IRS Form SS-4 (Apply for an EIN) document pack

Your business needs an EIN to do almost anything serious — open a bank account, hire an employee, file partnership taxes, sponsor a 401(k). The IRS gives them out for free in 15 minutes online; the paper Form SS-4 is the slow lane.

Who this pack is for

You're starting or have just started a business — an LLC, partnership, corporation, or sole proprietorship that wants to separate business and personal finances — and you need an Employer Identification Number. You may have already filed Articles of Organization with your state. You may be a sole proprietor who wants an EIN for privacy reasons (so you don't give your SSN to every client). You may be a foreign-owned U.S. entity that has to apply by mail or fax because the online portal requires a U.S.-based responsible party. You want to fill out the SS-4 correctly the first time so you don't get sent back for a rejection or end up with the wrong tax classification on file.

When to use it

Apply for an EIN immediately after your state approves your formation paperwork. The IRS recommends online application — instant issuance, no fee, available at irs.gov/EIN — for any responsible party with a valid SSN or ITIN. Use the paper SS-4 only if (1) the responsible party doesn't have an SSN/ITIN (foreign founder), (2) the entity type isn't supported online (rare), or (3) you need a paper trail for documentation purposes. Mail processing takes 4–6 weeks; fax is 4 business days. The pack fills the values either way.

What it doesn't cover

This is the IRS Form SS-4 for getting an Employer Identification Number. It does not file your state's formation paperwork (Articles of Organization, Articles of Incorporation, Certificate of Formation — those go to the Secretary of State of the state where you're forming). It does not elect tax treatment beyond what's selected on the SS-4 (S-corp election requires Form 2553, separately filed). It does not register you for state tax accounts, sales tax permits, or unemployment insurance — those are state-specific filings done after you have the EIN. It does not handle nonprofit / 501(c)(3) recognition (Form 1023) or trust EINs with complex grantor / non-grantor questions.

Common questions

Does every business need an EIN?

Practically yes for most modern businesses, but technically no. Sole proprietors with no employees can use their SSN for tax purposes — but they'll be giving their SSN to every client (W-9), every bank, every vendor. Get the EIN; it costs nothing and protects your SSN. LLCs, partnerships, and corporations need one. Single-member LLCs that file as disregarded entities can technically use the owner's SSN but most banks won't open a business account without an EIN.

What's the 'responsible party'?

The natural person who controls the entity — typically the principal owner, principal officer, or grantor of a trust. Must be an individual with a valid SSN or ITIN (online application requires one of these). For multi-owner entities, pick one person whose name will appear on the IRS records as the responsible party; this is the contact the IRS will send notices to. If the responsible party changes (you sell the business, you appoint a new managing member), file Form 8822-B to update the IRS within 60 days.

What entity type do I pick?

Sole proprietorship (no entity, just you doing business in your name); single-member LLC (one owner); multi-member LLC (two or more owners — defaults to partnership for tax); partnership (general or limited, no LLC); C-corporation; S-corporation (you'll file Form 2553 separately to elect S status). Pick what matches your state filing. LLCs have a sub-question on the SS-4 about how many members and federal tax classification — get this right; it's hard to undo later.

When did the business start?

The 'date business started or acquired' is when you began operations or formed the entity. For new LLCs, it's the formation date on the state filing. For sole proprietors with new EINs, it's when you started the business. The IRS uses this for tax-year alignment and for some payroll-related deadlines; pick a real date you can document.

What's the difference between EIN and other tax IDs?

EIN (Employer Identification Number) is the federal entity tax ID, issued by the IRS, free, used for federal tax filings. SSN (Social Security Number) is your personal tax ID. ITIN (Individual Taxpayer Identification Number) is for non-residents who need a U.S. tax ID but can't get an SSN. State Tax ID is your state's separate ID for state income / sales / payroll tax — different number, different agency, different application process.

How do I get the EIN fastest?

Online at irs.gov/EIN, between 7 a.m. and 10 p.m. Eastern, weekdays. The application takes 10–15 minutes; you get the EIN immediately on the confirmation page (download it as a PDF before closing the window — you cannot retrieve it again from the IRS website). Online application requires the responsible party to have a valid SSN or ITIN. If you don't, you'll fax or mail the SS-4 and wait days to weeks.

Should I get an EIN before or after forming the LLC?

After. The state forms the LLC; the IRS issues the EIN. The SS-4 asks for the LLC's legal name and state of formation, which means the LLC must already exist. Apply for the EIN within a few days of state approval — most banks won't open a business account or wire-receive funds without it.

Sources

Primary legal sources cited above. These link to free, public versions of the statutes, regulations, and case law referenced in this pack.

Pike provides plain-language legal information, not legal advice. State and local rules change. If money, custody, or your housing is on the line, talk to a licensed attorney or your local legal aid office.