Getting Started · 2026-04-13
How to Apply for EIN Online: SS-4 Form Walkthrough
A field-by-field walkthrough of IRS Form SS-4 for obtaining your Employer Identification Number. Covers the online, fax, and mail application methods, explains every required field, and why the address you enter on SS-4 becomes your IRS address of record for all future correspondence.
What Is an EIN and Why You Need One
An Employer Identification Number (EIN) is a nine-digit number the IRS assigns to business entities for tax identification purposes. Think of it as a Social Security Number for your company. Every LLC, corporation, and partnership that operates in the United States needs one.
You need an EIN to open a business bank account, file federal taxes, hire employees, and apply for business credit. Most banks will not even begin the account application process without an EIN. It is free to obtain directly from the IRS, and there is no reason to pay a third-party service to get one for you.
The application form is called Form SS-4, and the IRS offers three ways to submit it: online, by fax, and by mail. Each method has different requirements and processing times, and the one you choose depends on whether you have a US Social Security Number or Individual Taxpayer Identification Number.
Three Ways to Apply: Online, Fax, and Mail
Online Application (Recommended if Eligible)
The IRS online EIN application is available at irs.gov and is by far the fastest method. You complete the form in a single session and receive your EIN immediately upon submission. The entire process takes about 15 minutes.
Requirements for online application:
You must have a valid SSN or ITIN (Individual Taxpayer Identification Number)
The responsible party must have a US taxpayer identification number
You must complete the application in one session (it does not save progress)
Available Monday through Friday, 7 AM to 10 PM Eastern Time
If you are a non-US resident without an SSN or ITIN, you cannot use the online application. You must use fax or mail instead.
Fax Application
Fax your completed SS-4 form to the IRS and they will fax back your EIN assignment. Processing time is 4 to 6 business days for domestic filers. International applicants fax to a different number and may wait longer.
Fax numbers:
Domestic: (855) 641-6935
International: (304) 707-9471
Mail Application
Mail your completed SS-4 to the IRS. Processing time is 6 to 8 weeks. This is the slowest method and should only be used as a last resort.
Mailing address:
Internal Revenue Service, Attn: EIN Operation, Cincinnati, OH 45999
For international applicants without SSN/ITIN, the fax method is the practical choice. Waiting 6 to 8 weeks for mail processing delays everything downstream: bank account opening, payment processor setup, and business operations.
SS-4 Form: Field-by-Field Guide
Here is every field on Form SS-4 and what to enter for a standard single-member LLC.
Line 1: Legal Name of Entity
Enter the exact legal name as it appears on your Articles of Organization. This must match character for character. If your formation document says "Acme Holdings LLC" do not enter "Acme Holdings, LLC" with a comma. Banks cross-reference your EIN letter against your formation documents, and any mismatch can cause your business bank account application to fail.
Line 2: Trade Name / DBA
If your business operates under a different name than its legal name, enter it here. If not, leave this blank. Do not invent a trade name just to fill the field.
Line 3: Executor, Administrator, Trustee
Leave blank for a standard LLC. This field applies to estates and trusts.
Lines 4a-4b: Mailing Address
This is the most consequential field on the entire form. The address you enter here becomes your IRS address of record. All future IRS correspondence goes to this address, including your CP 575 EIN confirmation letter, annual tax notices, and any audit communications.
If you enter a virtual mailbox address or a temporary address that you later lose access to, you will miss critical IRS correspondence. If the IRS cannot reach you, penalties and compliance issues compound silently.
Enter a stable, long-term physical address where you can reliably receive IRS mail. For LLC founders using a physical operations hub in Wyoming, the sublease address serves this purpose because it is a real physical address tied to your business through a legal agreement.
Lines 5a-5b: Street Address (if different)
If your physical business location differs from your mailing address, enter it here. For most single-member LLCs operating from a single address, this is the same as Lines 4a-4b.
Line 6: County and State
Enter the county and state where your business is physically located. For a Wyoming LLC operating from Laramie, this would be Albany County, Wyoming.
Line 7a-7b: Responsible Party
Enter the name and SSN/ITIN of the person who controls, manages, or directs the entity. For a single-member LLC, this is you. The IRS requires a responsible party with a US taxpayer ID for all EIN applications.
For non-US founders: if you do not have an SSN or ITIN, you must apply for an ITIN first (Form W-7) or use the fax/mail method with your foreign identification.
Line 8a: Type of Entity
Check "Limited Liability Company" and enter the number of members. For a single-member LLC, enter "1".
Line 8b: State or Foreign Country
Enter the state where your LLC was formed. If you formed in Wyoming, enter "Wyoming."
Line 9a: Reason for Applying
Check "Started new business" for a newly formed LLC.
Line 10: Date Business Started
Enter the date your LLC was officially formed (the date on your Articles of Organization, not the date you are filling out this form).
Line 11: Closing Month of Accounting Year
Enter "December" for a standard calendar year. Most single-member LLCs use a calendar year (January through December) for tax purposes.
Lines 12-14: Employees and Payroll
If you do not plan to hire employees immediately, enter "0" for expected employees and "N/A" for the first payroll date. You can update this later.
Line 15: First Date Wages Paid
Enter "N/A" if you have no employees yet.
Line 16: Principal Business Activity
Select the category that best describes what your business does. Be specific. "Retail" is not as useful as "E-commerce retail sales" or "Software development services." Banks and the IRS use this information differently, and vague descriptions raise questions.
Line 17: Business Description
Write one to two sentences describing your actual business activity. This should match what you tell banks, payment processors, and other institutions. Consistency across all your business documents matters.
Line 18: Previous EIN
If this entity has never had an EIN before, check "No."
After You Submit: The CP 575 Letter
When the IRS assigns your EIN, you receive a confirmation called the CP 575 notice. If you applied online, you can download this immediately. If you applied by fax or mail, it arrives as a physical letter to the address on Line 4a.
The CP 575 is one of the most important documents your business will ever receive. Banks specifically ask for it during account applications. It serves as official IRS confirmation that your EIN was assigned to your entity. Some banks accept a screenshot or PDF of the online confirmation, but others insist on the original CP 575 letter.
If you lose your CP 575, you can request a replacement called a 147C letter by calling the IRS Business and Specialty Tax Line at (800) 829-4933. Processing takes 45 to 60 days.
Store your CP 575 securely. Make digital copies. You will need it repeatedly throughout the life of your business.
Common Mistakes That Cause Problems
Name mismatch between SS-4 and formation documents. If your Articles of Organization say "Global Trade Solutions LLC" and your SS-4 says "Global Trade Solutions, LLC" (with a comma), some banks will flag this as a mismatch during KYB verification. Copy the name exactly.
Using a temporary address on Line 4a. Founders who use a friend's address, a hotel, or a temporary mailbox often lose access to that address later. When the IRS sends correspondence and it gets returned, your account gets flagged.
Applying online with wrong entity type. Selecting "sole proprietor" instead of "LLC" on the online application creates a different type of EIN that cannot be easily changed. You would need to apply again.
Not keeping records of the application. If you apply by fax or mail, keep a copy of the signed SS-4 form. If the IRS has questions or loses your application, you need proof of what you submitted.
Timeline: What Happens After EIN Assignment
Once you have your EIN and CP 575, the next steps are:
1. Open a business bank account using your EIN, formation documents, and proof of business address
2. Register with your state for any required state-level tax IDs
3. Apply for business licenses if your industry requires them
4. Set up payment processors (Stripe, PayPal, etc.) which all require your EIN
The EIN is the foundation. Without it, almost nothing else in your business infrastructure can move forward.
For detailed guidance on how the address on your EIN application affects bank approval, read EIN Application Address Requirements for Non-Residents. For a broader overview of what an EIN is and why every LLC needs one, see What Is an EIN? Employer Identification Number Explained.
Key Takeaways
The SS-4 form is straightforward, but the details matter. The address you enter becomes your IRS address of record. The entity name must match your formation documents exactly. The responsible party must have a US taxpayer identification number for online filing.
Get these right the first time. Correcting EIN information after assignment is possible but slow and bureaucratic. The 15 minutes you spend carefully completing the SS-4 save weeks of corrections later.