How to Fill Out a W-9 for Your Business: TIN, Signature, and Updates

Filling out a W-9 for your business means putting four pieces of information on a one-page IRS form in the exact way the IRS expects to see them: your legal name, your federal tax classification, your address, and your taxpayer identification number. You sign it, hand it to whoever asked, and keep a copy. The form takes about five minutes once you know which name and which number to use for your entity type. Getting either one wrong is what causes the trouble: name-TIN mismatches trigger IRS notices to your payer, and a missing or invalid W-9 forces the payer to withhold 24 percent of your payments and send it to the IRS instead.¹

Get the Current Form First

Download Form W-9 directly from the IRS at irs.gov/forms-pubs/about-form-w-9.² The current revision is dated March 2024 in the upper left corner. An older version can be rejected, so check that date before you write anything. You do not file the W-9 with the IRS. You give it to the business or person that requested it.

If your business is a corporation, partnership, or multi-member LLC and you don’t yet have an Employer Identification Number, apply online at the IRS website. The application is free, you get the EIN immediately, and you need a Social Security number or ITIN for the responsible party plus a U.S. principal place of business.³ There is no reason to hold up a W-9 while waiting on an EIN.

Line 1: The Name on Your Tax Return

Line 1 is the name exactly as it appears on your income tax return.⁴ For a sole proprietor that is your personal name, not your business name. For a corporation or partnership it is the entity’s legal name. This is the most important line on the form, because the IRS matches whatever you write here against the taxpayer identification number in Part I. Minor spelling differences cause mismatches.

Line 2: Business or DBA Name

Line 2 is for a business name, trade name, or “doing business as” name that differs from Line 1. Sole proprietors who operate under a DBA put it here. If your entity doesn’t use a separate trade name, leave Line 2 blank.

Line 3a: Federal Tax Classification

Check exactly one box that describes how your business is classified for federal tax purposes:⁴

Individual/sole proprietor if you run the business yourself without forming a separate legal entity.
C corporation for a corporation taxed under the default corporate rules.
S corporation for a corporation that elected pass-through taxation by filing Form 2553.⁵
Partnership for two or more owners sharing profits and losses.
Trust/estate for a fiduciary entity.
LLC, in which case you also enter a letter in the space provided: C for C corporation, S for S corporation, or P for partnership. A single-member LLC that hasn’t elected corporate treatment does not use this box (see below).

Classification affects whether the payer issues you a 1099 at all. Corporations are generally exempt from 1099 reporting on most payment types.⁶

Line 4: Exemption Codes

Most small businesses and sole proprietors leave Line 4 blank. It exists for entities exempt from backup withholding or from FATCA reporting. Corporations, for instance, generally enter code “5” in the first field.⁴ Individuals and sole proprietors are not exempt. If you’re unsure whether you qualify, leave the line blank; entering a code you don’t qualify for causes problems, while leaving it blank does not.

Lines 5 and 6: Address

Enter the address where you want to receive tax documents such as Form 1099-NEC.⁷ Match the address on your tax return when possible. Line 5 is the street address (with any apartment or suite number). Line 6 is the city, state, and ZIP code. A P.O. box is fine if that’s where you get mail. Consistency across your tax filings matters because mismatched addresses delay correspondence.

Part I: Your Taxpayer Identification Number

Part I is where your nine-digit Social Security number or Employer Identification Number goes. Which number depends on your structure:⁴

Sole proprietors may use either SSN or EIN. The IRS encourages the SSN.
Corporations and partnerships use the entity’s EIN.
LLCs taxed as corporations or partnerships use the LLC’s EIN.
Single-member LLCs treated as disregarded entities use the owner’s SSN or EIN, not the LLC’s EIN.

The number must match the name on Line 1. When a name and TIN don’t match, the IRS sends the payer a CP2100 or CP2100A notice instructing them to begin backup withholding on your payments.⁸

Part II: Signature and Certification

You sign and date under penalties of perjury. Your signature certifies three things: the TIN is correct, you are not subject to backup withholding (unless the IRS has notified you that you are), and you are a U.S. person.⁴ If the IRS has previously notified you that you are subject to backup withholding due to underreporting of interest or dividends, cross out item 2 of the certification before signing.⁹

Electronic signatures are accepted. Signing through a client portal, DocuSign, or a similar platform is valid so long as the requester’s system verifies the signer’s identity, captures the perjury statement, and can produce a hard copy on request.¹⁰

The Single-Member LLC Trap

Single-member LLCs that haven’t elected corporate taxation are disregarded entities, and this is where W-9s go wrong most often. The IRS does not see your LLC as a separate income taxpayer, so:¹¹

Line 1 gets your personal name.
Line 2 gets your LLC’s name.
Line 3a is checked “Individual/sole proprietor,” not “LLC.”
Part I gets your SSN or your own EIN as the owner, not any separate EIN your LLC obtained for employment tax purposes.

Reversing the names or using the LLC’s employment-tax EIN nearly guarantees a name-TIN mismatch and the backup withholding that follows.

Who Signs for an Entity

A sole proprietor or single-member LLC owner signs personally. For a corporation, an authorized officer signs. For a partnership or multi-member LLC, a general partner or authorized member signs.⁴ The signer must have legal authority to certify the entity’s tax information, not simply access to the paperwork.

Sending It and How Long It Lasts

A W-9 carries your SSN or EIN, so treat it like any other sensitive financial document. Encrypted email, a secure client portal, or a password-protected PDF are the safer options. An unencrypted email attachment is not. Physical mail works but adds transit time.

The completed form has no set expiration. It stays valid until your information changes or the payer has reason to believe the details are no longer accurate.¹⁰ Some companies ask for a fresh W-9 every year as internal policy; the IRS doesn’t require that.

When to Send an Updated W-9

Send a new W-9 to every active payer when any of the following changes:

Your legal name, after a merger, acquisition, or rebranding.
Your tax classification, such as an LLC electing S corporation status by filing Form 2553.⁵
Your address, so 1099s reach the right place.
Your TIN, if you switch from SSN to a new EIN.
Your backup withholding status, if the IRS notifies you that you are no longer subject to it.

Don’t wait for year-end. Updating payers early avoids corrected 1099s and payments withheld at 24 percent because the records on file went stale.

What Ignoring or Falsifying a W-9 Costs

Without a valid W-9 on file, the payer is required by law to withhold 24 percent of your payments and remit it to the IRS.¹ You can recover that money when you file your return, but it sits with the government until then.

Beyond withholding, the IRS can impose a $50 penalty each time you fail to provide your TIN when properly requested, up to $100,000 in a calendar year.¹² Providing false information to avoid backup withholding raises the civil penalty to $500 per false statement.¹³ Willfully signing a W-9 you know contains false information is a federal felony, punishable by fine and up to three years in prison.¹⁴ Prosecutions are rare, but the statute covers any intentional lie on the form.

If You Aren’t a U.S. Person, Use a W-8 Instead

The W-9 is only for U.S. persons: citizens, resident aliens, businesses formed under U.S. law, domestic trusts, and domestic estates.⁴ A foreign individual submits Form W-8BEN; a foreign entity submits Form W-8BEN-E. If a payer sends you a W-9 and you aren’t a U.S. person, returning a W-9 would be incorrect and would create tax reporting problems on both sides.

1
Internal Revenue Service. Publication 15 (2026)
2
Internal Revenue Service. About Form W-9, Request for Taxpayer Identification Number and Certification
3
Internal Revenue Service. Get an Employer Identification Number
4
Internal Revenue Service. Form W-9 (Rev. March 2024)
5
Internal Revenue Service. About Form 2553, Election by a Small Business Corporation
6
Internal Revenue Service. Am I Required to File a Form 1099 or Other Information Return
7
Internal Revenue Service. Form 1099-NEC (Rev. April 2025)
8
Internal Revenue Service. IRS Sends CP2100 and 2100A Notices
9
Office of the Law Revision Counsel. 26 U.S.C. 3406 – Backup Withholding
10
Internal Revenue Service. Instructions for the Requester of Form W-9 (03/2024)
11
Internal Revenue Service. Single Member Limited Liability Companies
12
eCFR. 26 CFR 301.6723-1
13
Office of the Law Revision Counsel. 26 U.S.C. 6682
14
Office of the Law Revision Counsel. 26 U.S.C. 7206