the date the business started or will start. You also need to know your business structure (sole proprietor, partnership, S corporation, C corporation, LLC, nonprofit, and so on). The online application takes about 15 minutes.
Online applications are available Monday through Friday, 7 a.m. to 10 p.m. Eastern Time. If you apply outside those hours, you can still submit the form, but you will not receive your number until the next business day during those hours.
Getting an EIN by Phone, Mail, or Fax
If you cannot apply online, you can call the IRS Business and Specialty Tax Line at 1-800-829-4933. Have Form SS-4 filled out before you call. The IRS representative will ask you the questions on the form, issue your EIN over the phone, and mail you a confirmation letter within two weeks.
You can also mail a completed Form SS-4 to the IRS address listed on the form itself — the address depends on your state. Processing by mail takes about four weeks. Some states also allow you to fax Form SS-4 to a specific fax number; check the form for your state's fax line.
If you are applying by phone, mail, or fax, have your Social Security Number, business name, business address, and business start date ready. The IRS will not issue a number on the phone if you cannot provide these details.
What Documents You Need Before You Apply
You do not need to gather many documents to get an EIN — the IRS does not ask for proof of business registration, a lease, or a business license. However, you do need to know certain information about yourself and your business before you start the application.
| Information Needed | What It Means |
|---|---|
| Your Social Security Number or ITIN | The IRS uses this to link the EIN to you personally. If you are not a U.S. citizen, an ITIN works instead. |
| Business legal name | The official name your business is registered under, not a nickname or "doing business as" name (though you can list that separately). |
| Business mailing address | A physical address where the IRS can reach you. A P.O. box alone is not enough; you need a street address. |
| Business start date | The date you started the business or plan to start it. If you have not started yet, use the date you expect to begin operations. |
| Business structure | Whether you are a sole proprietor, partnership, LLC, S corporation, C corporation, nonprofit, or other type. |
If you are applying on behalf of someone else (for example, as a tax professional or accountant), you will also need to provide your name and relationship to the business owner.
How Long It Takes and What You Receive
If you apply online, you receive your EIN the same day. The IRS displays it on your screen and lets you print a confirmation letter immediately. You can use the number right away for hiring, opening a business bank account, or filing taxes.
If you apply by phone, you get the number during the call and receive a written confirmation letter by mail within two weeks. If you apply by mail or fax, expect four weeks for processing. During that time, you can call the IRS at 1-800-829-4933 to ask if your application has been received and processed.
The IRS does not mail a formal "EIN certificate." Your confirmation letter serves as proof that you have an EIN. Keep this letter in your records. If you lose it, you can print another one from your IRS online account or request a new one by calling the IRS.
Using Your EIN After You Receive It
Once you have an EIN, use it on all business tax forms, business bank account applications, and payroll documents. If you have employees, you must use your EIN on W-2 forms and payroll tax returns. If you are a sole proprietor with no employees, you may still use your EIN on business returns instead of your Social Security Number for privacy.
You do not need to re-apply for an EIN if you change your business location, change your business name, or change your business structure — though you do need to notify the IRS of these changes. You can update your business information through your IRS online account or by calling 1-800-829-4933.
If your business closes, you do not need to cancel the EIN. Simply stop using it and note the closure date on your final tax return. The IRS will deactivate it automatically.
Frequently Asked Questions
Do I need an EIN if I am a sole proprietor with no employees?
No, you can use your Social Security Number on your tax return instead. However, many sole proprietors get an EIN anyway to keep their personal and business finances separate and to protect their Social Security Number from being shared with vendors and clients.
Can I get an EIN if my business has not started yet?
Yes. On the application, enter the date you plan to start the business. The IRS will issue an EIN even if you have not yet hired employees or opened a bank account. You can use it as soon as you receive it.
What if I already have an EIN and cannot find it?
Call the IRS at 1-800-829-4933 with your Social Security Number and business name, and they will look up your EIN for you. You can also check your old tax returns or business bank statements — the EIN is usually listed there.
How much does it cost to get an EIN?
Nothing. The IRS issues EINs free. If a website or service charges you to get an EIN, that is a scam. Go directly to irs.gov/ein or call 1-800-829-4933.
Can I get an EIN for a business I do not own yet?
No. You must be the owner or an authorized representative of the business. If you are applying on behalf of someone else, you need their permission and your relationship to the business documented.