EIN Number: The Complete Guide for Small Business Owners

Did you know that every month nearly half a million new business applications are filed in the United States—each one tied to an Employer Identification Number? Yet many small business owners don't fully understand what an EIN is, when they need one, or how to use it correctly. Getting this nine-digit number wrong can cause delays with the IRS, problems opening bank accounts, and even identity theft risks.

This guide covers everything you need to know about EINs: what they are, who needs one, how to get one for free, and the common mistakes that trip up business owners.

What Is an EIN?

An EIN (Employer Identification Number), also called a Federal Employer Identification Number (FEIN), is a unique nine-digit number assigned by the IRS to identify your business entity for tax purposes. It follows the format XX-XXXXXXX.

Think of it as a Social Security number for your business. Just as your SSN identifies you as an individual taxpayer, your EIN identifies your business when you file taxes, open bank accounts, hire employees, or apply for business credit.

The IRS uses EINs to track:

• Business tax filings and payments
• Employment tax obligations
• Excise tax returns
• Other business-related reporting requirements

Who Needs an EIN?

You are legally required to obtain an EIN if your business meets any of these criteria:

• Has employees — Any business that pays wages must have an EIN for payroll tax purposes
• Operates as a corporation — C corporations and S corporations must have an EIN
• Operates as an LLC — Most LLCs need an EIN, especially multi-member LLCs
• Operates as a partnership — All partnerships must have an EIN
• Files employment or excise taxes — These returns require an EIN regardless of business structure
• Withholds taxes on non-wage income — Such as certain payments to foreign persons
• Has a Keogh plan or solo 401(k) — Retirement plans require an EIN
• Acquired an existing business through purchase or inheritance
• Filed for bankruptcy

What About Sole Proprietors?

Sole proprietors are the one exception. You can legally use your Social Security number for business tax filings if you have no employees. However, getting an EIN is strongly recommended even if you aren't required to have one. Here's why:

Identity protection: Every time you hand over a W-9 to a client, you expose your SSN. With an EIN, you share your business identifier instead, significantly reducing your identity theft risk.

Banking: Most banks require an EIN to open a dedicated business checking account.

Business credit: Lenders and credit bureaus use EINs to build a credit profile for your business, separate from your personal credit.

Future growth: If you ever hire employees, you'll need an EIN anyway. Getting one now saves administrative friction later.

The EIN is free and takes minutes to obtain — there's no good reason to delay.

How to Get an EIN: Step-by-Step

Method 1: Apply Online (Recommended)

The IRS offers an online EIN application at IRS.gov that issues your EIN immediately upon completion.

Requirements:

• A Social Security number or ITIN for the "responsible party" (the person who controls the business)
• Basic business information: legal name, address, business structure, reason for applying

Important limitations:

• The online application is only available Monday through Friday, 7 a.m. to 10 p.m. Eastern time
• You must complete it in a single session — the system times out and does not save progress
• Only one EIN may be issued per responsible party per day

Timeline: Immediate — you receive your EIN as soon as you submit the application.

Method 2: Apply by Fax

Download IRS Form SS-4, complete it, and fax it to the IRS. You'll receive your EIN by fax within four business days.

Method 3: Apply by Mail

Mail your completed Form SS-4 to the IRS. Processing takes four to five weeks — avoid this method unless fax or online options aren't available to you.

Method 4: Apply by Phone (International Applicants)

Business owners outside the U.S. can apply by calling the IRS International Applicant line. The IRS will issue the EIN during the call.

Cost: Free. The IRS never charges for an EIN. If a website asks you to pay for an EIN application, it is a third-party service, not the IRS itself.

When You Need a New EIN

Many business owners assume their EIN is permanent. In most cases it is — but certain structural changes require you to obtain a new one.

Sole Proprietors Must Get a New EIN When:

• Incorporating the business
• Taking on partners and operating as a partnership
• Purchasing or inheriting an existing business
• Filing for bankruptcy under Chapter 7 or Chapter 11

Partnerships Must Get a New EIN When:

• Incorporating
• The partnership is taken over by a single partner and becomes a sole proprietorship
• Ending the existing partnership and forming a new one

Corporations and LLCs Must Get a New EIN When:

• Changing the business structure (e.g., LLC electing S-corp status)
• There is a change in ownership that creates a new legal entity

When You Do NOT Need a New EIN:

• Changing your business name
• Moving to a new location
• Adding a DBA (doing business as) name
• Opening additional locations under the same legal entity
• Hiring your first employee (if you already have an EIN)

If you're unsure whether your situation requires a new EIN, consult the IRS guidelines or speak with a tax professional before applying. Getting an unnecessary second EIN can create confusion on your tax filings.

EIN vs. State Tax ID: What's the Difference?

Your federal EIN is issued by the IRS and works nationwide. However, many states require a separate State Tax ID (sometimes called a State EIN) for state-level tax obligations.

State Tax IDs are required for:

• Collecting and remitting state sales tax
• Filing state payroll taxes
• Meeting state employment requirements

If you operate in multiple states, you may need a separate State Tax ID for each state where you have employees or nexus. Formats and fees vary by state — contact your state's department of revenue to determine what's required.

Seven states have no income tax, but most businesses still need a State Tax ID for sales tax purposes regardless.

Common EIN Mistakes to Avoid

1. Using the Wrong Legal Name

The IRS matches your EIN application with your business name exactly as registered. A mismatch between your EIN application and your tax returns or W-2s causes processing delays and potential rejections. Use your exact legal business name — not a DBA.

2. Applying Before State Registration

Many states require you to register your business entity before applying for a federal EIN. Applying beforehand can result in an EIN that doesn't match your state registration, creating compliance issues.

3. Using One EIN for Multiple Legal Entities

Each legal entity needs its own EIN. Operating multiple businesses under a single EIN — even if they share the same owner — creates financial reporting inconsistencies and can complicate your taxes.

4. Not Protecting Your EIN

Treat your EIN like sensitive personal information. If stolen, it can be used to fraudulently file tax returns or open lines of credit in your business name. Store it securely and share it only when necessary.

5. Incorrect EIN on Tax Payments

Payments submitted with an incorrect EIN can be placed in suspense by the IRS for months, triggering penalties and interest even though you made the payment. Always double-check your EIN before submitting tax payments.

6. Failing to Update the IRS After Structural Changes

If you change your business structure without obtaining the correct new EIN, your filings won't match IRS records. This creates headaches that can take significant time to untangle.

What to Do If You Lose Your EIN

Losing your EIN doesn't mean starting over. Here's how to recover it:

1. Check your original confirmation letter — The IRS sends an EIN confirmation (CP 575) when you first apply. If you have it, your EIN is on there.
2. Check old tax returns — Your EIN appears on every business tax return you've filed.
3. Check your bank — If you opened a business bank account with your EIN, the bank has it on file.
4. Call the IRS — The IRS Business & Specialty Tax Line (800-829-4933) can verify your EIN if you are the authorized representative of the business.

EIN FAQs

Can I apply for an EIN if I'm not yet open for business? Yes. Many businesses apply for an EIN during the formation process, before officially launching. This lets you open bank accounts and handle pre-launch financial activity properly.

Does an EIN expire? No. Once issued, an EIN is permanent. It stays with the business entity even if the business goes dormant for years.

Can a non-U.S. citizen get an EIN? Yes, though the process is different. International applicants without an SSN or ITIN must apply by phone or submit Form SS-4 by fax or mail with supporting documentation.

Is an EIN the same as a TIN? An EIN is a type of Taxpayer Identification Number (TIN). The broader TIN category also includes SSNs, ITINs, and Adoption Taxpayer Identification Numbers. When businesses refer to their TIN, they typically mean their EIN.

Do I need an EIN for a single-member LLC? If you have no employees and haven't elected corporate tax treatment, you can use your SSN. However, getting an EIN is strongly recommended for the identity protection and banking benefits described above.

Keep Your Business Finances Organized from Day One

Getting your EIN is the first step in establishing a financial identity for your business — but it's just the beginning. From that moment on, accurate bookkeeping is what keeps your business on solid footing and makes tax time manageable.

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