Form SS-4: How to Apply for an EIN (2026 Guide)

If you’re starting a U.S. business, including as a foreign founder, Form SS-4 is how you get your Employer Identification Number (EIN). Form SS-4 is the IRS application for an EIN, the 9-digit number the IRS uses to identify your business for tax filing and reporting.

This guide covers who needs to file, how to apply online, by fax, by mail, or by phone, and how to complete the form line by line. It also explains what to do once your EIN confirmation letter arrives.

Key Takeaways

• Form SS-4 is the IRS application for an EIN, and the IRS issues EINs free of charge.
• Online applications get an EIN immediately, fax generally takes about 4 business days, and mail takes about 4 weeks.
• Foreign founders without an SSN or ITIN can’t apply online. They must fax or mail Form SS-4, or call the IRS if the business has no U.S. principal place of business.

Form SS-4 Explained: The IRS Application for an EIN

Form SS-4, Application for Employer Identification Number, collects the details the IRS uses to open your business tax account. Once it’s processed, the IRS assigns a 9-digit EIN in the format 12-3456789.

Who Needs to File Form SS-4

You generally need an EIN if your business has employees, pays employment or excise taxes, or withholds tax on non-wage income paid to a nonresident alien. You also need one to operate a partnership, LLC, corporation, tax-exempt organization, estate, most trusts, or a retirement plan.

This includes foreign-owned U.S. LLCs. A foreign-owned single-member LLC needs an EIN to file Form 5472 when it has reportable transactions with its foreign owner, even if it has no employees.

Pro Tip: Cleer Tax supports preparation and filing of Form SS-4 for foreign founders, so you can have your EIN before you open a U.S. bank account or file your first return. Contact us to get started.

When You Don’t Need an EIN

A sole proprietor with no employees and no excise or employment tax returns may use their SSN instead. Certain grantor trusts also don’t need a separate EIN.

You also don’t need a new EIN to change your business name, address, or responsible party. Report those changes on Form 8822-B instead, and report a new responsible party within 60 days. A business that loses its EIN shouldn’t file another SS-4.

When to Apply

Form your LLC or corporation with the state first, then apply for an EIN. If you file Form SS-4 before the entity exists, the IRS may delay your application. If you’re still choosing a state, see our guide to Delaware incorporation.

There’s no filing deadline for Form SS-4, but you can’t open a business bank account, hire employees, or file returns without an EIN. You can use a new EIN right away for most needs. Allow up to 2 weeks before you e-file a return or make electronic tax deposits.

How to Apply for an EIN: Online, Fax, or Mail

The IRS recommends applying online when you’re eligible, and international applicants can also apply by phone. Use only one method per entity so you don’t end up with two EINs.

Applying Online

Online is the fastest route, and the IRS issues your EIN as soon as the application is approved. You can use it only if all of these are true: your entity was formed in the U.S., its principal place of business is in the U.S., and the responsible party has an SSN or ITIN.

1. Form your LLC or corporation with the state.
2. Open the IRS online EIN application during its operating hours. As of October 2026, those are Monday to Friday 6 a.m. to 1 a.m., Saturday 6 a.m. to 9 p.m., and Sunday 6 p.m. to midnight Eastern. Hours change often, so check IRS.gov before you start.
3. Complete the application in one session. You can’t save your progress, and the session times out after 15 minutes of inactivity.
4. Download and save your EIN confirmation notice at the end of the session.

The IRS issues only one EIN per responsible party per day, regardless of the method you use.

Applying by Fax

Under the IRS Fax-TIN program, you’ll generally receive your EIN within 4 business days. Fax-TIN accepts applications 24 hours a day, 7 days a week.

1. Complete and sign Form SS-4.
2. Include a return fax number so the IRS can fax your EIN back.
3. Fax the form to 855-641-6935 if your principal place of business is in the 50 states or DC.
4. If it isn’t, fax 855-215-1627 from within the U.S. or 304-707-9471 from outside the U.S.

Applying by Mail

Mail is the slowest method, and the IRS mails your EIN in about 4 weeks. The IRS suggests sending the form at least 4 to 5 weeks before you need the number.

1. Complete, sign, and date Form SS-4.
2. If your principal place of business is in the 50 states or DC, mail it to Internal Revenue Service, Attn: EIN Operation, Cincinnati, OH 45999.
3. If it isn’t, mail it to Internal Revenue Service, Attn: EIN International Operation, Cincinnati, OH 45999.
4. To check on a mailed application, call the IRS at 800-829-4933.

Applying Without an SSN or ITIN (Foreign Founders)

If the responsible party has no SSN or ITIN, you can’t use the online application. Enter “foreign” on line 7b and apply by fax or mail.

Which fax number or address you use depends on where the business is located, not on the founder’s citizenship. If the business has no U.S. principal place of business, you can also call 267-941-1099 (not toll-free), Monday to Friday, 6 a.m. to 11 p.m. Eastern. The caller must be authorized to receive the EIN and answer questions about the form.

Foreign applicants may have any duly authorized person sign Form SS-4. For the wider picture, see our tax guide for foreign founders.

How to Fill Out Form SS-4, Line by Line

Form SS-4 is one page, but small errors on it can delay your EIN or set up the wrong tax profile. The IRS asks you to enter “N/A” on lines that don’t apply, except where an entry is required.

Information to Gather Before You Start

Have these details ready before you open the form or the online application:

1. The entity’s legal name, exactly as it appears on your formation documents
2. Any trade name (DBA) you’ll use
3. Mailing address and physical street address, if different
4. County and state, or country, where the business is located
5. Responsible party’s full name and SSN or ITIN, if they have one
6. Number of LLC members, if the entity is an LLC
7. Entity type and any planned tax election
8. Reason for applying and the date the business started
9. Closing month of your accounting year
10. Highest number of employees expected in the next 12 months
11. A specific description of your main business activity

Lines 1–7: Entity Name, Address, and Responsible Party

On line 1, enter the legal name exactly as it appears on your charter or formation document, including any suffix like Inc. or Corp. Line 2 is for a trade name only if it differs from the legal name.

Lines 4a–4b are the mailing address the IRS will use for correspondence. Lines 5a–5b are the physical address, only if it differs, and it can’t be a P.O. box. For foreign addresses, include the city, province or state, postal code, and the full country name.

Lines 7a–7b name the responsible party, the individual who ultimately owns or controls the entity. Unless the applicant is a government entity, this must be a person, not a company. Enter their SSN or ITIN on line 7b, or “foreign” if they don’t have one and aren’t eligible for one.

Lines 8–9: LLC Details and Entity Type

Line 8a asks whether the applicant is an LLC. If yes, enter the number of members on line 8b and answer line 8c, which asks whether the LLC was organized in the U.S.

On line 9a, check the box that best describes the entity. Checking a box here is not a tax classification election. Elections are made separately on Form 8832 or Form 2553.

Lines 10–18: Reason for Applying, Business Activity, and Employees

Check only one box on line 10. A foreign-owned single-member LLC that needs an EIN to file Form 5472 should check “Other” and enter “Foreign-owned U.S. disregarded entity filing Form 5472.”

• Line 11: The date the business started. Foreign applicants enter the date they began business in the U.S.
• Line 12: The closing month of your accounting year, usually December.
• Lines 13–15: Expected employees (enter 0 if none), whether you’ll file Form 944, and the first date wages were paid, or N/A.
• Line 16: One box for your principal activity.
• Line 17: A specific description of your main line of business. “General contractor for residential buildings” works; “consulting” alone may not.
• Line 18: Whether the entity has ever received an EIN.

The third-party designee section is optional. If the designee’s address or phone number matches yours, you must apply by fax or mail.

Completing Form SS-4 for an LLC

How you fill out line 9a depends on how many members the LLC has and how it will be taxed.

• Single-member LLC, U.S. owner: Check “Other” and write “disregarded entity.”
• Single-member LLC, foreign owner filing Form 5472: Check “Other” and write “Foreign-owned U.S. disregarded entity-Form 5472.”
• Multi-member LLC: Check “Partnership.”
• LLC electing corporate tax treatment: Check “Corporation” only if you’ll file Form 8832 or Form 2553, and write the return you’ll file (Form 1120 or 1120-S). A single-member LLC also writes “Single-member.”

Not sure whether corporate treatment fits? Our guide to C Corp taxes covers the trade-offs.

Common Form SS-4 Mistakes to Avoid

Most SS-4 problems come from a handful of avoidable errors. Each one below may delay your EIN or create a tax profile you’ll have to correct later.

Using a Name That Doesn’t Match Your Formation Documents

A name that differs from your state filing, even by a missing suffix, can cause delays or a mismatch with your bank. Copy the legal name exactly from your certificate of formation or articles of incorporation. Online, the IRS accepts only letters, numbers, hyphens, and ampersands, so spell out other symbols.

Choosing the Wrong Entity Type

Checking “Corporation” for an LLC that hasn’t elected corporate treatment tells the IRS to expect a corporate return. Match line 9a to your actual classification, and check “Corporation” only if you’ll file Form 8832 or Form 2553.

Leaving Out LLC Member Details

Skipping lines 8a–8c, or entering the wrong member count, can lead the IRS to assume the wrong default classification. Answer every LLC line and make the member count match your operating agreement.

Listing the Wrong Responsible Party

The responsible party must be an individual who owns or controls the entity, not another company or a formation service. The IRS states that nominees aren’t authorized to apply for an EIN. List the actual owner or controlling officer.

Using a Registered Agent’s Address

If you list your registered agent’s address as your mailing address, IRS notices may go to the agent instead of you. Use an address where you’ll actually receive mail, and file Form 8822-B if it changes.

Describing the Business Too Vaguely

A line 17 entry like “business” or “services” doesn’t tell the IRS what you do. Describe your main activity specifically, such as “software development for retail companies.”

Applying for a Second EIN You Don’t Need

Submitting through more than one method, or reapplying after losing your number, can create duplicate EINs. Use one method per entity. If you’ve lost your EIN, call the Business and Specialty Tax Line at 800-829-4933 instead of filing again.

Leaving the Signature Blank

The IRS may return an unsigned fax or mail application, and a third-party designee authorization isn’t valid without a signature. Have an authorized person sign and date the form before you send it.

Your EIN Confirmation Letter (CP 575 and 147C)

Your EIN confirmation letter is the document banks and payment processors ask for as proof of your EIN. The IRS issues a CP 575 notice when it assigns your number, and Letter 147C if you need confirmation later.

CP 575: Your Original EIN Notice

If you apply online, you can view, print, and save your EIN notice at the end of the session. Applicants who fax or mail receive it from the IRS. Keep it in your permanent records, since the IRS can’t reissue the original CP 575.

If you’re eligible for an IRS Business Tax Account, you can download a digital CP 575 there. The IRS says banks and other institutions accept it as written confirmation of your EIN.

Letter 147C: Confirming an Existing EIN

If you’ve lost your CP 575 and can’t use a Business Tax Account, request Letter 147C, EIN Previously Assigned. Call the Business and Specialty Tax Line at 800-829-4933, Monday to Friday, 7 a.m. to 7 p.m. local time. The IRS will verify your identity before releasing the information.

How Cleer Tax Can Help With Your EIN Application

If you’re a foreign founder without an SSN or ITIN, you can’t use the IRS online application. That means faxing or mailing Form SS-4, getting the routing right, and waiting days or weeks with no room for errors.

Cleer Tax supports preparation and filing of Form SS-4 for foreign founders and U.S. businesses. Our team reviews your entity details, responsible party information, and LLC classification before the form goes to the IRS.

We also provide guidance on what comes next, including Form 5472 and your first tax return for a foreign-owned company.

Clients remain responsible for providing accurate and timely information and making required tax payments.

Contact us to get your EIN application started.

Frequently Asked Questions (FAQ)

These are the questions founders most often search for about Form SS-4.

What is an SS-4 form?

Form SS-4 is the IRS Application for Employer Identification Number. Businesses, trusts, estates, and other entities file it to get a 9-digit EIN for tax filing and reporting.

How do I get a copy of my SS-4 letter?

The IRS can’t reissue your original CP 575 notice. If eligible, download a digital CP 575 from your IRS Business Tax Account, or call 800-829-4933 to request Letter 147C.

Where do I mail Form SS-4?

If your principal place of business is in the U.S., mail it to Internal Revenue Service, Attn: EIN Operation, Cincinnati, OH 45999. Otherwise, use Attn: EIN International Operation at the same city and ZIP code.

What is the IRS fax number for an EIN application?

Domestic applicants fax 855-641-6935. Applicants with no U.S. principal place of business fax 855-215-1627 from within the U.S. or 304-707-9471 from outside the U.S. Include a return fax number.

Can I submit Form SS-4 online?

Yes, if your entity was formed in the U.S., its principal place of business is in the U.S., and the responsible party has an SSN or ITIN. The IRS issues the EIN immediately once approved.

Does it cost anything to apply for an EIN?

No. The IRS issues EINs free of charge, regardless of the method you use. Any fee you pay a third party covers their preparation service, not the EIN itself.

Can a company help me file Form SS-4?

Yes. Cleer Tax supports preparation and filing of Form SS-4, especially for foreign founders who must fax or mail. Contact us to get started.

Disclaimer: This article is for general informational purposes only and does not constitute tax, legal, or accounting advice. IRS procedures, fax numbers, and operating hours may change, and how the rules apply depends on your specific facts. Consult a qualified tax professional before acting on this information.