Will this get me an EIN instantly?

No — the SS-4 is the application. The IRS issues the actual number through its online EIN assistant (immediate, weekdays), or by fax or mail. AttachKit fills and drafts the SS-4 so you walk into the assistant with every answer ready, or so you can fax/mail a clean copy.

Do I need an EIN as a sole proprietor?

Not always — a sole proprietor with no employees can often use their SSN. You generally need an EIN once you hire employees, form an LLC/partnership/corporation, or set up certain retirement plans. The SS-4 instructions list exactly who must apply; this isn't tax advice.

Is the responsible party's SSN safe?

Yes — the responsible party's SSN or ITIN stays in your browser and fills on-device. It's never uploaded to our servers and never sent to any third-party AI.

Tax · SS-4

Fill SS-4 (EIN application) online — free

Form SS-4 is how a business asks the IRS for an Employer Identification Number (EIN) — the tax ID you need to hire employees, open a business bank account, or file business returns. It's a single page you complete once. AttachKit drafts it from your profile so the IRS's finicky online EIN assistant has nothing left to surprise you with.

Who needs it: New LLCs, partnerships and corporations; sole proprietors who hire employees or set up a solo retirement plan; estates, trusts and nonprofits — anyone who needs a federal EIN.

Need a blank SS-4? Download from the source, then drop it in below.

Save your details once — supported forms auto-fill

Save your name, address, and other common fields once. Then open the blank SS-4 in the form filler below — AttachKit maps what it can from your saved profile, right in your browser with nothing uploaded.

Set up profile →

Why fill it here

Auto-fill the responsible party's name and mailing address from your saved profile.
The responsible party's SSN or ITIN fills on your device and is never uploaded — it's the most sensitive box on the form.
Draft the whole SS-4 first, then enter it into the IRS online EIN assistant (it times out after 15 minutes of inactivity) with nothing left to hunt for.
Pairs with the W-9, 1099-NEC and Schedule C you'll file once the EIN is issued.

Fill your SS-4 now

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SS-4 questions, answered

General information, not legal or tax advice

This page is general information about a commonly-used tax form. Tax law is complex and fact-specific — for advice on your return, consult a CPA, enrolled agent, or tax attorney. AttachKit fills the PDF; the IRS holds you responsible for what's on it.

Will this get me an EIN instantly?: No — the SS-4 is the application. The IRS issues the actual number through its online EIN assistant (immediate, weekdays), or by fax or mail. AttachKit fills and drafts the SS-4 so you walk into the assistant with every answer ready, or so you can fax/mail a clean copy.
Do I need an EIN as a sole proprietor?: Not always — a sole proprietor with no employees can often use their SSN. You generally need an EIN once you hire employees, form an LLC/partnership/corporation, or set up certain retirement plans. The SS-4 instructions list exactly who must apply; this isn't tax advice.
Is the responsible party's SSN safe?: Yes — the responsible party's SSN or ITIN stays in your browser and fills on-device. It's never uploaded to our servers and never sent to any third-party AI.

More forms: Form 1040 · Form 4868 · 8822 · W-9 · W-4 · Browse all 54 forms →