What Is a Federal Employer Identification Number?

A Federal Employer Identification Number, usually shortened to EIN, is a nine-digit number the IRS assigns to businesses, nonprofits, trusts, estates, and other entities to identify them for tax purposes. It works like a Social Security number for the entity. The IRS writes it in a two-plus-seven format (XX-XXXXXXX), issues it free of charge, and never charges a renewal fee because the number is permanent.¹

Once assigned, an EIN stays with that entity for its entire existence. Even if you close the business, the IRS cannot cancel the number or reassign it to anyone else. The number keeps your business’s tax activity separate from your personal finances, which matters for filing returns, running payroll, and opening bank accounts.

Who Needs a Federal Employer Identification Number

If your business has employees, you need an EIN to report and pay employment taxes. That’s true whether you run a corporation, partnership, LLC, or sole proprietorship. Employees are not the only trigger, though. You also need an EIN to operate any of the following, even without payroll:

Corporations
Partnerships
Limited liability companies (LLCs)
Tax-exempt organizations
Estates and trusts, except certain revocable trusts owned entirely by the grantor

You also need one if you withhold taxes on income paid to a nonresident alien, or if you file excise or alcohol, tobacco, and firearms tax returns.¹

Sole Proprietors Without Employees

Sole proprietors sit in a different spot. If you have no employees, no Keogh retirement plan, and no excise tax obligations, you can use your personal Social Security number for tax purposes and skip the EIN. Many sole proprietors still get one so they don’t have to hand out their Social Security number to clients and vendors, but the IRS does not require it in that situation.¹

How to Apply for an EIN

You apply on IRS Form SS-4. The IRS charges nothing regardless of how you submit it, and it offers several ways to file.²

Online

The fastest option. If your principal place of business is in the United States or a U.S. territory, and you have the responsible party’s Social Security number or Individual Taxpayer Identification Number, you can apply through the IRS website and receive your EIN immediately upon approval.²

Fax

Under the IRS Fax-TIN program, you fax a completed Form SS-4 and generally get your EIN back by fax within four business days.³

Mail

You can also mail Form SS-4. Plan ahead: the IRS recommends submitting by mail at least four to five weeks before you’ll actually need the number.³

Phone (International Applicants)

If your principal place of business is outside the United States, the online tool is not available. Call 267-941-1099 (not toll-free) between 6:00 a.m. and 11:00 p.m. Eastern time, Monday through Friday, with a completed Form SS-4 in front of you. The representative will assign an EIN over the phone. If asked, you must mail or fax the signed form within 24 hours.⁴

One Per Day, and No Fees

The IRS limits issuance to one EIN per responsible party per day across all methods. If you need numbers for several entities, space out the applications.²

The IRS is direct on the cost: “You never have to pay a fee for an EIN.” Third-party websites charge anywhere from $50 to $300 to submit the same free form. Unless an accountant or attorney is handling it as part of broader business formation work, there’s no reason to pay.²

What You Use an EIN For

Once you have the number, it shows up in almost every official interaction your business has with the government and financial institutions.

Opening a business bank account. Banks require an EIN, or a Social Security number for sole proprietors, to open a business account.⁵
Hiring employees. Your EIN goes on every payroll filing, W-2, and employment tax return.
Filing federal and state tax returns, which use the EIN to match filings to the right account.
Applying for business licenses and permits. State and local agencies often ask for an EIN during licensing.⁶
Applying for business credit. Lenders use the EIN to pull business credit reports.

All 1099 filers are required to have an EIN, and it must appear on every information return you file.⁷

When You Need a New EIN

Your EIN belongs to a specific entity structure. Fundamentally change the structure, and the old EIN no longer applies. Renaming the business or moving to a new address never triggers a new EIN on its own. The IRS lists the triggers by entity type:⁸

Sole proprietors need a new EIN when they incorporate, form a partnership, or declare bankruptcy.
Corporations need a new EIN when they receive a new charter from the secretary of state, change to a partnership or sole proprietorship, or merge into a new corporation. A subsidiary also gets its own EIN.
Partnerships need a new EIN when they incorporate, when one partner takes over as a sole proprietor, or when they dissolve and start a new partnership. An ownership change that doesn’t terminate the partnership does not require a new EIN.
LLCs need a new EIN when they terminate and form a new corporation or partnership, or when a single-member LLC begins filing excise or employment tax returns.
Trusts need a new EIN when a revocable trust becomes irrevocable, a living trust converts to a testamentary trust, or a living trust terminates by distributing property to a residual trust.

The pattern holds across entity types: structural changes that create a legally different entity require a new EIN, while administrative changes like renaming or relocating do not.⁸

Finding a Lost EIN

Losing track of an EIN is more common than you’d expect, especially for older businesses. Places to look:

The CP 575 notice the IRS mailed when it first assigned the EIN. That’s the most direct record.
Any federal tax return your business has filed. The EIN appears prominently on each one.
Tax notices and other IRS correspondence.
The bank where you opened your business account.

If none of those turn up the number, call the IRS Business and Specialty Tax Line at 800-829-4933, Monday through Friday, 7:00 a.m. to 7:00 p.m. your local time. You’ll need to verify your identity before a representative can share account information.⁹

For publicly traded companies, EINs appear on SEC filings and can be found through the SEC’s EDGAR database.¹⁰

If You No Longer Need the EIN

The IRS cannot cancel or reissue an EIN, but it can deactivate the account so no future filings are expected. Before asking for deactivation, file all outstanding tax returns and pay any balance owed. Then send a letter that includes the entity’s EIN, legal name, address, the original EIN assignment notice if you still have it, and the reason for deactivation. Mail it to one of these addresses:¹¹

Internal Revenue Service, MS 6055, Kansas City, MO 64108
Internal Revenue Service, MS 6273, Ogden, UT 84201

Tax-exempt organizations use the Ogden address (Attn: EO Entity, Mail Stop 6273) and can also fax the letter to 855-214-7520.¹¹

1
Internal Revenue Service. Employer Identification Number
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Internal Revenue Service. Get an Employer Identification Number
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Internal Revenue Service. Instructions for Form SS-4 (Rev. December 2025)
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Internal Revenue Service. Instructions for Form SS-4
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U.S. Small Business Administration. Open a Business Bank Account
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U.S. Small Business Administration. Get Federal and State Tax ID Numbers
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Internal Revenue Service. Publication 1099 General Instructions for Certain Information Returns
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Internal Revenue Service. When to Get a New EIN
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Internal Revenue Service. Telephone Assistance Contacts for Business Customers
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U.S. Securities and Exchange Commission. EDGAR Full Text Search
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Internal Revenue Service. If You No Longer Need Your EIN