What is an EIN and why does your LLC need one?
An EIN is your LLC’s federal tax ID. Here’s what it does, why your bank will ask for it, and how to get one with or without a US Social Security number.
An EIN (Employer Identification Number) is a nine-digit number the IRS uses to identify your business. Think of it as a Social Security number for your LLC. You'll need one to open a US business bank account, file taxes, hire employees, and run payroll. Most states ask for it too, though some don't require it for the formation itself.
What an EIN actually does
Your EIN is how the IRS, banks, payment processors, and other businesses identify your company. It shows up on tax filings, payroll forms, 1099s, and most contracts. It doesn't expire and it's tied to the legal entity, so even if you change your business name or address, the EIN stays the same.
It is also separate from your personal Social Security number. Once you have an EIN, you can stop putting your SSN on vendor forms and customer contracts. That alone is worth the ten minutes it takes to apply.
Why your LLC needs one
Even a single-member LLC with no employees usually needs an EIN. Here are the main triggers:
- Opening a business bank account. Every US bank asks for an EIN at account opening.
- Hiring an employee or running payroll, including paying yourself if you've elected S-Corp status.
- Filing federal tax returns for the business.
- Issuing 1099s to contractors or receiving them from clients.
- Applying for business licenses, permits, or merchant accounts.
If you're trying to figure out where to open that bank account, our roundup of the top banking options for new LLCs walks through which providers actually accept new businesses.
How to get an EIN
There are two flows depending on whether you have a US Social Security number.
If you have a US SSN or ITIN. Apply online at IRS.gov. It's free, takes about ten minutes, and you'll get the EIN immediately at the end of the session. Save the PDF confirmation letter (CP 575) and the EIN both. Banks ask for the letter to verify.
If you don't have a US SSN or ITIN. You'll need to file Form SS-4 by fax or mail. Fax responses usually take 4 to 6 business days. Mail can take 4 to 6 weeks. Some formation services (we do this for international founders) submit on your behalf as a third-party designee and get a faster turnaround. For more on this path, see our guides for Indian founders, British founders, and Nigerian founders.
One thing many founders miss: you can only apply once per day per responsible party. So if you're forming multiple companies, you'll be spreading the EIN applications across separate days.
Common mistakes
A few traps we see often:
- Applying for the EIN before the LLC is approved by the state. The IRS will issue one but the entity legally doesn't exist yet, which causes problems later.
- Using the wrong responsible party. The IRS expects the actual owner or principal officer, not your accountant or lawyer.
- Losing the CP 575 letter. Banks ask for it. The IRS will send a replacement letter (147C) but it takes weeks. Save the original PDF.
Read next: If you're a foreign founder, the form you'll pair with this EIN at the bank is the W-8BEN. And once you're set up, the next decision is LLC vs C-Corp. Or skip ahead and form your LLC with EntityEngine, we'll file the EIN for you.
Keep reading
Two more posts worth your time if this one was useful.
What is a W-8BEN? A quick guide for non-US founders
The W-8BEN tells US payers that you are a foreign individual and lets you claim a lower tax-treaty withholding rate. Here is what to put on it.
Top 5 banking options for new LLCs (US and non-US founders)
Five US business banks that actually accept new LLCs, including options for non-resident founders. Pros, cons, and who each one is for.