What Is a Request for Taxpayer ID and Certification?

A Request for Taxpayer Identification Number and Certification, better known as IRS Form W-9, is the form a business gives you when it needs your taxpayer identification number before paying you. You provide your legal name, your Social Security number or Employer Identification Number, your federal tax classification, and a signature under penalty of perjury. The payor keeps the form and uses the information to file year-end returns with the IRS. You never send the W-9 to the IRS yourself.

Fill it out promptly and correctly. A delay, a wrong name, or a mismatched TIN can trigger 24% backup withholding on every payment that payor makes to you.

When Someone Will Ask You for One

Federal law requires anyone making certain reportable payments to collect the recipient’s TIN before paying.1Internal Revenue Service. A Guide to Information Returns The common triggers:

In every case the payor asks and the payee (you) fills it out. The payor stores the form in their records.

What You Need Before Starting

Have three things in front of you.

Your TIN. Individuals use their Social Security number. Businesses and other entities use an Employer Identification Number. A sole proprietor without employees can use either.4Internal Revenue Service. Form W-9 (Rev. March 2024)

Your legal name as it appears on your federal tax return. The name and TIN combination must match what the IRS has on file. A mismatch is one of the most common reasons payors get error notices, and it’s usually what puts backup withholding in motion later.

Your federal tax classification. Line 3a asks you to check one box: individual/sole proprietor, C corporation, S corporation, partnership, trust or estate, or limited liability company. An LLC also enters a letter identifying whether it’s taxed as a C corporation (C), S corporation (S), or partnership (P).4Internal Revenue Service. Form W-9 (Rev. March 2024) If you’re not sure, look at your most recent federal return or the IRS confirmation letter you received when you applied for your EIN.

The Single-Member LLC Trap

This one causes more W-9 errors than any other. If you own a single-member LLC that hasn’t elected corporate tax treatment, the IRS treats it as a “disregarded entity” — for federal tax purposes your LLC essentially doesn’t exist. On the W-9 you put your own name on Line 1 and the LLC’s name on Line 2. You check the box for individual/sole proprietor, not the LLC box. The TIN you provide is your SSN or your personal EIN as the owner, not any separate EIN the LLC obtained.5Internal Revenue Service. Instructions for the Requester of Form W-9 (Rev. March 2024)

Filling Out the Form

The current version is Form W-9 (Rev. March 2024), available at irs.gov/FormW9. Download a fresh copy rather than reusing an old one a client emailed you, since outdated revisions can cause processing delays.

Line 1 (Name). Your legal name exactly as it appears on your federal tax return. For a business entity, the entity name from its return.4Internal Revenue Service. Form W-9 (Rev. March 2024)

Line 2 (Business name). Any trade name or “doing business as” name that differs from Line 1. Leave blank if it doesn’t apply.

Line 3a (Federal tax classification). Check one box only.

Lines 5 and 6 (Address). The mailing address where you want to receive tax documents like 1099 forms. Full street address, city, state, and ZIP.

Part I (TIN). Your SSN or EIN. If you’ve applied for a TIN but haven’t received it yet, write “Applied For,” but be aware that backup withholding applies to any payments made before you furnish the number.

What You’re Signing in Part II

Your signature carries real legal weight. You are certifying under penalty of perjury that four things are true: the TIN you provided is correct, you are not subject to backup withholding (or you are, and you’ve crossed out that statement), you are a U.S. person, and any FATCA code you entered is correct.4Internal Revenue Service. Form W-9 (Rev. March 2024) If the IRS has already notified you that you are subject to backup withholding because of underreported interest or dividends, cross out item 2 of the certification before signing.

Exempt Payee Codes and FATCA (Lines 3b and 4)

Most individuals leave these blank. They exist for entities exempt from backup withholding or from Foreign Account Tax Compliance Act reporting.

Entities exempt from backup withholding include corporations, tax-exempt organizations under Section 501(a), the U.S. government and its agencies, state and local governments, foreign governments, registered securities dealers, real estate investment trusts, and certain financial institutions. Each exempt type has a numbered code (1 through 13) that goes on Line 3b.6Internal Revenue Service. Instructions for the Requester of Form W-9 (03/2024) Corporations are exempt from backup withholding on most payment types, but not on payments settled through payment card or third-party network transactions.

The FATCA exemption codes on Line 4 (A through M) apply almost exclusively to accounts held at foreign financial institutions. An individual filling out a W-9 for a domestic payor should leave Line 4 blank.4Internal Revenue Service. Form W-9 (Rev. March 2024)

If You’re Not a U.S. Person

Form W-9 is only for U.S. persons: U.S. citizens (including citizens living abroad), U.S. resident aliens, and entities organized under U.S. law. A nonresident alien individual provides Form W-8BEN instead. Foreign entities use Form W-8BEN-E.7Internal Revenue Service. Instructions for Form W-8BEN The dividing line for non-citizens is usually the substantial presence test.8Internal Revenue Service. Substantial Presence Test Signing a W-9 as a U.S. person when you aren’t one is a false certification.

Sending It Safely

A completed W-9 contains everything an identity thief needs: your name, address, and SSN or EIN. Treat it accordingly. Use a secure upload portal if the requester offers one. If you must send a physical copy, use certified mail or a trackable service. Emailing an unencrypted PDF is common practice and the riskiest method.

Never provide a W-9 to someone you weren’t expecting to hear from. The IRS does not initiate contact by email, text, or social media.9Internal Revenue Service. Ways to Tell if the IRS Is Reaching Out or if It’s a Scammer A legitimate W-9 request comes from a business you actually deal with: a new client, your bank, a property manager. Unsolicited requests, especially anything claiming to be from the IRS, should be reported through the IRS phishing page before you respond.

When to Send an Updated W-9

Provide a new form whenever your name, TIN, or business structure changes. If you incorporated your sole proprietorship, changed your legal name, or received a new EIN, send an updated W-9 to every payor holding your old information. There’s no formal IRS deadline, but the practical one is before the payor files its next 1099. Outdated information there produces mismatch notices for both of you.

What Happens If You Don’t Provide One

Refusing or failing to return a W-9 triggers backup withholding under Internal Revenue Code Section 3406. The payor is legally required to deduct 24% from every reportable payment and send that money to the IRS instead of to you.10Office of the Law Revision Counsel. 26 USC 3406 – Backup Withholding That rate was confirmed for 2026 after Congress permanently extended the individual tax rates.11Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide

Backup withholding also starts when the IRS notifies the payor that the TIN you gave is incorrect, or when you’ve been flagged for underreporting interest and dividends. It continues on every payment until you fix the problem by furnishing a valid W-9 with the correct TIN.

The money isn’t gone permanently. The payor reports the withholding on the 1099 they send you at year-end, and you claim it as federal income tax already paid when you file your return.12Internal Revenue Service. Topic No. 307, Backup Withholding But recovering it means waiting through filing season and refund processing.

Civil Penalty for Failing to Furnish a TIN

Beyond backup withholding, the IRS can assess a $50 civil penalty each time you fail to provide your TIN when required, up to $100,000 per calendar year.13Office of the Law Revision Counsel. 26 USC 6723 – Failure to Comply With Other Information Reporting Requirements The penalty can be waived if you show reasonable cause and the failure wasn’t due to willful neglect.14Office of the Law Revision Counsel. 26 USC 6724 – Waiver; Definitions and Special Rules

Criminal Penalty for False Information

Willfully providing a false TIN or lying about your backup withholding status is a felony under 26 USC 7206. The maximum penalty is a fine of up to $250,000 for individuals ($500,000 for corporations) and up to three years in prison.15Office of the Law Revision Counsel. 26 USC 7206 – Fraud and False Statements Prosecution requires the government to prove willfulness. An honest mistake will not put you in federal court, but deliberately using a fake or borrowed SSN to avoid taxes is exactly the conduct the statute targets.