Form SS-4 Instructions: How to Fill Out the EIN Application

To get an Employer Identification Number (EIN), you need to fill out IRS Form SS-4 and submit it to the IRS. The form asks for your business name, entity type, responsible party information, and the reason you're applying. You can file online, by fax, or by mail. This guide walks through every section of the form so you know exactly what to enter.

An Employer Identification Number (EIN) is a 9-digit tax ID the IRS assigns to your business. It works the same way a Social Security Number (SSN) works for an individual — it identifies your business on federal tax filings and lets you operate legally for tax purposes.

You'll need an EIN to open a business bank account, apply for business credit, hire employees, file business tax returns, and handle payroll. Even if you don't plan to hire anyone right away, most banks require an EIN before they'll open a business checking account.

Most LLCs, corporations, partnerships, and other formal business entities need an EIN. Sole proprietors with no employees can sometimes use their SSN instead, but getting an EIN keeps your personal number off business documents — which is worth doing.

Form SS-4, Application for Employer Identification Number, is available directly from the IRS. You can download the PDF from irs.gov, apply online through the IRS EIN Assistant, or request the form by phone. The IRS recommends completing the form before you contact them to apply.

The online EIN application is the fastest option — you get your EIN immediately after completing it. The online tool is available Monday through Friday, 7 AM – 10 PM ET. Outside those hours, you'll need to use fax or mail.

Form SS-4 has about 18 lines. Most are straightforward, but a few trip people up — especially the responsible party section and the entity type selection. Here's what each section requires.

Lines 1–2: business name and trade name

Line 1 is your legal business name — the name that appears on your Articles of Organization, Articles of Incorporation, or other formation documents. Spell it exactly as it appears on those documents. Line 2 is for your trade name or DBA (doing business as) if your business operates under a different name than the legal name on Line 1. Leave Line 2 blank if you don't use a trade name.

Lines 3–6: executor, trustee, or care-of name and address

Line 3 is for the name of an executor, administrator, trustee, or care-of person if the EIN is being applied for on behalf of a trust, estate, or similar entity. Most small business owners leave this blank. Lines 4a and 4b are the mailing address for the business. Lines 5a and 5b are the physical street address if it's different from the mailing address. Lines 6 asks for the county and state where the business is located.

Lines 7a–7b: responsible party

This section catches people off guard. Line 7a is the name of the responsible party — the individual who controls, manages, or directs the entity and exercises ultimate effective control over it. For most small businesses, that's the owner. The responsible party must be an individual, not another business entity.

Line 7b requires the responsible party's SSN, Individual Taxpayer Identification Number (ITIN), or EIN if they don't have an SSN or ITIN. Do not enter the business's own EIN here — the IRS is asking for the responsible party's personal tax ID, not the entity's. For sole proprietorships, enter the owner's name on Line 7a and their SSN on Line 7b.

Lines 8a–8b: LLC status

Line 8a asks whether the entity is an LLC. Check yes or no. If yes, Line 8b asks how many members the LLC has. A single-member LLC enters 1. A multi-member LLC enters the number of members. This affects how the IRS classifies your LLC for tax purposes by default.

Line 9a: entity type

Line 9a asks you to select your entity type: sole proprietorship, partnership, corporation, S Corporation, personal service corporation, church or church-controlled organization, other nonprofit organization, estate, trust, or other. Select the type that matches your legal structure. If you formed an LLC, you'll have already answered Lines 8a and 8b — Line 9a is for non-LLC entities or for LLCs that have elected corporate tax treatment.

Line 10: reason for applying

Line 10 asks why you're applying for an EIN. Common reasons include: started a new business, hired employees, banking purposes, changed type of organization, or purchased a going business. If you're applying because you started a new business, you'll also need to enter the type of business and the date it started. Most new business owners select "started a new business" or "banking purposes."

Lines 11–18: business details, employees, and signature

The remaining lines cover your business start or acquisition date (Line 11), the closing month of your accounting year (Line 12), the highest number of employees expected in the next 12 months (Lines 13–15), whether you expect to file Form 944 (Line 16), the principal activity of your business (Line 17), and the specific products or services you provide (Line 18). Line 18 is where you describe what your business actually does — be specific. "Retail clothing sales" is better than "retail."

The signature section at the bottom requires the name, title, and signature of the applicant or an authorized third-party designee. If someone else is filing on your behalf, they fill in the third-party designee section with their name, phone number, and fax number.

You have 4 ways to submit Form SS-4: online, by phone, by fax, or by mail. Online is the fastest — you get your EIN the same day. The other methods take longer and are worth knowing if the online tool isn't available when you need it.

• Online: Use the IRS EIN Assistant at irs.gov/ein. Available Monday through Friday, 7 AM – 10 PM ET. You receive your EIN immediately after completing the application.
• By phone: International applicants can call 267-941-1099 (not a toll-free number), Monday through Friday, 6 AM – 11 PM ET. Have your completed Form SS-4 ready before you call.
• By fax: Fax your completed Form SS-4 to the IRS. Processing takes about 4 business days. The IRS will fax your EIN back to you if you include a return fax number.
• By mail: Mail your completed Form SS-4 to the IRS address for your state. Processing takes 4–5 weeks. Use this method only if the others aren't available to you.

Online applications are processed immediately — you get your EIN as soon as you finish the form. Fax applications take about 4 business days. Mail applications take 4–5 weeks. If you need your EIN quickly to open a bank account or hire employees, the online application is the right choice.

Once the IRS issues your EIN, you'll receive a confirmation notice — either online (CP 575 notice) or by mail. Keep this document. Banks, lenders, and state agencies will ask for your EIN, and having the original IRS confirmation makes it easier to verify.