What Is an EIN Number and How to Get One?

To get an Employer Identification Number, apply directly through the IRS — it’s free, takes a few minutes online, and the number is issued at the end of the session. An EIN is the nine-digit number (XX-XXXXXXX) the IRS assigns to businesses, trusts, and estates for tax filing, and it functions like a Social Security number for the entity. Third-party websites will charge up to $300 to file the same application the IRS provides at no cost.¹ Once assigned, the number stays with the entity permanently.

Do You Actually Need One

Corporations, partnerships, and multi-member LLCs need an EIN whether or not they have employees, because the IRS treats them as separate taxpayers from their owners.² Non-profits and trusts that file their own returns also need one.

Sole proprietors can use their Social Security number until they hire an employee or become liable for excise taxes; either event triggers the requirement.²

Single-member LLCs are the common gray area. If you have no employees and no excise tax liability, the IRS doesn’t require an EIN for federal tax purposes and you can use your SSN. But many banks won’t open a business account without one, and some states require an EIN for state tax registration, so most single-member LLCs end up getting one anyway.³

Estates that generate income after the decedent’s death need their own EIN, applied for by the personal representative.²

What to Have Ready Before You Start

The IRS uses Form SS-4 for every EIN application. The online version won’t let you save and return, so gather everything first.⁴

You’ll need:

The entity’s legal name exactly as it appears on the organizing documents, plus any trade or DBA name.
A responsible party — the individual who controls or manages the entity. Except for government entities, this has to be a real person, not another business, and that person supplies a Social Security number or ITIN. Foreign applicants with neither can enter “N/A” on that line.⁵
A physical mailing address.
The reason for applying (starting a new business, hiring employees, changing entity structure, and so on).
An estimate of how many employees you expect in the next 12 months. This affects filing frequency: employers with $1,000 or less in annual Social Security, Medicare, and withheld income tax can file Form 944 annually instead of Form 941 quarterly.⁶

One limit worth knowing before you start: the IRS issues only one EIN per responsible party per day, no matter which method you use. If you need numbers for several entities, spread the applications across separate days.⁵

How to Apply

Online (Fastest)

The IRS online application issues your EIN immediately at the end of the session. It runs Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern Time (next day), Saturday 6:00 a.m. to 9:00 p.m. ET, and Sunday 6:00 p.m. to midnight ET.⁷

Complete it in one sitting. Close the browser or let the session time out, and you start over.

Fax

Fax a completed Form SS-4 to the IRS service center and you’ll typically receive your EIN within four business days.⁵

Mail

Mailing Form SS-4 takes roughly four to five weeks. Use this route only if you have no faster option.⁵

Phone (International Applicants Only)

Applicants outside the U.S. who can’t use the online tool call 267-941-1099, Monday through Friday, 6:00 a.m. to 11:00 p.m. ET. An agent walks through the SS-4 questions and assigns the number on the call.¹

Having Someone Else File

If your accountant or attorney is doing the paperwork, Form SS-4 has a third-party designee section. Sign Line 18 to authorize that person to answer IRS questions about the form and receive the assigned number. Their authority ends the moment the EIN is issued, and the confirmation notice is mailed to you, not to them.⁵

When the Online Application Won’t Go Through

A few things trip up the online system even when your information is correct.

The most common is a name-and-SSN mismatch for the responsible party. If the IRS database stores a slightly different version of the name — a missing middle initial, a hyphenated last name recorded differently — the system rejects the application. Try the exact name format printed on the Social Security card.

Reference Number 101 means another entity is already on file with the same name as yours. When that happens, the online tool won’t finish the application; you’ll need to file Form SS-4 by fax or mail, which adds processing time.

One more thing to know once you have the number: you can use it right away for most purposes, including opening a bank account, but the IRS says it can take up to two weeks for a new EIN to register in the Taxpayer Identification Number Matching Program. During that window, an automated verification attempt may fail even though the number is valid.¹

If You Misplace the Number Later

An EIN is never lost from the IRS’s records; it’s permanently assigned. Check old tax returns or the original bank account paperwork first. If it’s nowhere to be found, call the IRS business and specialty tax line and ask for Letter 147C, which officially confirms your existing EIN.¹

1
Internal Revenue Service. Employer Identification Number
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eCFR. 26 CFR 301.6109-1 – Identifying Numbers
3
Internal Revenue Service. Single Member Limited Liability Companies
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Internal Revenue Service. About Form SS-4, Application for Employer Identification Number (EIN)
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Internal Revenue Service. Instructions for Form SS-4 (12/2025)
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Internal Revenue Service. About Form 944, Employer’s Annual Federal Tax Return
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Internal Revenue Service. Get an Employer Identification Number