How to Fax IRS Form SS-4 — Apply for an Employer Identification Number
Form SS-4 is how a business, estate, trust, or other entity applies for an Employer Identification Number (EIN), the federal tax ID used to open bank accounts, hire employees, and file returns. It captures the entity's legal name, structure, responsible party, and reason for applying. While many domestic applicants can get an EIN instantly online, fax remains a standard channel — especially for applicants without a U.S. Social Security number for the responsible party, or when the online tool cannot process a particular case. The form must name a true responsible party who controls the entity.
Why this form is faxed
When the online assistant does not fit an applicant's situation, the Instructions for Form SS-4 describe fax as an accepted way to apply, and it is markedly faster than mailing the form. The IRS generally returns an EIN by fax within a few business days when a return fax number is provided. Faxing also gives the applicant a dated record that the application was submitted.
Where it goes
The correct submission channel depends on whether the entity's principal location is inside the United States — the Instructions for Form SS-4 list separate fax destinations for domestic applicants and for those with no legal residence or principal office in the U.S. Confirm the current number for your situation on the latest instructions rather than reusing an old one, since the IRS updates these by processing location.
How to fax IRS Form SS-4 (Application for Employer Identification Number)
- 1Complete the entity's legal name, mailing address, and structure exactly as it will appear on future filings
- 2Name the responsible party and provide their identifying number, or follow the instructions for applicants without a U.S. taxpayer ID
- 3State the reason for applying and the expected first date wages are paid if the entity will have employees
- 4Sign and date the application, and confirm the current fax destination for domestic or international applicants in the Instructions for Form SS-4
- 5Log in to Send FAX Mail, upload the signed PDF, enter the confirmed IRS number, and send
- 6Save the transmission confirmation and watch for the return fax carrying the assigned EIN
Handling sensitive information
Form SS-4 ties a responsible party's Social Security or individual taxpayer number to a new business entity, so a leaked application can seed both identity theft and fraudulent business registrations. Enter the responsible party carefully and send only to a number confirmed against current instructions, since a misrouted SS-4 exposes the person who legally controls the entity.
What’s current · as of July 2026
Recent updates
Federal agencies still write fax into new rules and notices
The Federal Register — the daily journal of U.S. federal rulemaking — regularly publishes rules and notices that reference fax as an accepted or required submission channel for filings with agencies like the IRS, SSA, and CMS. That is why fax remains a live requirement for many official forms even as electronic portals expand.
Federal Register →
Faxing IRS Form SS-4 (Application for Employer Identification Number) — FAQ
Most domestic applicants whose responsible party has a U.S. taxpayer number can get an EIN immediately through the IRS online assistant. Fax is the practical route when the online tool doesn't fit — for example, a responsible party without a Social Security number, or an entity type the assistant won't process. Check which path your entity qualifies for before choosing.
When you provide a return fax number, the IRS typically faxes the assigned EIN back within about four business days of processing your SS-4. Applying by mail takes considerably longer. Save your send confirmation so you know when the clock started if the return fax is slow.
The responsible party is the individual who actually controls or directs the entity and its funds — not a nominee or a paid filing service. The IRS expects a real person with a taxpayer identification number in that field for most applicants. Naming someone who doesn't truly control the entity can create problems later when the EIN is used.
No. Each separate legal entity needs its own SS-4 and its own EIN, because the number identifies one specific taxpayer. If you are forming multiple entities, file a distinct application for each. Reusing an EIN across unrelated businesses causes filing and banking conflicts down the line.
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