How to Apply for a Federal Identification Number

To apply for a Federal Identification Number, officially the Employer Identification Number (EIN), submit IRS Form SS-4 through the online EIN Assistant at irs.gov, by fax, by mail, or by phone if you’re an international applicant. The online tool is fastest and issues the number immediately. The application is free directly from the IRS, and it takes about 15 minutes if you have your information ready.¹

Do You Actually Need One

Corporations, partnerships, LLCs, tax-exempt organizations, estates, trusts, and retirement plans all need an EIN.¹ You also need one if you hire employees, withhold taxes on payments to non-resident aliens, or file excise tax returns. A sole proprietor with no employees can file under a Social Security Number and skip the EIN, but many still get one so banks will open a business checking account and so the SSN stays off invoices and contracts.

What to Have Ready Before You Start

The online application cannot be saved partway through, so pull everything together first. You’ll need:

The entity’s full legal name exactly as it appears on your formation documents.
Your entity type: sole proprietorship, partnership, corporation, LLC, estate, trust, or another structure.
The reason for applying, such as starting a new business, hiring employees, opening a bank account, or changing organizational structure.
The responsible party’s name and taxpayer ID.
The entity’s physical address, plus a mailing address if it’s different.
The date the business started or was acquired.
A description of your principal business activity.
The number of employees you expect to hire in the next 12 months, including zero if none.²

Naming the Responsible Party

Every EIN application has to name a responsible party, and that person must be an individual, not another business entity. Government agencies are the only exception.³ The responsible party is the person who owns or controls the entity and manages its funds. For a corporation, that’s typically the principal officer; for a partnership, a general partner; for a trust, the grantor; for an estate, the executor. You’ll provide that person’s Social Security Number or ITIN on the form.⁴ If more than one person could qualify, list the one you want the IRS to treat as the primary contact.

The Four Ways to Apply

Online

If your principal place of business or legal residence is in the United States or a U.S. territory, use the online EIN Assistant at irs.gov. A valid application returns the EIN on the spot.¹ The tool is available Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern, Saturday from 6:00 a.m. to 9:00 p.m. Eastern, and Sunday from 6:00 p.m. to midnight Eastern.⁵

One catch. The session times out after 15 minutes of inactivity, with no way to save and resume, so an expired session means starting over.⁶ With your information ready, that’s a non-issue.

Fax

Complete Form SS-4 and fax it to 855-641-6935 if you’re a domestic applicant.⁷ Include a return fax number and the IRS will typically fax back your EIN within four business days.¹ International applicants use 855-215-1627 from within the U.S. or 304-707-9471 from outside the country.

Mail

Mail your completed Form SS-4 to Internal Revenue Service, Attn: EIN Operation, Cincinnati, OH 45999.⁷ Processing takes about four weeks, so plan ahead.² International applicants mail to the same Cincinnati address but use “Attn: EIN International Operation.”

Phone, International Applicants Only

If your principal place of business is outside the United States, call 267-941-1099, Monday through Friday, 6:00 a.m. to 11:00 p.m. Eastern.¹ An IRS representative walks through the Form SS-4 questions and assigns the EIN during the call. It is not a toll-free number.

Having Someone Else Apply for You

To let an accountant, attorney, or other person handle the application, complete the third-party designee section on Form SS-4 (Line 18) and sign the form.⁸ The designee’s authority ends the moment the EIN is assigned. If the designee’s address or phone number matches the taxpayer’s, the application must go in by mail or fax rather than online or by phone.

The Application Is Free

Getting an EIN from the IRS costs nothing, no matter which method you use.⁵ That matters because a set of deceptive websites charges up to $300 to file the same free application on your behalf. The FTC has warned that these sites copy IRS logos, colors, and formatting, put “IRS” in their domain names, and label their tools “EIN Assistant,” which is the actual name of the IRS’s free tool. They often bury fees in fine print and don’t disclose that they aren’t affiliated with the government.⁹

Go directly to irs.gov. If a site asks for your credit card during an EIN application, it isn’t the IRS.

What Happens After You Apply

You can use your EIN for most purposes right away: give it to your bank, put it on invoices, and file paper tax returns. There’s a roughly two-week delay before the number fully propagates through IRS electronic systems, though. During that window you won’t be able to e-file a return, make electronic tax payments, or pass the IRS Taxpayer Identification Number Matching Program.¹ If you’re setting up payroll or need to e-file, build that lag into your timeline.

The IRS mails a CP 575 confirmation notice to the address on your application. Keep it. If you ever lose it, call the IRS Business and Specialty Tax Line at 800-829-4933 (Monday through Friday, 7:00 a.m. to 7:00 p.m. local time) and ask for Letter 147C, which verifies your previously assigned EIN.¹

If the Application Gets Rejected or Stuck

The IRS limits each responsible party to one EIN per day, regardless of method.¹ Setting up multiple entities? Spread the applications across consecutive days.

The most common cause of online rejections is a mismatch between the responsible party’s name and their SSN or ITIN. Check that the name matches Social Security Administration records exactly, including hyphens, suffixes, and middle names. If the online tool keeps rejecting the entry, submit Form SS-4 by fax or mail, where a human reviewer can sort out the discrepancy.

Business name conflicts can also send an application to manual review. If the IRS flags your entity name as too similar to an existing one, you may be prompted to submit by fax or mail instead. The same goes for technical issues or server problems; waiting 24 hours and trying again usually clears temporary glitches.

For anything you can’t resolve on your own, call the IRS Business and Specialty Tax Line at 800-829-4933, Monday through Friday, 7:00 a.m. to 7:00 p.m. local time.¹⁰ Have your Form SS-4 information in front of you when you call.

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Internal Revenue Service. Employer Identification Number
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IRS. Instructions for Form SS-4 (Rev. December 2025)
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Internal Revenue Service. Responsible Parties and Nominees
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Internal Revenue Service. Form SS-4 – Application for Employer Identification Number
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Internal Revenue Service. Get an Employer Identification Number
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Taxpayer Advocate Service. When Taxpayers Struggle to Obtain an EIN, Everyone Loses
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Internal Revenue Service. Where to File Your Taxes for Form SS-4
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Internal Revenue Service. Instructions for Form SS-4
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Federal Trade Commission. FTC Warns Operators of Websites that Charge for an Employer Identification Number and Claim Affiliation with the IRS
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Internal Revenue Service. Telephone Assistance Contacts for Business Customers