Fax Form SS-4 to Get an EIN: Numbers, Fields, and Wait Times

To fax Form SS-4 to the IRS from within the 50 states or D.C., send it to 855-641-6935; the IRS typically faxes an Employer Identification Number back within four business days, as long as you included a return fax number on the application.¹ International applicants use a different number depending on where they’re faxing from. The number is the easy part. Getting the form filled in cleanly so the IRS doesn’t bounce it is where applications stall.

IRS Fax Numbers for Form SS-4

The right fax number depends on where the business, or the individual applicant, is located.

Principal place of business in one of the 50 states or the District of Columbia: fax to 855-641-6935.
No principal place of business in the U.S., faxing from inside the U.S.: fax to 855-215-1627.
No principal place of business in the U.S., faxing from outside the U.S.: fax to 304-707-9471.¹

These numbers can change. Verify the current number on IRS.gov or in the latest Form SS-4 instructions before you send.

Should You Be Faxing at All?

For most domestic applicants, the IRS online EIN tool is faster because it issues the number immediately on approval. Faxing is the right channel when the online tool won’t work for you: the responsible party has no SSN or ITIN, the business’s principal place of business is outside the United States (the online tool is unavailable to foreign applicants), or you’re applying outside the online tool’s operating hours and want a paper trail.² Mail is the slowest route at roughly four weeks, so if the online tool isn’t an option, fax is your best bet.³

Fill Out SS-4 So It Doesn’t Get Rejected

An incomplete or inconsistent SS-4 either gets rejected outright or sits while the IRS tries to sort it out. A few fields cause most of the trouble.

Legal Name and Entity Type

The legal name on Line 1 must match your formation documents exactly, including suffixes like “Inc.” or “LLC.” A mismatch between what your state has on file and what you write on the SS-4 is one of the fastest ways to trigger a rejection.³ The entity type you select on Line 9a has to match your legal structure. Checking “LLC” when you filed as an S-corp creates downstream problems with your tax filings that are harder to fix than getting the box right the first time.

Responsible Party

The responsible party on Lines 7a–7b is the individual who owns or controls the entity and manages its funds. With a narrow exception for government entities, it must be an actual person, not another business.⁴ Enter that person’s SSN or ITIN on Line 7b. If the responsible party is a foreign individual who doesn’t have and can’t get either number, write “foreign” or “N/A.” Sole proprietors enter their own SSN or ITIN unless they’re nonresident aliens with no effectively connected U.S. income. For estates, enter the deceased person’s SSN or ITIN.³

The Two Address Fields

Form SS-4 has two address sections and they follow different rules. The mailing address on Lines 4a–4b can be a P.O. box. The physical address on Lines 5a–5b, which is your principal place of business, cannot.³

Lines People Skip

Line 10 (reason for applying) is required and does not accept “N/A.” Check exactly one box. Line 16 (principal activity) also requires a selection, and Line 17 needs a written description of your business. The IRS won’t issue an EIN if these are blank.⁵

Signature

The form must be signed by the right person: the individual for a sole proprietorship, a principal officer for a corporation, an authorized member or officer for a partnership or other organization, or the fiduciary for a trust or estate. Foreign applicants can have any authorized person sign. An unsigned form won’t be processed.⁵

Sending the Fax

Use a traditional fax machine or an online fax service that lets you upload the completed PDF. Either works.

If any part of the form is handwritten, use dark ink and write clearly. Fax transmission reduces image quality, and a smudged SSN or illegible business name is enough to set your application aside. Include a cover sheet with your name, a contact phone number, and the return fax number where the IRS should send your EIN. Without a return fax number, you lose the four-business-day turnaround and will likely wait for the mailed notice instead.

Save the transmission confirmation report. That’s your proof the fax went through if the IRS later says they never received it. Evenings and weekends may help you avoid busy signals on the IRS line, though there’s no guarantee.

What Comes Back, and When

Under the IRS Fax-TIN program, you can expect your EIN by fax within four business days, provided you supplied a return fax number.³

Separately, the IRS mails a formal confirmation letter called CP 575 to the business address on your form. It usually arrives several weeks after the EIN is assigned and is the official record of your number. Keep it somewhere safe. Banks, creditors, and state agencies sometimes ask for the CP 575 as proof of the EIN, and the IRS only issues the original once.

If Your EIN Doesn’t Arrive

If more than a week has gone by since you faxed and nothing has come back, call the IRS Business and Specialty Tax Line at 800-829-4933. It’s open Monday through Friday, 7:00 a.m. to 7:00 p.m. local time (Alaska and Hawaii follow Pacific). A representative can verify your identity and either read the EIN over the phone or fax a verification letter known as a 147C letter.⁶

If a return or deposit is due before your EIN arrives, don’t substitute your personal SSN. Write “Applied For” and the date you submitted the application in the space where the EIN would go. For tax deposits, mail payment to the IRS service center for your filing area, payable to “United States Treasury,” and include your name as shown on the SS-4, your address, the type of tax, the period covered, and the date you applied.³

1
Internal Revenue Service. Where to File Your Taxes for Form SS-4
2
Internal Revenue Service. Get an Employer Identification Number
3
Internal Revenue Service. Instructions for Form SS-4 (12/2025)
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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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Internal Revenue Service. Telephone Assistance Contacts for Business Customers