What Is a Business Tax ID Number? How to Apply for and Find an EIN

A business tax ID number is the Employer Identification Number (EIN), a nine-digit number the IRS assigns to your business for tax reporting. It functions like a Social Security Number for your company, letting the IRS track your business’s tax obligations separately from your personal finances. Applying is free, and if you apply online the IRS issues the number immediately when you finish the form.¹

The number takes the format 00-0000000 and stays with your business as a permanent record of its interactions with the IRS.² Most states also issue their own tax identification numbers for sales tax, unemployment insurance, and state withholding, but those are separate from your federal EIN.

Who Needs an EIN

You need an EIN if your business does any of the following:

Hires employees and puts them on payroll.
Files employment, excise, or alcohol, tobacco, and firearms tax returns, even with no employees.
Withholds income tax on non-wage payments to a non-resident alien.

You also need an EIN, regardless of whether you have employees, if you operate as a partnership, corporation, limited liability company (LLC), tax-exempt organization, estate, trust (except certain grantor-owned revocable trusts), retirement plan or IRA including Keogh plans, real estate mortgage investment conduit, or farmers’ cooperative.³

Sole Proprietors Without Employees

A sole proprietor with no employees and none of the triggers above is not legally required to get an EIN and can use their Social Security Number on business tax filings instead.² Many still choose to get one. Every W-9 sent to a client or vendor would otherwise carry the owner’s SSN, and using an EIN on those forms substantially reduces exposure to identity theft. You can also request an EIN purely for banking or state tax purposes.³

What to Have Ready Before You Apply

Gather this information before you start:

The legal name of the entity exactly as it appears on your formation documents, plus any trade name or DBA.
The name and SSN or ITIN of the responsible party, meaning the individual who controls or manages the entity and its assets. This must be a person, not another business; the only exception is government entities. Someone who merely owns or benefits from the entity without control, such as a minor beneficiary of a trust, does not qualify.⁴
Your physical street address and mailing address.
The entity type: corporation, partnership, LLC, sole proprietor, trust, estate, or another category on the form.
The reason for applying, such as starting a new business, hiring employees, creating a trust, or setting up a pension plan.

How to Apply

Applying is free directly through the IRS. Watch out for third-party sites that charge a fee for what the IRS provides at no cost.¹ There are three methods.

Online

The online application is the fastest route. You answer the questions, review your entries, and get your EIN the moment you finish. Availability is limited to these Eastern Time hours:

Monday through Friday: 6:00 a.m. to 1:00 a.m. the next day.
Saturday: 6:00 a.m. to 9:00 p.m.
Sunday: 6:00 p.m. to midnight.

To qualify for the online tool, your principal place of business must be in the United States and the responsible party must have a valid SSN, ITIN, or EIN. You can apply for only one EIN per responsible party per day.³

Fax

Complete Form SS-4 and fax it to the IRS with a return fax number included. You will typically receive your EIN within four business days.³

Mail

You can also mail a completed Form SS-4 to Internal Revenue Service, Attn: EIN Operation, Cincinnati, OH 45999. Allow four to five weeks for processing.⁵ Whichever method you use, the IRS mails a confirmation notice (CP 575) to the address on your application. Keep it. Banks, payroll providers, and some agencies may ask for it as proof.

If a Name Mismatch Blocks You

The most frequent online rejection is a mismatch between the responsible party’s name and SSN and what the IRS and Social Security Administration have on file, even when your own records look correct.⁶ After a name change through marriage or a court order, confirm the Social Security Administration has updated its records before applying. If the online tool keeps rejecting you, fax or mail is a reliable backup.

Applying From Outside the United States

If your principal place of business is outside the United States, the online application is not available to you. International applicants can call 267-941-1099 (not toll-free) Monday through Friday, 6:00 a.m. to 11:00 p.m. Eastern Time, with a completed Form SS-4 in hand; fax the form to 304-707-9471 for a response within four business days; or mail it to Internal Revenue Service, Attn: EIN International Operation, Cincinnati, OH 45999, allowing about four weeks. If the responsible party has no SSN or ITIN and is not eligible for one, enter “foreign” or “N/A” on line 7b of Form SS-4.⁵

When You Need a New EIN

You do not need a new EIN when your business changes its name, moves, or sees an ownership shift that leaves the entity intact. Structural changes are different:⁷

A sole proprietor who incorporates or forms a partnership needs a new EIN.
A partnership needs a new EIN if it incorporates, dissolves and starts a new partnership, or one partner takes over as a sole proprietor.
A corporation needs a new EIN if it receives a new charter from the secretary of state, merges and creates a new corporation, or converts to a partnership or sole proprietorship. A corporation that survives a merger keeps its existing EIN.
An LLC needs a new EIN if it terminates and reforms as a corporation or partnership.

Finding a Lost EIN

Check old IRS notices, prior tax returns, and bank account records first, because your EIN appears on all of them. If none of those work, 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 (Alaska and Hawaii use Pacific Time). The IRS will verify your identity and give the number over the phone if you are authorized to receive it. You can also request Letter 147C, which confirms your previously assigned EIN in writing, or pull an entity transcript through the IRS business transcript service.³

Keeping Your Information Current

When the responsible party changes, whether through a new owner or a different officer stepping in, file Form 8822-B within 60 days. The same form updates your business address.⁸ Skipping this update can leave the IRS unable to verify authorized contacts, which can delay future filings and make it harder to recover the EIN later.

Cost of Not Having One When Required

Filing an information return with a missing or incorrect taxpayer identification number carries a penalty of $250 per return, capped at $3,000,000 per calendar year.⁹ Correct the error within 30 days of the filing deadline and the penalty drops to $50 per return; correct it after 30 days but before August 1 and it is $100 per return. Intentional disregard raises the penalty to at least $500 per return with no annual cap.

The practical costs show up sooner. Without an EIN, you generally cannot open a business bank account, run payroll, or apply for many business licenses, so operations can stall before revenue starts.

1
Internal Revenue Service. Get an Employer Identification Number
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eCFR. 26 CFR 301.6109-1 – Identifying Numbers
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Internal Revenue Service. Employer Identification Number
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Internal Revenue Service. Responsible Parties and Nominees
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Internal Revenue Service. Instructions for Form SS-4
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Taxpayer Advocate Service. When Taxpayers Struggle to Obtain an EIN, Everyone Loses
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Internal Revenue Service. When to Get a New EIN
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Internal Revenue Service. Form 8822-B, Change of Address or Responsible Party
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Office of the Law Revision Counsel. 26 USC 6721 – Failure to File Correct Information Returns