An EIN and a W-9 are not alternatives; they work together. An EIN (Employer Identification Number) is a nine-digit tax ID number the IRS assigns to a business. A W-9 is the IRS form a business uses to collect a payee’s tax ID number, which can be an EIN or a Social Security Number depending on the payee. So when people compare EIN vs. W-9, the real question is usually which tax ID belongs on the W-9 — and whether a business needs an EIN at all before filling one out.
Here is how each piece fits.
What an EIN Is and Who Needs One
An Employer Identification Number is the federal tax ID for a business entity, functioning the same way a Social Security Number identifies an individual.1Internal Revenue Service. Publication 1635 – Understanding Your EIN Businesses use it on tax returns, information filings, and payroll documents.
Some entities have no choice about getting one:
- All corporations and all partnerships.
- Multi-member LLCs, because the IRS taxes them as either a partnership or a corporation.
- Any business with employees, including a sole proprietorship or single-member LLC that hires even one person, so payroll taxes can be reported.2Internal Revenue Service. Employer Identification Number
A sole proprietor with no employees can skip the EIN and report business income on Schedule C using just an SSN. Many still choose to get one anyway, to avoid handing an SSN to every client that sends a W-9. The IRS issues EINs for free, so the privacy benefit costs nothing. The IRS does note that an EIN is meant for business activities and shouldn’t replace an SSN for personal matters.1Internal Revenue Service. Publication 1635 – Understanding Your EIN
What a W-9 Is and What It Collects
Form W-9, “Request for Taxpayer Identification Number and Certification,” is the form a business gives to a payee — typically a contractor or vendor — to collect their tax identification information.3Internal Revenue Service. About Form W-9, Request for Taxpayer Identification Number and Certification The payee fills it out and returns it to the business. It does not go to the IRS. It stays in the payer’s files as the source document behind any 1099 forms the payer files at year-end.
The W-9 captures three things. First, the payee’s legal name, any business or trade name, and a checked box for federal tax classification (sole proprietor, partnership, C corporation, S corporation, trust, or LLC with its elected tax treatment). Second, the payee’s Taxpayer Identification Number (TIN), which can be an SSN, an ITIN, or an EIN. Third, a signed certification under penalties of perjury that the TIN is correct, the payee is not subject to backup withholding, the payee is a U.S. person, and any FATCA exemption code is accurate.4Internal Revenue Service. Form W-9 (Rev. March 2024)
By signing, the payee takes legal responsibility for the accuracy of the information. If the IRS later finds errors, the trail leads back to that signed W-9.
Which Number Goes on the W-9
The right number in the TIN box depends on how the IRS classifies your business.
Corporations, partnerships, and multi-member LLCs always enter their EIN. These entities are separate taxpayers in the eyes of the IRS, so the entity’s own number is the only correct choice.2Internal Revenue Service. Employer Identification Number
Sole proprietors can enter either an SSN or an EIN if they have one. The income flows to the individual’s Form 1040 either way.
The Single-Member LLC Trap
A single-member LLC is treated as a “disregarded entity” by default, meaning the IRS ignores the LLC wrapper and taxes the income directly to the owner. On the W-9, the owner’s name goes on line 1 and the LLC’s name goes on line 2. The TIN should be the owner’s SSN or the owner’s EIN, not a separate EIN issued in the LLC’s name alone.5Internal Revenue Service. Instructions for the Requester of Form W-9 (03/2024)
The exception is a single-member LLC that has elected to be taxed as a corporation. Once that election is in place, the LLC is no longer disregarded. It needs its own EIN, that EIN goes in the TIN box, and the entity-type checkbox must reflect the corporate election. When the box says “LLC taxed as a C corporation” but the TIN belongs to an individual, the name and number won’t match in the IRS system, which triggers a CP2100 or CP2100A mismatch notice to the payer.6Internal Revenue Service. Understanding Your CP2100 or CP2100A Notice
When You’d Use a W-8 Instead
The W-9 is only for U.S. persons. If you’re paying a contractor or vendor who isn’t a U.S. citizen or resident, the W-9 is the wrong form. Foreign individuals fill out Form W-8BEN, whether or not they’re claiming a reduced withholding rate under a tax treaty.7Internal Revenue Service. About Form W-8 BEN, Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting (Individuals) Foreign entities such as companies or partnerships organized outside the U.S. use Form W-8BEN-E.8Internal Revenue Service. About Form W-8 BEN-E, Certificate of Status of Beneficial Owner for United States Tax Withholding and Reporting (Entities)
If neither form is on file, the default assumption is that the payee is foreign and subject to withholding, which creates an obligation to withhold tax from every payment.5Internal Revenue Service. Instructions for the Requester of Form W-9 (03/2024)
How to Get an EIN
The IRS issues EINs for free, and online is the fastest route. The application takes minutes, and the number is assigned at the end.2Internal Revenue Service. Employer Identification Number
To apply online you need a principal place of business in the United States or a U.S. territory and a valid SSN or ITIN for the responsible party. The system walks you through selecting entity type, entering the legal name and address, and identifying that person. You’re limited to one EIN application per day, whether online, by phone, by fax, or by mail.2Internal Revenue Service. Employer Identification Number
One timing detail catches people off guard. You can use a new EIN right away for most purposes, such as opening a bank account or filing a paper return, but you’ll need to wait about two weeks before the number works in the IRS TIN Matching system or for e-filing.2Internal Revenue Service. Employer Identification Number Plan ahead if you’re forming an entity close to a filing deadline.
What Happens If the W-9 Is Wrong or Missing
This is where getting the EIN vs. SSN question right on the W-9 actually matters. If a payee doesn’t provide a TIN, provides an incorrect one, or fails to certify they’re not subject to backup withholding, the payer must withhold 24% of every reportable payment and deposit that amount with the IRS.9Internal Revenue Service. Backup Withholding The withholding continues until the payee fixes the problem. If the payer doesn’t withhold when required, the payer becomes personally liable for the uncollected amount.5Internal Revenue Service. Instructions for the Requester of Form W-9 (03/2024)
Filing an incorrect information return, including one with a wrong or missing TIN, also carries a penalty of $340 per return for filings due in 2026. It drops to $60 if corrected within 30 days of the due date, or $130 if corrected before August 1. Intentional disregard of the filing requirement raises the penalty to $680 per return with no annual cap.10Internal Revenue Service. Information Return Penalties
When the IRS detects a name-and-TIN mismatch, it sends the payer a CP2100 notice (for 50 or more errors) or a CP2100A notice (for fewer than 50). The payer then has to contact the payee, request a corrected TIN, and begin backup withholding if the payee doesn’t respond.6Internal Revenue Service. Understanding Your CP2100 or CP2100A Notice Collecting a clean W-9 up front, with the right TIN for the payee’s entity type, is what keeps that whole chain from starting.