Business Formation · 2026-04-13

What Is an EIN? Why Your LLC Needs One and How It Works

An EIN is your LLC\

Your Company's Identity Number

An Employer Identification Number (EIN) is a nine-digit number issued by the IRS that uniquely identifies your business entity for tax purposes. Think of it as your company's Social Security number — except it's tied to the LLC itself, not to you personally.

Every LLC that plans to open a bank account, file taxes, hire employees, or transact on major platforms needs an EIN. It's free to obtain, it never expires, and once issued, it stays with your LLC permanently.

The format looks like this: XX-XXXXXXX (two digits, a hyphen, then seven digits).

Where Your EIN Gets Used

Your EIN shows up in more places than most founders expect:

**Bank account opening** — Every US bank requires an EIN to open a business account. No EIN, no account. See our [complete guide to opening a US bank account with a Wyoming LLC](/blog/us-bank-account-wyoming-llc-guide-2026).

**IRS tax filing** — Your annual tax return (Form 1065 for partnerships, 1120 for corporations, or Schedule C for single-member LLCs) is filed under your EIN.

**Amazon Seller Central** — Amazon requires an EIN during seller identity verification. Without it, your application stalls.

**Stripe** — Stripe's onboarding flow asks for your EIN to verify your business entity. A mismatch between your EIN records and your Stripe application triggers manual review.

**Hiring employees or contractors** — W-2s and 1099s are issued under your EIN.

**State tax registrations** — Sales tax permits, payroll tax accounts, and state business registrations reference your EIN.

**Vendor and wholesale accounts** — Many suppliers require an EIN on their credit application forms.

If your LLC will interact with the US financial system in any meaningful way, you need an EIN.

EIN vs. SSN vs. ITIN: What's the Difference?

These three numbers serve different purposes and are not interchangeable:

| | EIN | SSN | ITIN |

|---|---|---|---|

| Issuing agency | IRS | Social Security Administration | IRS |

Key point for international founders: You do not need an SSN or ITIN to get an EIN for your LLC. The application process is different (fax/mail instead of online), but the EIN itself functions identically regardless of how you obtained it.

How International Founders Get an EIN

This is where most guides oversimplify. The process depends on whether you have an SSN or ITIN.

If You Have an SSN or ITIN

You can apply online at irs.gov and receive your EIN immediately — the process takes about 10 minutes. You'll get a confirmation notice (CP 575) mailed to the address on your application.

If You Don't Have an SSN or ITIN (Most International Founders)

The IRS online application requires an SSN or ITIN as the "responsible party" identifier. Without one, you must apply by fax or mail using Form SS-4.

The fax method (recommended):

1. Complete IRS Form SS-4. In the "responsible party" section, enter your name and foreign passport number.

2. Fax the completed form to the IRS at (855) 641-6935 (for applicants outside the US) or (859) 669-5760 (domestic fax).

3. Wait 4-6 weeks for the IRS to process your application.

4. The IRS will fax back your EIN assignment notice, or mail the CP 575 letter to the address you provided on the SS-4.

The mail method:

Same form, mailed to: Internal Revenue Service, Attn: EIN International Operation, Cincinnati, OH 45999. Processing time is similar — 4 to 6 weeks, sometimes longer.

Important: Some founders try to call the IRS Business Tax Line to get an EIN over the phone. This technically works but requires calling during US business hours, navigating hold times, and verbally providing your information to an agent. The fax method is more reliable.

For a deeper dive into the address requirements for your SS-4, see our guide to EIN application address requirements for non-residents.

The Address on Your SS-4 Matters

This is the detail that trips up the most founders.

The address you put on Form SS-4 becomes your IRS address of record. This is the address where the IRS will:

Mail your CP 575 EIN confirmation letter

Send all future IRS correspondence (notices, audit letters, tax forms)

Associate with your EIN in their database

When you later open a bank account, the bank may cross-reference your EIN with IRS records. If the address on your bank application doesn't match what the IRS has on file, it raises a flag during KYB verification.

Best practice: Use the same physical business address on your SS-4 that you plan to use for banking, state filings, and platform registrations. Address consistency across all documents is one of the strongest signals of a legitimate business. If you're forming a Wyoming LLC, read our guide for non-US founders to understand how all these pieces fit together.

Common Mistakes That Cause Problems

Using a Registered Agent Address on the SS-4

Your registered agent's address is for receiving legal service of process — not for general business use. Putting an RA address on your SS-4 means:

The IRS mails your CP 575 to the RA, who may not forward it promptly (or at all)

Your IRS address of record becomes an address shared by hundreds of other entities

Banks see the RA address on your EIN records and flag it during verification

Use your actual business operating address on the SS-4. This should be the same address on your Articles of Organization and your bank application.

Losing the CP 575 Confirmation Letter

The CP 575 is the original EIN assignment letter from the IRS. Banks, payment processors, and government agencies sometimes specifically request this document — not a printout from the IRS website, not a screenshot, but the actual CP 575 notice.

If you lose it, you can request a replacement called a 147C letter by calling the IRS. But this requires another phone call during US business hours and can take weeks to arrive by mail.

Save your CP 575 immediately. Scan it, store it digitally, and keep the original in a safe place. You will need it for bank applications and KYB document reviews.

Filing the SS-4 with Inconsistent Information

The name on your SS-4 must exactly match your Articles of Organization. "My Company LLC" and "My Company, LLC" (with a comma) are treated as different entities by some systems. The address format should also be consistent — use the exact same format across all filings.

After You Receive Your EIN

Once you have your EIN, a few things to keep in mind:

1. It's permanent. Your EIN stays with your LLC forever, even if you change members, managers, or addresses. You only need a new EIN if the entity structure changes (e.g., an LLC converts to a corporation).

2. Update your address with the IRS if you move. File Form 8822-B to change your business address on IRS records. This keeps your bank records and IRS records in sync.

3. Keep the CP 575 accessible. You'll need it for bank account opening, Amazon seller verification, Stripe onboarding, and potentially state registrations. See our bank KYB checklist for the full list of documents banks request.

4. Your EIN is not secret, but don't broadcast it. Unlike an SSN, an EIN is semi-public (it appears on tax filings shared with partners, vendors, and employees). But there's no reason to post it publicly.