Who signs a W-9? And who may sign for someone else

The rule: the payee, or someone authorized to sign for the payee

The payee is whoever is named on line 1 — the person or entity the payments are made to and whose number is in Part I. When you sign, you certify under penalties of perjury that the number is correct, that the payee isn't subject to backup withholding, and that it is a U.S. person. That's why the IRS ties the signature to the payee or to someone with authority to speak for it.

The form itself has only a signature line and a date line. There's no field for a title or a company name, and the IRS doesn't list which job titles count as “authorized”. Authority comes from the payee: an entity's operating agreement, bylaws or board decision; a power of attorney; a court appointment.

Individuals, sole proprietors and joint accounts

If the W-9 is for you — a freelancer, contractor or landlord paid in your own name — you sign it yourself, even if a business name appears on line 2. A sole proprietorship isn't separate from its owner.

For a joint account, the W-9 instructions say only the person whose taxpayer number is shown in Part I should sign, when a signature is required. That person's name is listed first and circled on line 1.

How to sign a W-9 as an LLC

A single-member LLC that hasn't elected corporate tax treatment is disregarded, and its W-9 names the owner on line 1. The instructions are explicit: for a disregarded entity, the person identified on line 1 must sign. If you own the LLC, you sign your own name, as its owner — not as a separate company.

An LLC with two or more members, or any LLC taxed as a corporation, is the payee itself. Someone with authority under the operating agreement signs for it — typically a managing member or manager. It helps the requester to see the capacity, for example “Jane Diaz, Managing Member” beside the signature.

Corporations and partnerships

A C or S corporation's W-9 is signed by an officer or another person the corporation has authorized — often the owner in a small company, or someone in finance in a larger one. A partnership's is signed by a general partner or a partner with authority to act for it.

An employee without signing authority — an assistant, a bookkeeper — shouldn't sign just because they filled in the form. They can prepare it; an authorized person signs.

Nonprofits, trusts and estates

A nonprofit signs through an authorized officer, and the form carries the organization's name and EIN — never an officer's or a volunteer's SSN.

A trust that files its own return signs through its trustee, with the trust's name and EIN on the form. A revocable living trust is a grantor trust, and for grantor trusts the W-9 instructions generally point to the U.S. grantor rather than the trust — unless the trust files its own Form 1041 or uses Optional Filing Method 2. In that common case the grantor's name and SSN go on the form, and the grantor signs as the payee.

An estate is signed for by its executor or personal representative. The IRS's name-and-number table is clear that the estate's own EIN is used, not the representative's number, unless the estate itself isn't named on the account.

Minors

The IRS sets no minimum age for signing a W-9. What it does specify is whose name and number go on the form: for a custodial account under the Uniform Gifts to Minors Act, give the minor's name and SSN, and circle the minor's name.

A teenager paid for their own work — modelling, tutoring, content creation — is the payee and can sign their own W-9 if the payer accepts a minor's signature. The IRS doesn't say who signs for a young child; the person who manages the child's affairs — a parent, legal guardian or the account's custodian — is the natural “person authorized to sign for the payee”, while line 1 and Part I still show the child. Ask the payer what it accepts, because age and authority rules come from state law, not from the W-9.

Can I sign a W-9 for someone else?

Only if you're authorized to sign for them: as their agent under a power of attorney, their court-appointed guardian or conservator, or as an officer, partner, trustee or executor of the payee. Being a spouse, a parent of an adult child or an office manager isn't enough on its own.

The certification is made under penalties of perjury. The W-9 warns of a $500 civil penalty for a false statement with no reasonable basis that avoids backup withholding, and criminal penalties for willfully falsifying certifications. If you're not authorized, prepare the form and let the payee sign it.

Who should not sign a W-9 at all

Anyone who isn't a U.S. person — a nonresident alien individual or a foreign company — gives the payer a Form W-8 instead. The same applies to a disregarded LLC with a foreign owner, even if the owner has a U.S. taxpayer number.

Sources

• IRS — Instructions for the Requester of Form W-9 (Rev. March 2024): Substitute Form W-9
• IRS — Form W-9 (Rev. March 2024): Part II and What Name and Number To Give the Requester
• IRS — Single member limited liability companies