How to Fill Out a W-9 for an LLC: Line by Line by Classification

To fill out a W-9 for an LLC correctly, you first need to know how the IRS taxes your LLC, because that single fact controls your name entry, your classification box, and the taxpayer identification number you provide. State law created your LLC. The IRS ignores that and treats it as one of four things for tax purposes: a disregarded entity, a partnership, an S corporation, or a C corporation. Get the classification right and the form fills itself in. Get it wrong and you create a name-and-TIN mismatch that triggers backup withholding at 24% of every payment until it’s fixed.¹

Know Your Tax Classification Before You Start

Four possibilities, and your LLC is one of them.

A single-member LLC with no corporate election is a disregarded entity. The IRS treats it as if it doesn’t exist for income tax; your business income flows onto your personal return, usually Schedule C.² You are the taxpayer, not the LLC.

A multi-member LLC with no corporate election defaults to partnership taxation. The LLC files Form 1065 and issues each owner a Schedule K-1.³

An LLC that filed Form 2553 or Form 8832 is taxed as an S corporation or C corporation.⁴ The LLC itself is the taxpayer.

If you aren’t sure, check your IRS correspondence or your last federal return for the business. Everything below depends on this.

Lines 1 and 2: The Name Trap

The name on Line 1 must match the TIN in Part I. The IRS runs an automated check on that pairing, and a mismatch generates a CP2100 notice and backup withholding. Which name goes where depends entirely on classification.

Single-Member LLC Owned by an Individual

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 to most LLC owners, and it’s the single most common mistake on the form. The reason: you are the taxpayer, and your name has to match your SSN. The LLC name goes on Line 2 so the payer knows the business they’re actually dealing with.

Single-Member LLC Owned by Another Entity

Line 1 gets the parent entity’s name. Line 2 gets the disregarded LLC’s name. The parent is the taxpayer.²

LLC Taxed as a Partnership, S Corp, or C Corp

Line 1 gets the LLC’s full legal name as registered with the state. The LLC is the taxpayer, and its name has to match its EIN. Line 2 is only used if the LLC operates under a separate DBA. Most LLCs in this category leave Line 2 blank.

Line 3a: The Classification Box

Line 3a offers one box each for Individual/sole proprietor, C corporation, S corporation, Partnership, Trust/estate, LLC, and Other.⁶ You check exactly one.

If your LLC is a disregarded entity owned by an individual, check Individual/sole proprietor. Do not check the LLC box. The IRS instructions direct disregarded entities to check the box matching their owner’s tax classification.⁵ If a disregarded entity is owned by a corporation, you check the corporate box that matches the parent.

If your LLC is taxed as a partnership, S corp, or C corp, check the LLC box and write the letter in the space provided: P for partnership, S for S corporation, C for C corporation.⁶ You need both the checkbox and the letter. Checking the LLC box without the letter leaves the form incomplete.

Line 3b and Line 4: Usually Blank

Line 3b applies only to partnership-taxed LLCs that have foreign partners and that are providing the W-9 to another flow-through entity. Domestic LLCs with only U.S. owners can ignore it.⁷

Line 4 has two subfields: an exempt payee code and a FATCA reporting exemption code. Both apply to narrow categories of entities. An LLC taxed as a C corporation can enter code 5 (corporations) to claim exemption from backup withholding on most payment types. Other exempt payees include 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.

The FATCA code field matters mainly when a foreign financial institution is involved. A typical small LLC paying domestic vendors leaves both fields blank.

Lines 5 Through 7: Address and Account Number

Lines 5 and 6 take your mailing address, city, state, and ZIP. Use the address where you want the payer to send tax correspondence and 1099s. For a disregarded entity, that’s usually the individual owner’s address. For a partnership or corporate-taxed LLC, use the business address on file with the IRS.

Line 7 is optional. A requester might ask you to enter an account number so they can match the W-9 to a specific account on their end. If they haven’t asked, leave it blank.

Part I: Taxpayer Identification Number

The TIN must belong to the person or entity named on Line 1. That’s the rule, and it’s where the single-member LLC trap closes.

If your LLC is a disregarded entity owned by you as an individual, enter your SSN. The IRS is explicit: use the owner’s SSN or EIN, not the LLC’s own EIN.² If your LLC has its own EIN for payroll or state registration, putting that EIN on the W-9 creates a mismatch with your name on Line 1 and sets off the backup-withholding cascade. If you’re a non-citizen ineligible for an SSN but with federal tax obligations, use your ITIN.⁸

If your LLC is a disregarded entity owned by another business, enter the parent’s EIN.

If your LLC is taxed as a partnership, S corporation, or C corporation, enter the LLC’s EIN.

Part II: Certification and Signature

You sign under penalty of perjury that the TIN is correct, that you aren’t subject to backup withholding, and that you’re a U.S. person. The signer must be the person named on Line 1 or someone authorized to sign for the entity on Line 1.⁹

One exception matters: if the IRS has notified you that you’re subject to backup withholding because of underreported interest or dividend income, you must cross out item 2 in the certification before signing. Leaving it intact when you’ve received that notice is a false certification.

Electronic signatures are valid when the requester’s system authenticates the signer and includes the perjury statement from the paper form.⁵

Quick Reference by LLC Type

Single-member LLC, individual owner (disregarded entity): Line 1 your name, Line 2 LLC name, Line 3a check Individual/sole proprietor, Part I your SSN or ITIN.
Single-member LLC, entity owner (disregarded entity): Line 1 parent entity name, Line 2 LLC name, Line 3a check the box matching the parent’s classification, Part I parent’s EIN.
Multi-member LLC (partnership): Line 1 LLC name, Line 2 DBA if any, Line 3a check LLC and write P, Part I LLC’s EIN.
LLC taxed as S corporation: Line 1 LLC name, Line 2 DBA if any, Line 3a check LLC and write S, Part I LLC’s EIN.
LLC taxed as C corporation: Line 1 LLC name, Line 2 DBA if any, Line 3a check LLC and write C, Part I LLC’s EIN.

Where to Send It and How to Send It Safely

A completed W-9 goes to the requester, never to the IRS. The requester keeps it in their records and uses it to issue 1099s.

Because the form has your TIN on it, treat it like any document carrying sensitive personal data. Avoid plain email attachments. Encrypted file sharing, password-protected PDFs, or the requester’s own secure upload portal are safer options. If a requester insists on email, password-protect the file and send the password through a separate channel.

Fixing a Mistake After You’ve Sent It

There’s no amendment form. Fill out a new W-9 with the correct information and send it to the same requester, who replaces the old one. Catching the error before the requester files 1099s avoids the name/TIN mismatch entirely. If an incorrect 1099 has already gone out, the requester may receive an IRS notice directing them to solicit a corrected TIN from you.⁵

What a Bad W-9 Actually Costs

The immediate consequence is backup withholding. When the payer can’t verify your TIN or the IRS flags a mismatch, the payer withholds 24% of every payment to you and sends it to the IRS.¹⁰ You can claim the withheld amount as a credit on your tax return, so the money isn’t lost, but it’s gone from your cash flow until you file.

The payer also faces penalties for filing information returns with incorrect TINs. Under federal regulations, each return filed with a wrong TIN carries a penalty, and an incorrect TIN is never treated as an inconsequential error.¹¹ That penalty falls on the payer, which is why payers often refuse a W-9 that looks questionable and start backup withholding at the first sign of a problem. The penalty can be waived for reasonable cause.¹² For you, the practical lesson is the same either way: fill out Line 1 and Part I to match, and the rest of the form stops being dangerous.

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
12
Office of the Law Revision Counsel. 26 USC 6724