What Is Form SS-4?
IRS Form SS-4, officially titled "Application for Employer Identification Number," is the federal form used to obtain an Employer Identification Number (EIN) from the Internal Revenue Service. The EIN is a unique nine-digit number that serves as the federal tax identification for business entities, trusts, estates, and other organizations that are required to file tax returns or make tax payments. Think of the EIN as the business equivalent of a Social Security number — it identifies the entity in all interactions with the IRS, state tax agencies, banks, and other institutions that require tax identification. Every employer that pays wages must have an EIN, and the number appears on every employment tax return (Forms 941, 940, W-2), business income tax return (Forms 1120, 1120-S, 1065), and information return the entity files.
Form SS-4 collects the information the IRS needs to establish the entity in its records: the legal name and trade name of the entity, the responsible party's name and taxpayer identification number, the mailing and physical addresses, the type of entity (sole proprietorship, partnership, corporation, LLC, trust, estate, government agency, or other), the reason for applying (starting a new business, hiring employees, banking purposes, compliance requirements), and the expected number of employees and first date wages will be paid. The form also asks about the principal business activity and the specific products or services the entity provides, which the IRS uses to classify the entity by North American Industry Classification System (NAICS) code for statistical and audit selection purposes.
While the online EIN application has largely replaced paper Form SS-4 submissions for domestic applicants, the form itself remains the foundational document that defines the information requirements. International applicants who lack a U.S. address must still submit Form SS-4 by fax or mail, and many business formation attorneys use the form as a worksheet to gather the necessary information before completing the online application on behalf of their clients. Understanding each line of Form SS-4 ensures that the EIN application is completed correctly the first time, avoiding delays that can hold up bank account openings, payroll setup, and first-year tax filings.
Apply Online
Receive your EIN immediately through the IRS online assistant for domestic applicants.
All Entity Types
Covers corporations, partnerships, LLCs, trusts, estates, and nonprofit organizations.
Permanent Number
Your EIN never expires and stays with the entity for its entire existence.
Form SS-4 Preview
Form SS-4
Application for Employer Identification Number
1. Legal name of entity
2. Trade name of business (if different)
7a. Name of responsible party
SSN/ITIN:
9a. Type of entity
□ Sole proprietor □ Partnership □ Corporation □ LLC
SIGNATURE
DATE
Who Needs an EIN?
The IRS requires an Employer Identification Number for a wide range of entities and situations. The following table identifies the most common scenarios requiring EIN applications:
| Entity / Situation | EIN Required? | Details |
|---|---|---|
| Corporation (C-Corp or S-Corp) | Always required | Must obtain EIN at formation; used on all corporate tax returns and employment filings |
| Partnership / Multi-Member LLC | Always required | Files Form 1065 and issues Schedule K-1s under the partnership EIN |
| Single-Member LLC | Required if has employees | Disregarded entity can use owner SSN unless it has employees or files excise tax returns |
| Trust or Estate | Required for irrevocable trusts and estates | Revocable trusts use grantor SSN until grantor death; estates need EIN immediately |
| Sole Proprietor with Employees | Required | Must have EIN to file employment tax returns and issue W-2s to employees |
| Nonprofit Organization | Always required | Must obtain EIN before applying for tax-exempt status (Form 1023 or 1023-EZ) |
How to Apply for an EIN
Determine Eligibility and Entity Type
Before applying, confirm that you need a new EIN rather than using an existing one. Identify your entity type (sole proprietorship, partnership, corporation, LLC, trust, estate, nonprofit, government) because this determines which lines of Form SS-4 you complete and how the IRS classifies your entity. If you are forming an LLC, determine its federal tax classification (disregarded entity, partnership, or corporation) before applying, as this election affects how the IRS processes your application and which tax returns you will file.
Identify the Responsible Party
Every EIN application must identify a responsible party — the individual who controls or manages the entity. For corporations, this is typically the president or CEO; for partnerships, a general partner; for LLCs, a managing member or manager; for trusts, the grantor or trustee. The responsible party must provide their SSN or ITIN. If you are a third-party designee (attorney, accountant, enrolled agent) applying on behalf of the entity, you will identify yourself as the designee while providing the responsible party's information.
Choose Your Application Method
The IRS offers four methods: Online (fastest, immediate EIN for domestic applicants with SSN/ITIN), Fax (submit Form SS-4 to the appropriate fax number based on your location, receive EIN within 4 business days), Mail (mail Form SS-4 to the address in the instructions, 4-6 week processing), or Telephone (international applicants only, call 267-941-1099, immediate EIN during the call). The online method is recommended for all domestic applicants because it provides instant confirmation and eliminates processing delays.
Complete the Application
Provide the entity's legal name (exactly as it appears on formation documents), trade name or DBA if different, mailing and physical addresses, responsible party information, entity type, reason for applying, expected number of employees, first date wages will be paid, principal business activity, and specific products or services. For the online application, have all information ready before starting — the session times out after 15 minutes of inactivity. For fax and mail, use the most current version of Form SS-4 (check IRS.gov for the latest revision).
Record and Safeguard Your EIN
Once issued, record your EIN immediately and store the confirmation notice (CP 575 for online/fax/phone, or the official letter for mail applications) in a secure location. You will need the EIN for your first bank account application, initial tax filings, state registrations, and any business licenses that require federal tax ID. If you applied online, print the confirmation page before closing the browser. If the EIN does not appear in the e-file system within two weeks, contact the IRS Business and Specialty Tax Line at 800-829-4933.
Responsible Party Rules
The IRS significantly tightened its responsible party requirements in recent years to combat EIN fraud and identity theft. Under current rules, the responsible party identified on Form SS-4 must be an individual (a natural person) for most entity types — the IRS no longer accepts another entity name as the responsible party for corporations, partnerships, or LLCs. The only exceptions are government entities and certain military organizations where an individual responsible party cannot be identified.
The responsible party designation carries practical significance beyond the application itself. Banks increasingly verify the responsible party listed with the IRS when processing business account applications under Know Your Customer (KYC) and anti-money laundering (AML) regulations. If the responsible party on the EIN records does not match the individual presenting identification at the bank, the account opening may be delayed or denied. When the responsible party changes — due to ownership transfer, officer replacement, or death — the entity must file Form 8822-B within 60 days to update the IRS records. Failure to update creates a mismatch that can cause problems with bank access, tax correspondence delivery, and identity verification during IRS phone inquiries.
Third-Party Designee Limitation
If you authorize a third-party designee (attorney, CPA, enrolled agent) to apply for the EIN on your behalf, the designee's authority is limited to receiving the EIN and resolving issues related to the application. The designee does not have authority to represent the entity on other tax matters unless a separate Form 2848 (Power of Attorney) is filed. The third-party designee authorization expires 60 days after the EIN is issued.
Frequently Asked Questions
Official Resources
Authoritative IRS resources for EIN applications, entity classification, and responsible party requirements.
IRS - Apply for EIN Online
The official IRS online EIN application (EIN Assistant) for domestic applicants with valid SSN or ITIN.
IRS - About Form SS-4
Official form page with current Form SS-4, instructions, and recent revision information for EIN applications.
IRS - Do You Need an EIN?
IRS decision tool to help determine whether your entity or situation requires a new Employer Identification Number.
IRS - Form 8822-B (Change of Responsible Party)
Form for notifying the IRS of changes to the responsible party or business address associated with an EIN.
IRS - Employer ID Numbers Overview
Comprehensive IRS resource on EINs covering application methods, responsible party rules, lost EIN procedures, and common questions.
SBA - Get Federal & State Tax ID Numbers
Small Business Administration guide covering both federal EIN and state tax registration requirements for new businesses.
Apply for Your EIN
Complete your Employer Identification Number application with our guided Form SS-4 preparation covering entity classification, responsible party designation, and application submission.
Create DocumentNo account required. Free to create and preview.