An Employer Identification Number (EIN) is a nine-digit number the IRS uses to identify your business for tax purposes. Think of it as a Social Security Number for your company. You need it before you can open a business bank account, hire anyone, or file a business tax return.
The good news: it's free and takes about 5 minutes to get online. Here's exactly how.
Who Needs an EIN?
You need an EIN if you:
- Have a corporation or partnership (required)
- Have employees or plan to hire any
- Have a Keogh retirement plan
- Are required to file excise, employment, or alcohol/tobacco/firearms tax returns
- Withhold taxes on income paid to a non-resident alien
You also benefit from having one even if you're not required to — especially as a sole proprietor or single-member LLC. Using an EIN instead of your Social Security Number on business documents reduces your identity theft exposure.
How to Apply Online (Fastest Method)
- Go to IRS.gov and search "EIN online application" or navigate to the EIN Assistant directly
- Select the entity type that matches your business (sole proprietor, LLC, corporation, partnership, etc.)
- Answer questions about your business structure, address, and reason for applying
- Review and submit
You'll receive your EIN immediately — it appears on screen and can be saved or printed. The IRS also mails a confirmation letter (CP 575) to your business address within 4 weeks, which some banks require as verification.
Important: The online application is only available Monday–Friday, 7am–10pm Eastern time. If you apply outside those hours, you'll get an error message.
What If You Can't Apply Online?
If you're a foreign applicant or outside the US, you can apply by:
- Fax: Form SS-4 to (855) 641-6935. You'll get your EIN within 4 business days.
- Mail: Form SS-4 to the appropriate IRS address. Takes 4–5 weeks — avoid this if you're in a hurry.
- Phone: International applicants only — call (267) 941-1099.
For US-based founders, online is always faster.
Information You'll Need
Have this ready before you start:
- Legal name of the entity (exactly as it appears in your formation documents)
- Principal business address
- Name and SSN/ITIN of the responsible party (the individual who controls the entity — usually the founder)
- Type of entity (LLC, corporation, etc.)
- State of formation
- Reason for applying (started a new business, hired employees, banking requirements, etc.)
- Number of employees you expect to hire in the next 12 months
After You Get Your EIN
Save it immediately. The IRS website won't show it again after you leave the confirmation page. Copy it to a password manager or secure document.
Then use it to:
- Open a business bank account — most banks require your EIN and formation documents (Certificate of Incorporation or Articles of Organization)
- Set up payroll if you're hiring employees
- Register for state tax accounts — most states have their own employer registration separate from the federal EIN
- File federal taxes — your EIN goes on every business tax return
Common Mistakes
Applying before your entity is formed. Your EIN is tied to your entity. Apply after your Certificate of Incorporation or Articles of Organization are filed and approved — not before.
Using the wrong entity type. If you have a single-member LLC, choose "Limited Liability Company" and indicate one member — not "Sole Proprietor." The entity type affects how the IRS treats your income.
Losing the number. If you lose your EIN, you can call the IRS Business & Specialty Tax Line at (800) 829-4933 to retrieve it, but it takes time. Just save it properly the first time.
EIN vs. State Tax ID
An EIN is federal. Many states also require a separate state tax identification number for:
- State income tax withholding
- State sales tax collection
- Unemployment insurance
These are different registrations. After you get your federal EIN, check your state's Department of Revenue or Department of Labor website for any additional registrations required.
Founder Kit walks you through both federal and state registration requirements as part of the federal registration guide — so you don't have to hunt down each state's process separately.