How to Fill Out Form SS-4 and Apply for an EIN by Fax
Mircea RilăCheck the completed SS-4 and eligibility before filing.
This is a walkthrough of filling in Form SS-4 and applying for an EIN by fax. When the form is signed, send it to the IRS SS-4 fax number for where you live and operate, and confirm the official filing chart before you transmit.
Forming a United States entity, such as a Delaware or Wyoming LLC, is straightforward for international entrepreneurs. However, opening a US business bank account (like Mercury, Relay, or Brex), processing customer payments via Stripe, and establishing vendor relationships requires an Employer Identification Number (EIN) issued by the Internal Revenue Service (IRS).
Use the IRS fax numbers directory to distinguish EIN applications from other form submissions.
If you do not possess a US Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN), you cannot use the instant IRS online application portal. For international founders, submitting Form SS-4 by fax to the IRS Fax-TIN unit is the primary official path.
This guide outlines how to complete Form SS-4 and how to receive your official IRS confirmation letter.
Numbers checked 8 October 2026: use the official IRS instructions for this form. Fax numbers can change without notice. Sending starts at $0.99 for up to 10 document pages, with $0 on failed delivery. A card authorization may remain pending until your bank releases it.
Prefer guided filing? Fax your EIN application to the IRS with guided filing for $19.99. The service helps prepare and transmit your packet; IRS acceptance and processing are separate from successful fax delivery.
Send the signed Form SS-4
After the form is complete, fax it to the right number for your location. See the current IRS SS-4 fax numbers.
Use the IRS Where to File Form SS-4 chart. Routing follows the legal residence or principal business location and, for international applicants, where the fax is sent from. A US incorporation certificate alone does not select the domestic number. Include a working return fax number if you want a fax response.
Why You Must Apply by Fax: The SSN/ITIN Constraint
The IRS operates an instant online EIN tool, but it enforces a strict gateway restriction: the individual listed as the "Responsible Party" must enter a valid 9-digit US SSN or ITIN.
| Applying route | When to use it |
|---|---|
| IRS online application | Applicant and responsible party meet the IRS eligibility requirements |
| Signed SS-4 by fax | Online application is unavailable or unsuitable; select the correct routing number |
| Signed SS-4 by mail | Fax is unavailable; allow time for postal delivery and processing |
Use the current SS-4 instructions for every field. Line 18 asks about an EIN previously requested; the return fax number belongs in the applicant's fax-number field by the signature area.
Line 1: Legal Name of Entity
Enter the exact name of your business as registered with your state's Secretary of State (e.g., "Acme Software Solutions LLC"). Do not abbreviate or alter punctuation.
Line 4a: 4b: Mailing Address
Enter the address where you want to receive tax notices. This can be your US registered agent address, a US virtual mailbox, or your international business address.
Line 5a: 5b: Physical Address
If your business has a physical address different from the mailing address, enter it here. For international founders without a physical US office, this can be your operational headquarters abroad.
Line 7a: Name of Responsible Party
Enter the full legal name of the individual who controls, manages, or directs the entity (typically the founder or managing member). The IRS requires this to be an individual human being, not another holding company.
Line 7b: SSN, ITIN, or EIN
If the responsible party has no SSN or ITIN and is ineligible to obtain one, the instructions allow “foreign” or “N/A” on line 7b. An entry is required. Do not use that exception merely because an eligible person has not yet applied for an ITIN.
Line 8a: 8c: Limited Liability Company (LLC) Information
- Line 8a: Check "Yes" if your entity is an LLC.
- Line 8b: Enter the number of LLC members (owners). If you are the sole owner, enter
1. - Line 8c: If line 8a is Yes, indicate whether the LLC was organized in the United States.
Line 9a: Type of Entity
- For a domestic single-member LLC using its default classification, follow the disregarded-entity instructions. When requesting an EIN for Form 5472, the IRS specifies “Foreign-owned U.S. disregarded entity-Form 5472” on line 9a. An entity electing corporate treatment follows different instructions.
- If you are a multi-member LLC, check "Partnership".
- If you formed a US Corporation, check "Corporation" and specify the form number (e.g., "1120").
Line 10: Reason for Applying
Check the appropriate box. Most international founders check "Started new business" and specify the core business activity (e.g., "SaaS software development and digital subscriptions").
Line 18: Have You Ever Applied for an EIN Before?
Check "No" unless this specific entity previously received an EIN.
Signature Block
Have the appropriate authorized person sign and date the form. The instructions identify the permitted signer for each entity type; international applicants may use a duly authorized person.
- Print your name clearly.
- Provide a valid contact phone number with country code.
- Include your return fax number: The IRS requires a return fax number to transmit your EIN confirmation notice back to you.
How the IRS Delivers Your EIN
Include a working return fax number in the applicant's fax-number field so the IRS can fax the assigned EIN back. Keep the number active through processing and retain the returned document and assignment notice.
A 147C letter confirms an EIN previously assigned; it is not the initial assignment notice. The IRS also provides an EIN verification notice through eligible Business Tax Accounts. See its CP575 notice guidance.
CP 575, CP 575A–J and Letter 147C
- CP575A–J is the original notice series that assigns a new EIN. The IRS says the original cannot be duplicated or recreated, so keep it with your permanent records.
- Digital CP575 confirms your EIN and is available only through Business Tax Account. The IRS says banks and other institutions accept it as written confirmation of an entity's EIN, and that it can substitute for the original CP575A–J notice and for Letter 147C.
- Letter 147C, EIN Previously Assigned, is the other way to confirm an EIN you already have.
- Changing your mailing or location address or the responsible party uses Form 8822-B. The IRS says responsible-party changes must be reported within 60 days.
Source: IRS. Understanding your CP575 notice, checked 14 October 2026.
Applied online and got stopped instead? See EIN reference number 101 for what the message means and how to fax Form SS-4.
Choose a receiving number that will last
A free 24-hour number is useful for an immediate reply, but usually too short for an SS-4 application. A 30-day number for $4.99 gives more time. Check the live IRS processing estimate and keep the line active until the response arrives. The guided EIN service includes its own 90-day return line.
If a reply has not arrived, check the processing-status page and follow the IRS contact instructions. Do not immediately send a duplicate SS-4 application for an entity that may already have an EIN.
Comparison: Filing Options and Pricing
When choosing how to obtain your EIN by fax, you have three primary approaches:
| Method | Pricing | What Is Included | Trade-offs |
|---|---|---|---|
| DIY Manual Fax (via standard SingleFax send) | $0.99 (≤10 pages) | Direct transmission to IRS Fax-TIN unit with proof of delivery | You must fill the PDF manually and arrange your own received fax line to receive the IRS response |
| Direct IRS application | No IRS application fee | Apply through an eligible IRS method | You prepare the form and manage the reply yourself |
| SingleFax EIN by Fax | $19.99 | Guided SS-4 wizard, automated IRS faxing, 90-day dedicated return number, email delivery of IRS letter | Cost-effective, automated intake, eliminates the need to maintain a received fax machine |
Why SingleFax EIN by Fax ($19.99) Is the Preferred Path
With SingleFax EIN by Fax, you do not need to wrestle with IRS form formatting or maintain a dedicated telecom line:
- Step-by-Step Form Builder: Answer straightforward questions online. Our system populates a Form SS-4 PDF using your answers.
- Automated IRS Routing: The platform automatically routes and transmits the document to the correct IRS Fax-TIN unit for your location (see the current IRS SS-4 fax numbers).
- 90-Day Dedicated Return Fax Line: We allocate a dedicated US fax number to your application. When the IRS sends a reply, the service receives it on your application’s return line.
- Instant PDF Email Delivery: As soon as the IRS confirmation arrives, we convert it into a high-resolution PDF and email it directly to your inbox.
Get started now at SingleFax Get EIN for $19.99.
Common Form SS-4 Mistakes to Avoid
- Leaving Line 7b Blank: Enter the required tax identifier or, when the responsible party is ineligible for an SSN or ITIN, the permitted “foreign” or “N/A” entry.
- Name Mismatch: The business name on Line 1 must match the Articles of Organization / Certificate of Formation issued by your state exactly.
- Listing an Entity as Responsible Party: Line 7a must be an individual human being (owner, partner, director). Do not list a parent LLC or holding corporation.
- Illegible Handwriting: When completing forms manually, scan at high contrast (300+ DPI). Typed or digitally generated PDFs are strongly preferred.
- Missing Signature: The application must contain a handwritten physical signature or verified authorized signature.
Post-EIN Compliance: Next Steps
Once your EIN is assigned, remember your ongoing federal compliance obligations:
- Form 5472 and Pro Forma 1120: A foreign-owned US disregarded entity may have a Form 5472 filing requirement for reportable transactions. The due date depends on its tax year and any valid extension. Learn how to file Form 5472 by fax or use our Form 5472 filing service ($29.99).
- Form 7004 Extensions: If you need extra time to file Form 5472, read our guide on filing Form 7004 extensions by fax or submit your extension for $4.99 at File Form 7004.
Related Guides
- How to Fax the IRS in 2026 (Forms, Numbers, What You Can't Fax)
- IRS Fax Numbers Directory 2026: Verified Numbers for SS-4, 5472, and 7004
- How to File Form 5472 by Fax for Foreign-Owned US LLCs
- IRS and State Forms You Can Still Fax in 2026
Disclaimer: SingleFax provides document transmission and automated filing tools. SingleFax is not a law firm or CPA firm, and this content does not constitute legal, tax, or financial advice. Consult a licensed professional regarding your business structure and tax obligations.
Prepare an IRS fax cover sheet, keep the full TIN on the IRS form rather than the cover, and save your transmission confirmation. For other forms, use the IRS fax directory.
After you obtain the EIN, see our Form 2553 fax-number guide if your entity is eligible and plans to elect S corporation treatment.