Introduction
Starting a single-member LLC? You’ll need an Employer Identification Number (EIN) from the IRS—and that means filling out Form SS-4.
The problem? The form is confusing. The instructions read like they were written by lawyers for lawyers. One wrong answer and your application gets rejected.
This guide walks you through every line of Form SS-4, explains exactly what to enter for a single-member LLC, and helps you avoid the mistakes that delay most applications.
What Is IRS Form SS-4?
Form SS-4 is the IRS application for an Employer Identification Number (EIN).
Think of an EIN as a Social Security Number for your business. It’s a unique nine-digit number the IRS uses to identify your LLC for tax purposes.
Even though the form is called “Application for Employer Identification Number,” you don’t need employees to need one.
Does Your Single-Member LLC Need an EIN?
Not every single-member LLC is required to have an EIN—but most should get one anyway.
You’re required to get an EIN if your single-member LLC:
- Has employees or plans to hire
- Files excise tax returns (alcohol, tobacco, firearms)
- Has a Keogh retirement plan
- Is involved in trusts, estates, or certain non-profit activities
- Is foreign-owned and must file Form 5472
You should get an EIN even if not required if you want to:
- Open a business bank account (most banks require it)
- Keep your personal SSN off business documents
- Build business credit
- Work with vendors or contractors who need your tax ID
Bottom line: If you’re running a legitimate business, get an EIN. It’s free and takes 15 minutes online.
How to Fill Out Form SS-4: Line by Line
Here’s exactly what to enter on each line for a single-member LLC.
Lines 1–2: Business Name
Line 1 – Legal Name of Entity
Enter your LLC’s exact legal name as it appears on your state formation documents (Articles of Organization or Certificate of Formation).
✅ Correct: Acme Consulting LLC ❌ Wrong: Acme Consulting (missing LLC) ❌ Wrong: ACME CONSULTING LLC (if your documents show mixed case)
Line 2 – Trade Name (DBA)
If your LLC operates under a different name, enter it here. Otherwise, leave blank.
Example: Your LLC is “Smith Holdings LLC” but you do business as “Smith Plumbing.” Enter “Smith Plumbing” on Line 2.
Lines 3–6: Address Information
Line 3 – Executor, Administrator, Trustee, “Care Of”
Most single-member LLCs leave this blank. Only use it if someone else receives mail on behalf of your business.
Lines 4a–4b – Mailing Address
Enter the address where you want IRS correspondence sent. This can be your home address, office, or PO Box.
Lines 5a–5b – Street Address
If different from your mailing address, enter your physical business location. If same as Line 4, you can leave this blank.
Line 6 – County and State
Enter the county and state where your LLC’s principal place of business is located.
Lines 7a–7b: Responsible Party (Critical)
This is where most applications get rejected.
Line 7a – Responsible Party Name
For a single-member LLC, this is you—the owner. Enter your full legal name (first, middle initial, last).
The IRS defines the responsible party as “the person who ultimately owns or controls the entity.”
Line 7b – SSN, ITIN, or EIN
Enter your Social Security Number or Individual Taxpayer Identification Number.
⚠️ Important: Since 2018, the IRS requires an individual’s SSN or ITIN here. You cannot use another business’s EIN.
Lines 8a–8c: LLC Information
Line 8a – Is this application for a Limited Liability Company (LLC)?
Check Yes.
Line 8b – Number of LLC Members
Enter 1 for a single-member LLC.
Line 8c – State Where Organized
Enter the state where your LLC was formed (filed with the Secretary of State).
Line 9a: Type of Entity (Important)
This line confuses most people.
For a single-member LLC that hasn’t elected corporate taxation, check “Sole Proprietor”.
Wait—sole proprietor? But I formed an LLC!
Here’s why: The IRS treats single-member LLCs as “disregarded entities” by default. For tax purposes, you and your LLC are the same. Your LLC income goes on Schedule C of your personal tax return, just like a sole proprietorship.
Alternative: If your LLC needs an EIN specifically for employment taxes, excise taxes, or to file Form 5472 (foreign-owned), check “Other” and write “Disregarded entity” in the space provided.
Line 9b: Corporation Type
Leave this blank. This is only for corporations.
Line 10: Reason for Applying
Check the box that best describes why you need an EIN:
- Started new business – Most common for new LLCs
- Banking purposes – If you need it primarily to open a bank account
- Hired employees – If you’re getting an EIN because you’re hiring
Lines 11–12: Dates and Accounting
Line 11 – Date Business Started
Enter the date your LLC was officially formed (approved by the state) or the date you acquired an existing business.
Line 12 – Closing Month of Accounting Year
Most single-member LLCs use a calendar year. Enter December (or “12”).
Lines 13–14: Employees
Line 13 – Highest Number of Employees Expected
Enter your best estimate. If you don’t plan to hire anyone, enter 0 for each category.
Line 14 – Do you expect to have $1,000 or less in employment tax liability?
If you have no employees, skip this. If you do, answer based on expected quarterly payroll.
Lines 15–17: Wages and Business Activity
Line 15 – First Date Wages Paid
If you’re hiring employees, enter when you expect to first pay wages. Otherwise, leave blank.
Line 16 – Principal Activity
Check the box that best describes what your business does (construction, retail, real estate, etc.).
Line 17 – Describe Your Business
Briefly describe your products or services. Example: “Marketing consulting services” or “Residential plumbing repairs.”
Line 18: Previous EIN
Has the applicant entity ever applied for or received an EIN?
Answer honestly. If your LLC previously received an EIN, check Yes and enter the old number if you have it.
Third-Party Designee (Optional)
If someone else (accountant, attorney, service) is helping you apply, you can authorize them to receive the EIN and answer IRS questions. Otherwise, leave blank.
Signature Section
The responsible party (you, the owner) must sign and date the form. If applying online, you’ll confirm your identity electronically.
How to Submit Form SS-4
You have three options:
| Method | Timeframe | Best For |
|---|---|---|
| Online | Instant (EIN issued immediately) | US-based applicants with SSN/ITIN |
| Fax | 4 business days | Those who can’t apply online |
| 4–5 weeks | Last resort only |
Online is the best option. The IRS EIN Assistant is available Monday–Friday, 7 AM–10 PM Eastern at irs.gov.
You’ll receive your EIN immediately upon approval and can download your confirmation letter (CP 575) right away.
⚠️ Warning: The online application times out after 15 minutes of inactivity, and you can’t save progress. Have all your information ready before starting.
Common Mistakes That Get Applications Rejected
These errors cause most EIN application problems:
- LLC name doesn’t match state records – Spelling, punctuation, and capitalization must be exact
- Wrong entity type on Line 9a – Single-member LLCs should select “Sole Proprietor” (not Corporation or Partnership)
- Incorrect responsible party – Must be an individual with an SSN or ITIN, not another business
- Applying before LLC is formed – Your LLC must be approved by your state before you apply for an EIN
- Multiple applications – You can only apply for one EIN per responsible party per day
- Not printing confirmation – If you don’t download your EIN letter immediately, you’ll have to wait 30 days to request a copy
Frequently Asked Questions
Can a single-member LLC apply for an EIN online?
Yes. If you have an SSN or ITIN and your principal business is in the US, you can apply online through the IRS website and receive your EIN instantly.
Do I need an EIN if I have no employees?
Not technically required in most cases, but strongly recommended. Banks typically require an EIN to open a business account, and it keeps your personal SSN private.
How long does it take to get an EIN?
Online applications are approved immediately. Fax applications take about 4 business days. Mail applications take 4–5 weeks.
Can I apply for an EIN without an SSN?
Yes, but not online. International applicants or those without an SSN must apply by fax or mail, or call the IRS at 267-941-1099.
What if I make a mistake on Form SS-4?
Minor errors can often be corrected by calling the IRS Business Tax Line at 800-829-4933. More serious errors may require submitting a new application.
Is it free to get an EIN?
Yes. The IRS issues EINs at no charge. Beware of third-party websites that charge fees for this free service.
Skip the Confusion—Fill Your SS-4 the Easy Way
Form SS-4 isn’t complicated once you understand it, but it’s easy to make mistakes that delay your application or get it rejected.
If you’d rather not worry about entering the wrong thing, FillMyForm.app guides you through the process step by step. Just answer simple questions about your business, and we’ll help you complete the form correctly—no IRS jargon, no guesswork.
→ Fill out Form SS-4 with FillMyForm.app
Last updated: January 2025. Information verified against current IRS Form SS-4 instructions (Rev. December 2025).