EIN and Tax ID: What's the Difference and When You Need Each One

EIN and Tax ID are not the same thing, though the terms are often used interchangeably

An EIN (Employer Identification Number) is a nine-digit number the IRS assigns to businesses, nonprofits, trusts, and certain other entities. A Tax ID is a broader category that includes several different identification numbers — EIN is one type of Tax ID, but so are Social Security Numbers (SSN) and Individual Taxpayer Identification Numbers (ITIN). The confusion happens because people sometimes say "Tax ID" when they mean "EIN," but they are not identical terms.

The practical difference matters when you are filling out forms or talking to a bank or vendor. If a form asks for your "Tax ID," you may need to provide an SSN, ITIN, or EIN depending on what you are — a sole proprietor, a business entity, or a non-citizen resident. If a form specifically asks for an "EIN," you must have one; an SSN will not work in that box.

Key Takeaways

EIN is one type of Tax ID; Tax ID is the umbrella term that includes EIN, SSN, and ITIN.
Sole proprietors without employees often use their Social Security Number as their Tax ID instead of obtaining an EIN.
Businesses with employees, partnerships, corporations, and nonprofits must have an EIN and cannot use an SSN in its place.
The IRS form you file determines which number you need — some forms require an EIN specifically, while others accept an SSN.

When you need an EIN instead of just a Tax ID

You must obtain an EIN if you operate as a partnership, S-corporation, C-corporation, LLC with multiple members, nonprofit organization, or trust. You also need an EIN if you are a sole proprietor with employees on your payroll. The IRS will not let you file payroll taxes or certain other business forms using only your Social Security Number in these situations.

If you are a sole proprietor with no employees and no payroll, you can use your Social Security Number as your Tax ID on most tax forms. However, many sole proprietors obtain an EIN anyway for privacy reasons — it keeps your SSN off business documents, bank accounts, and vendor records. This is optional but common practice.

How Tax ID and EIN appear on different IRS forms

Form 1040 (individual income tax return) asks for your "Identification Number," which is your Social Security Number. Form 1120 (corporate tax return) requires an EIN. Form 1065 (partnership return) requires an EIN. Form 990 (nonprofit return) requires an EIN. The form itself tells you which number to use — read the instructions for the specific form you are filing.

When you open a business bank account, the bank will ask whether you have an EIN or will provide your SSN. If you are a sole proprietor without employees, you can give your SSN. If you are any other business structure, you must provide an EIN. The bank will not accept an SSN for a business entity that is not a sole proprietorship.

What documents show your Tax ID or EIN

Your Social Security Number appears on your Social Security card and on IRS documents like your tax return transcripts. Your EIN appears on IRS Form SS-4 (the form you submit to request an EIN), on IRS Form 147-C (the confirmation letter the IRS mails after you receive your EIN), and on all business tax returns you file using that number.

If you have lost your EIN confirmation letter, you can call the IRS Business and Specialty Tax Line at 1-800-829-4933 to request a new copy. You can also look up your EIN on the IRS website if you filed a return using that number — the EIN will appear on the return itself. Keep your confirmation letter in a safe place; you will need the EIN number many times over the life of your business.

How to request an EIN if you need one

You request an EIN by submitting IRS Form SS-4 (process for Employer Identification Number). You can file this form online through the IRS website, by mail, by fax, or by phone. The online method is fastest — you receive your EIN when ready after you submit the form and can use it right away. By mail or fax, the IRS typically mails your confirmation letter within two to three weeks.

To complete Form SS-4, you will need your Social Security Number, the legal name of your business, your business address, and information about what your business does. If you are forming a corporation or LLC, you will also need your state business registration number (sometimes called your state ID number or charter number). Have these details ready before you start the form.

Tax ID requirements when you hire employees

The moment you hire your first employee, you must have an EIN — you cannot use your Social Security Number for payroll taxes. This is true even if you are a sole proprietor. Before you run your first payroll, you must obtain an EIN and register with your state's labor department and unemployment insurance program. The EIN is the number the IRS uses to track all your payroll tax deposits and filings.

If you are a sole proprietor who has been using your SSN and then hire an employee, obtain your EIN before you pay that person. Once you have the EIN, use it on all future business documents, bank accounts, and tax forms — do not switch back and forth between your SSN and EIN. Mixing numbers on your tax filings creates confusion with the IRS and can delay processing.

Common mistakes when reporting Tax ID or EIN

The most common error is writing the wrong number on a tax form. Double-check that you have copied your EIN or SSN correctly — a single digit wrong will cause the IRS to mismatch your return to your account. Another frequent mistake is using an SSN on a form that requires an EIN, or vice versa. Read the form instructions to confirm which number goes in which box.

A third mistake is obtaining an EIN but then continuing to use your SSN on business documents and tax forms. Once you have an EIN, use it consistently on all business filings, bank accounts, and vendor forms. Switching between numbers makes it harder for the IRS to track your business income and can trigger correspondence asking you to clarify which number is correct.

Frequently Asked Questions

Can I use my Social Security Number as my Tax ID if I own a business?

Yes, if you are a sole proprietor with no employees. You can use your SSN as your Tax ID on your business tax return. However, if you hire employees, form a partnership, create an LLC with multiple members, or incorporate, you must obtain an EIN and cannot use your SSN.

What is the difference between an EIN and a Federal Tax ID?

An EIN is a Federal Tax ID. The terms are used interchangeably. Both refer to the nine-digit number the IRS assigns to a business entity. "Tax ID" is sometimes used more broadly to include SSN and ITIN as well, but "Federal Tax ID" and "EIN" mean the same thing.

Do I need an EIN if I am a sole proprietor with no employees?

No, you do not need an EIN. You can use your Social Security Number as your Tax ID on your tax return. Many sole proprietors obtain an EIN anyway for privacy — it keeps your SSN off business bank accounts and vendor records — but it is not required by law unless you have employees.

How long does it take to receive an EIN?

If you file Form SS-4 online, you receive your EIN when ready. If you file by mail or fax, the IRS typically mails your confirmation letter within two to three weeks. You can use your EIN as soon as you receive it, even if you have not yet received the physical confirmation letter.

What if I filed a tax return with the wrong Tax ID number?

Contact the IRS as soon as you notice the error. For business returns, call the Business and Specialty Tax Line at 1-800-829-4933. For individual returns, call 1-800-829-1040. Have your return and the correct number ready. The IRS can correct the number in their system and prevent delays in processing your return or issuing a refund.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.