Employer Identification Number (EIN): The Complete Guide for US Business Owners

An Employer Identification Number (EIN) is a free, nine-digit federal tax ID (formatted 12-3456789) that the IRS assigns to your business so it can be identified for tax, payroll, and banking purposes — think of it as a Social Security Number for your company. You apply directly through the IRS, most owners receive the number the same day online, and there is never a fee. You need one if your business hires employees, operates as a corporation or partnership, files certain excise or employment taxes, or simply wants to open a business bank account and build a credit profile separate from your personal one. Below we cover exactly who is required to have an EIN, how to apply step by step, the mistakes that cost owners time, and — from an underwriter's chair — how your EIN and the business banking behind it actually influence a funding decision.

What an EIN Is and What It Is Not

An EIN — also called a Federal Employer Identification Number (FEIN) or Federal Tax ID Number — is issued by the IRS and stays attached to your business entity for its lifetime. It does not expire, it is not reused for another business even after yours closes, and it is not something you renew annually.

It is easy to confuse an EIN with related numbers, so keep these distinct:

• EIN vs. SSN: Your Social Security Number identifies you as an individual; the EIN identifies the business. Using an EIN on business accounts is the first step in separating personal and business finances.
• EIN vs. ITIN: An Individual Taxpayer Identification Number is for people who need a tax ID but are not eligible for an SSN. It is a personal number, not a business one — though the IRS lets a "responsible party" with an ITIN apply for an EIN.
• EIN vs. state tax ID: Many states issue their own tax or employer registration numbers for state income tax, sales tax, or unemployment insurance. A state ID does not replace the federal EIN; most employers need both.
• EIN vs. DUNS number: A DUNS number (now the UEI in federal contracting) is a commercial identifier from Dun & Bradstreet used for business credit reporting and government contracts. It is separate from — and does not substitute for — an EIN.

Who Is Required to Have an EIN

The IRS requires an EIN in specific situations. You must obtain one if any of the following is true:

• You have or plan to hire employees (including household employees in some cases).
• Your business is a corporation (C-corp or S-corp) or a partnership, regardless of whether it has employees.
• You file employment, excise, or alcohol/tobacco/firearms tax returns.
• You withhold taxes on income (other than wages) paid to a non-resident alien.
• You have a Keogh plan or certain retirement/trust arrangements.
• Your business is involved with trusts, estates, non-profits, farmers' cooperatives, or plan administrators.

Sole proprietors and single-member LLCs with no employees are the common exception: they are technically allowed to use the owner's SSN. But most still get an EIN voluntarily, because banks, payment processors, and funders increasingly expect one — and because using an EIN keeps your SSN off vendor and lender paperwork, reducing identity-theft exposure. For an operator planning to grow, applying early is the low-friction move.

How to Apply for an EIN, Step by Step

The application is free and, done correctly, takes about 10-15 minutes. Apply directly with the IRS — never pay a third-party site that charges a "processing fee" for something the government provides at no cost.

1. Confirm eligibility. Your business must be located in the US or a US territory, and the responsible party must have a valid taxpayer ID (SSN, ITIN, or existing EIN).
2. Choose your responsible party. This is the individual who ultimately controls or owns the business. The IRS wants a real person here, not another entity, in most cases.
3. Gather your details. Legal business name, entity type, formation date, state, mailing address, and the reason you're applying (e.g., started a new business, hired employees, banking purposes).
4. Apply through the right channel:
   • Online (fastest): The IRS online assistant issues the EIN immediately on completion. The session must be finished in one sitting and is available during posted hours.
   • Fax: Submit Form SS-4; expect roughly four business days.
   • Mail: Form SS-4 by mail can take about four weeks.
   • International applicants without an SSN/ITIN can apply by phone.
5. Save your CP 575 confirmation letter. This is the official notice confirming your EIN. Store it securely — banks and funders may ask to see it.

One EIN per responsible party per day is the IRS limit for online applications, so plan accordingly if you are forming multiple entities.

Realistic Example: EIN's Role in Three Funding Scenarios

An EIN by itself does not get you approved. What it does is anchor the business identity and the business bank account that revenue-based funders actually underwrite. The figures below are illustrative — provided "for example" to show how the same EIN produces very different outcomes depending on the deposit history behind it.

The lesson: get the EIN early, open a dedicated business account under it immediately, and run your revenue through that account. The deposit trail you build is the asset a funder evaluates — the EIN just makes it legible.

How Funders Actually Use Your EIN in Underwriting

From an underwriter's perspective, the EIN is a verification tool, not an approval trigger. Here is what happens behind the scenes when you apply for revenue-based financing or a merchant cash advance through a marketplace:

• Identity and legitimacy check: The EIN confirms the business is a registered entity and matches the name on your bank statements and application.
• Business credit pull (sometimes): Revenue-based funders lean far more on bank deposits and cash flow than on credit. Many will work with a FICO of 500 or higher because the decision is driven by the money moving through your account, not a credit score.
• Bank statement matching: The name and EIN tie your submitted statements to the entity, which is how underwriters confirm the revenue is really yours.
• Fraud and duplicate-application screening: The EIN helps flag stacking or mismatched identities.

For qualified businesses, a marketplace can turn around a decision in roughly 24-48 hours on funding amounts starting around $10,000, with approval built on your revenue and deposit consistency rather than perfect credit. No legitimate funder can "guarantee" approval — anyone who does is a warning sign. To understand the product itself, see our revenue-based financing guide and our overview of business funding requirements.

Decision Framework: When Getting an EIN Now Helps — and When to Wait

You will never be penalized for getting an EIN, but the strategic timing around it matters, especially if funding is on your horizon.

Getting an EIN now works best when:

• You are forming an LLC, corporation, or partnership — you'll need it regardless.
• You are about to hire your first employee or set up payroll.
• You want to open a business bank account and start building a clean, fundable deposit history.
• You want to keep your SSN off vendor, processor, and lender paperwork.
• You plan to apply for funding within the next 6-12 months and need runway to build deposits under the entity.

An EIN alone won't solve your problem when:

• You expect the EIN itself to unlock financing — it won't. Funders underwrite the revenue behind it, not the number.
• You just opened the business account this week — there is no deposit history yet for a revenue-based funder to evaluate. Build three to six months first.
• Your revenue is still flowing through a personal account — commingled funds make underwriting harder. Separate them before applying.
• You are shopping for "EIN-only, no-SSN" funding to avoid a personal guarantee — most small-business financing still involves a personal guarantee, and "no credit check" offers deserve heavy scrutiny.

Bottom line: get the EIN early so the business identity and bank account are in place, then let the deposit history mature. The EIN is the foundation; cash flow is what gets funded.

Managing, Updating, and Protecting Your EIN

Once issued, an EIN needs light but real maintenance:

• Changing business info: If your business name or address changes, notify the IRS (name changes are typically handled on your tax return or by written notice; address changes use Form 8822-B). The EIN itself stays the same.
• When you need a new EIN: A change in entity structure — for instance, a sole proprietorship incorporating, or a partnership converting to a corporation — usually requires a new EIN. A simple name or location change does not.
• Closing a business: The IRS never reassigns your EIN, but you should send a letter to close the business account associated with it after filing final returns.
• If you lose it: Check your CP 575 letter, a prior tax return, old bank paperwork, or call the IRS Business & Specialty Tax Line to retrieve it.
• Protect it: Treat your EIN like sensitive data. It's less secret than an SSN, but exposure can enable business identity theft and fraudulent credit applications. Share it only with parties who legitimately need it — your bank, payroll provider, accountant, and funders you've chosen to work with.