An Employer Identification Number (EIN) is a unique nine-digit number issued by the IRS to identify a business for tax purposes. Think of it as a Social Security Number for your company. It’s used to open business bank accounts, apply for loans, file taxes, and hire employees. Whether you’re running a corporation, partnership, or even a sole proprietorship, having an EIN is often required—and even when it isn’t, it can still offer important benefits.
Many new business owners encounter the EIN early in the setup process, but not everyone understands when it’s required or how to get one. In this guide, we’ll walk through who needs an EIN, why it matters, how to apply, and when you might need a new one.
Who Needs an EIN?
Not every business is legally required to have an EIN, but many are—and in some cases, it’s simply a smart move. The IRS requires you to obtain an EIN if your business:
- Hires employees
- Operates as a corporation or partnership
- Files employment, excise, or alcohol, tobacco, and firearms tax returns
- Withholds taxes on income (excluding wages) paid to a non-resident alien
- Has a Keogh retirement plan
- Is involved with certain types of organizations, like trusts, estates, or nonprofit
If your business falls into one of these categories, an EIN isn’t optional. You’ll need it to stay compliant with tax laws and employment regulations.
But even if you’re not legally required to have one, an EIN can still be helpful. Many sole proprietors and single-member LLCs choose to get an EIN to:
- Separate personal and business finances
- Open a business bank account
- Apply for business licenses
- Reduce identity theft risk by using the EIN instead of a Social Security Number
It’s a simple step that can make your business appear more professional and keep your financial records cleaner.
How to Apply for an EIN
Getting an EIN is a straightforward process, and in most cases, it’s completely free. The IRS offers several ways to apply, but the online method is the fastest and easiest for most U.S.-based businesses.
Apply Online
The IRS website allows you to apply directly using their EIN Assistant. This is the preferred method for most applicants because it delivers an EIN immediately upon completion.
- Visit the IRS EIN Assistant
- Available Monday through Friday, from 7 a.m. to 10 p.m. Eastern Time
The application must be completed in one session (it can’t be saved and returned to later) - EIN is issued immediately after submission
This option is only available to businesses located in the U.S. or U.S. territories. The person applying must also have a valid Taxpayer Identification Number, such as a Social Security Number.
Apply by Fax or Mail
For those who prefer not to apply online or are unable to, the IRS also accepts applications by fax or mail using Form SS-4. This method takes longer but is still fairly simple.
- Fax: Submit a completed Form SS-4 to the IRS via the appropriate fax number. Processing typically takes around four business days.
- Mail: You can mail Form SS-4 to the IRS. This option usually takes up to four weeks, depending on processing times and mail delivery.
Apply by Phone (International Applicants Only)
If your business is located outside of the U.S. or its territories, you can apply for an EIN by calling the IRS directly. This is the only phone-based application method available.
- Call the IRS at (267) 941-1099
- The agent will ask questions from Form SS-4 and issue your EIN during the call
What You’ll Need to Apply
Before you start the application, make sure you have the required information ready. This will help you complete the process without delays.
- Legal name of the business
- Responsible party’s name and SSN or ITIN
- Business structure (LLC, corporation, sole proprietorship, etc.)
- Reason for applying (starting a business, hiring employees, banking needs, etc.)
- Mailing address and contact information
Once your EIN is assigned, it becomes the permanent federal tax ID for your business. Be sure to save the confirmation notice or download a copy immediately if applying online—you’ll need it for banking, licensing, and tax purposes.
How to Find Your EIN
If you’ve already received an EIN but misplaced the number, there are several ways to retrieve it:
- Check the original IRS confirmation letter (Form CP 575)
- Look at past tax returns, business licenses, or bank account documents
- Contact your bank if you used your EIN when opening a business account
- Call the IRS Business & Specialty Tax Line at (800) 829-4933 for assistance
Keep in mind that the IRS will only provide EIN information to an authorized person associated with the business.
When You Might Need a New EIN
In most cases, an EIN is permanent and stays with your business for the life of the entity. However, there are certain situations where the IRS requires you to apply for a new one. These typically involve major changes to the structure or ownership of your business.
Changes in Business Structure
If you significantly change the legal structure of your business, you’ll likely need a new EIN. Examples include:
- You incorporate a sole proprietorship or form an LLC
- You change from a sole proprietorship to a partnership (or vice versa)
- Your business merges with another or becomes part of a new entity
These structural changes create a new legal identity in the eyes of the IRS, which means your old EIN may no longer apply.
Changes in Ownership
Ownership changes alone don’t always require a new EIN, but they can in certain cases. For example:
- A sole proprietorship is sold to another person
- A partnership has a complete change in partners
- A corporation becomes a subsidiary or undergoes reorganization
In these scenarios, the IRS considers the original entity to have ended, and a new EIN is needed for the new ownership structure.
Other Situations That Require a New EIN
In addition to structural and ownership changes, other events may trigger the need for a new EIN:
- You start a new business that is legally separate from your current one
- You receive a new charter from your state or a different state
- You establish a trust, estate, or nonprofit that operates independently
If you’re unsure whether a change requires a new EIN, the IRS provides detailed guidance on its website, or you can consult a tax professional.
Frequently Asked Questions About EINs
If you apply online through the IRS EIN Assistant, you’ll receive your EIN immediately after completing the application. Fax applications usually take about four business days, while mail-in applications can take up to four weeks. International applicants applying by phone can also receive their EIN during the call.
Start by checking your EIN confirmation letter or any official documents where the number may be recorded, such as tax filings or bank paperwork. If you can’t find it, you can call the IRS Business & Specialty Tax Line at (800) 829-4933. They’ll verify your identity and help you recover your EIN.
Not exactly. An EIN is a type of Taxpayer Identification Number (TIN) used for businesses. FEIN—short for Federal Employer Identification Number—is simply another name for an EIN. These terms are often used interchangeably, but TIN is a broader term that can also refer to Social Security Numbers and other identifiers.
Not necessarily. If you keep the same business structure and ownership, moving your business to a new state does not usually require a new EIN. However, if your move involves reorganizing or reestablishing the entity under a new charter, you may need to apply for a new one.