Fill IRS Form SS-4 Online
The official SS-4 — apply for your business EIN in your browser. Fill the entity details, download, and submit by fax or mail.
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About SS-4
Form SS-4 is the application for an Employer Identification Number (EIN) — the nine-digit number the IRS uses to identify a business, the way an SSN identifies an individual. You need an EIN to hire employees, open a business bank account, file business tax returns, or form a corporation or partnership. Single-member LLCs and sole proprietors often get one too, so they can give clients an EIN on a W-9 instead of exposing their SSN.
The form asks for the legal name and mailing address of the entity, the responsible party (the person who controls the entity) and their SSN/ITIN/EIN, the entity type (sole proprietor, LLC, corporation, partnership, estate, trust, etc.), the reason you're applying, the date the business started, and your expected number of employees. Most fields are simple checkboxes and short text — the part that trips people up is the entity type and the responsible-party section, so have those clear before you start.
FormatFuse opens the official IRS SS-4 and fills it entirely in your browser — the responsible party's SSN stays on your device. Once complete, download it. The fastest route to an EIN is actually the IRS's free online application (irs.gov, issued instantly for US-based responsible parties), but the SS-4 PDF is what you need to apply by fax or mail, and many people fill it first to organize their answers before doing the online interview. International applicants without an SSN/ITIN typically must use the SS-4 by fax or phone.
How to fill SS-4
- 1
Entity name + address
Enter the legal name of the entity (lines 1–2), trade name if any, and mailing address.
- 2
Responsible party
Name the responsible party (the person who controls the entity) and their SSN, ITIN, or EIN.
- 3
Entity type + reason
Check the entity type (sole proprietor, LLC, corporation, partnership…) and the reason for applying (new business, hiring, banking…).
- 4
Business details
Add the start date, expected employees, principal activity, and accounting year.
- 5
Download + submit
Download the PDF, then apply free online at irs.gov for an instant EIN, or fax/mail the SS-4 if you can't use the online tool.
Privacy reminder. Your inputs — including your SSN, EIN, or PAN — never leave your browser. We do not log or transmit form values.
This tool fills the form, it does not give advice. It puts the information you enter onto the official PDF. It does not calculate your taxes, check your answers, or tell you if something is wrong. Compare everything to the official instructions, and if your situation is anything beyond simple, have a professional review it before you file or submit.
FormatFuse provides a privacy-first form-filling tool. We are not affiliated with the Internal Revenue Service and do not provide tax advice. Applying for an EIN is free directly from the IRS.
Frequently asked questions
Do I need an EIN, and do I have to use Form SS-4?
You need an EIN to hire employees, open a business bank account, or file as a corporation/partnership. The SS-4 is the application. US-based applicants can get an EIN instantly through the IRS's free online tool — many still fill the SS-4 first to organize their answers. International applicants without an SSN/ITIN generally apply via the SS-4 by fax or phone.
Who is the 'responsible party'?
The individual who ultimately owns or controls the entity, or who exercises effective control over it. For a single-member LLC that's usually you. The IRS requires a real person (with an SSN, ITIN, or EIN) here — not another entity, in most cases.
Is there a fee to get an EIN?
No. Applying for an EIN is completely free directly from the IRS. Be wary of third-party sites that charge a fee to 'get your EIN' — they're just filling the same free SS-4 for you. FormatFuse doesn't charge either; we only help you fill the form.
How fast will I get my EIN?
The IRS online application issues an EIN immediately upon completion (for applicants with a US SSN/ITIN). Fax applications take about four business days; mail takes around four weeks. So if you can use the online tool, that's the fastest path — fill the SS-4 here to prepare your answers, then enter them online.
Is filling the SS-4 here private?
Yes. The PDF and everything you enter — including the responsible party's SSN — stay in your browser. Nothing is uploaded. Download the completed form and submit it through the IRS's own channels.
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