How to Fill Out a W-9 for an LLC: Classification, TIN, and Signature

Filling out a W-9 for an LLC turns on one question the form never asks directly: how does the IRS tax your LLC? State law made your business an LLC, but the IRS files it under one of four federal tax categories, and that category controls the name you write on Line 1, the box you check on Line 3, and the taxpayer identification number you put in Part I. Get the combination wrong and you create a name-and-TIN mismatch that triggers backup withholding at 24% of every payment until you fix it.¹

Start With Your Federal Tax Classification

Before you fill in a single field, figure out which of these four buckets your LLC falls into. Check your last federal return or your IRS correspondence if you’re not sure.

Single-member LLC treated as a disregarded entity. One owner, no election filed to change tax treatment. The IRS treats the LLC as if it didn’t exist for income tax purposes, and the business income lands on the owner’s personal return, usually Schedule C.²

Multi-member LLC taxed as a partnership. Two or more owners, no corporate election. The LLC files Form 1065 as an informational return, and each owner gets a Schedule K-1.³

LLC taxed as an S corporation or C corporation. The LLC filed Form 2553 to elect S corporation status, or Form 8832 to elect C corporation status.⁴ Under either election, the LLC itself is the taxpayer.

Lines 1 and 2: Which Name Goes Where

The name on Line 1 must match the TIN in Part I. That pairing is what the IRS checks automatically, and a mismatch is what generates a CP2100 notice and backup withholding. So Line 1 belongs to whichever person or entity is the taxpayer, and that depends on classification.

Disregarded Entity

If your single-member LLC is a disregarded entity owned by you individually, Line 1 gets your personal legal name exactly as it appears on your tax return. Line 2 gets the LLC’s legal name.⁵ This feels backward, but you are the taxpayer, not the LLC.

When another business owns the disregarded LLC, the same logic applies: the parent entity goes on Line 1, and the disregarded LLC’s name goes on Line 2.²

Partnership or Corporation

If your LLC is taxed as a partnership, S corporation, or C corporation, Line 1 gets the LLC’s full legal name as registered with the state. The LLC is the taxpayer. Line 2 is only for a separate trade name or DBA, and most LLCs in this group leave it blank.

Line 3a: The Classification Box

Line 3a on the current form (Rev. March 2024) gives you seven boxes: Individual/sole proprietor, C corporation, S corporation, Partnership, Trust/estate, LLC, and Other.⁶ Which one you check is the single most common source of error.

A disregarded entity owned by an individual checks Individual/sole proprietor. Do not check the LLC box. The IRS instructions direct disregarded entities to check the box that matches the owner’s classification, not the LLC’s legal form.⁵ If the disregarded entity is owned by a corporation, check the C corporation or S corporation box to match the parent.

An LLC taxed as a partnership, S corporation, or C corporation checks the LLC box and writes a letter code in the space next to it: P for partnership, C for C corporation, or S for S corporation.⁶ The checkbox alone isn’t enough. You need both.

Line 3b: Foreign-Owner Flag

Line 3b applies only to LLCs taxed as partnerships that have foreign partners or owners and are providing a W-9 to another flow-through entity in which they hold an interest.⁷ A domestic LLC with only U.S. owners leaves it blank.

Line 4: Exemption Codes

Line 4 has two small fields, one for an exempt payee code and one for a FATCA reporting exemption code. Most LLCs leave both blank. Exempt payee codes cover entities like corporations (code 5), tax-exempt organizations, government entities, securities dealers, and financial institutions.⁶ An LLC taxed as a partnership, or a disregarded entity owned by an individual, does not qualify as an exempt payee for backup withholding. FATCA codes come up mainly when a foreign financial institution is involved, so a typical small LLC paying domestic clients or vendors will never enter anything on Line 4.

Lines 5 Through 7: Address and Account Number

Lines 5 and 6 collect the mailing address where the payer should send tax correspondence, including 1099 forms. For a disregarded entity, that’s usually the individual owner’s address. For an LLC taxed as a partnership or corporation, use the business address on file with the IRS.

Line 7 is optional. Fill it in only if the requester asks you to associate the W-9 with a specific account number on their end.

Part I: Which TIN to Use

Part I asks for one taxpayer identification number: an SSN, an EIN, or in some cases an ITIN. The TIN must belong to whoever is named on Line 1.

For a disregarded entity owned by an individual, enter your SSN. The IRS is explicit that the W-9 for a disregarded entity provides the owner’s SSN or EIN, not the LLC’s own EIN.² Your LLC may have its own EIN for payroll or state registration, but using that EIN here creates a mismatch with your personal name on Line 1. Non-citizens with federal tax obligations who aren’t eligible for an SSN use their ITIN instead.⁸

If a disregarded entity is owned by another business, use the parent entity’s EIN so it matches the parent’s name on Line 1.²

For an LLC taxed as a partnership, S corporation, or C corporation, enter the LLC’s EIN. The LLC is the taxpayer, and its EIN pairs with its name on Line 1.

Part II: Signature and Certification

Part II is a signature under penalty of perjury. You certify that the TIN is correct, that you’re not subject to backup withholding (unless the IRS has notified you otherwise), and that you’re a U.S. person. The signer must be the individual named on Line 1 or someone authorized to sign for the entity there.⁹

If the IRS has previously told you that you’re subject to backup withholding because of underreported income, cross out the certification statement about not being subject to backup withholding before you sign. Leaving it intact is a false certification.

Where the Form Goes and How to Fix a Mistake

The completed W-9 goes to the requester, not to the IRS. Because it carries your TIN, treat it as sensitive. An encrypted file-sharing platform, a password-protected PDF, or the requester’s secure upload portal is safer than a plain email attachment. If email is the only option, at least password-protect the file and share the password separately.

If you notice an error after sending, the fix is to fill out a new W-9 with the correct information and give it to the same requester. There’s no amendment form. The requester replaces the old copy with the new one. Catching the mistake before they file 1099s heads off the mismatch problem entirely. If a wrong 1099 has already gone out, the requester may get an IRS notice asking them to solicit a corrected TIN from you.⁵

What Goes Wrong When the W-9 Is Wrong

The immediate consequence is backup withholding. When the payer can’t verify your TIN or the IRS flags a mismatch, the payer withholds 24% from each payment and sends it to the IRS.¹⁰ You can claim the withheld amount as a credit when you file your return, but it sits with the IRS in the meantime.

Payers also face penalties for filing information returns with incorrect TINs. Under federal regulations, an incorrect TIN is never treated as an inconsequential error.¹¹ That penalty falls on the payer, which is why payers who receive a questionable W-9 tend to press for corrections or start withholding quickly.

Quick Reference by LLC Type

Disregarded entity, individual owner: Line 1, owner’s name. Line 2, LLC name. Line 3a, Individual/sole proprietor. Part I, owner’s SSN or ITIN.
Disregarded entity, corporate or partnership owner: Line 1, parent entity’s name. Line 2, LLC name. Line 3a, box matching the parent’s classification. Part I, parent’s EIN.
LLC taxed as a partnership: Line 1, LLC name. Line 2, DBA if any. Line 3a, LLC box with “P.” Part I, LLC’s EIN.
LLC taxed as an S corporation: Line 1, LLC name. Line 2, DBA if any. Line 3a, LLC box with “S.” Part I, LLC’s EIN.
LLC taxed as a C corporation: Line 1, LLC name. Line 2, DBA if any. Line 3a, LLC box with “C.” Part I, LLC’s EIN.

1
Internal Revenue Service. Backup Withholding
2
Internal Revenue Service. Single Member Limited Liability Companies
3
Internal Revenue Service. About Form 1065, U.S. Return of Partnership Income
4
Internal Revenue Service. About Form 2553, Election by a Small Business Corporation
5
Internal Revenue Service. Instructions for the Requester of Form W-9
6
Internal Revenue Service. Form W-9, Request for Taxpayer Identification Number and Certification
7
Internal Revenue Service. Instructions for the Requester of Form W-9
8
Internal Revenue Service. Individual Taxpayer Identification Number
9
Internal Revenue Service. Form W-9, Request for Taxpayer Identification Number and Certification
10
Internal Revenue Service. Topic No. 307, Backup Withholding
11
eCFR. 26 CFR 301.6721-1 – Failure to File Correct Information Returns