W-9 form: collect it before you pay, not at year end

The W-9 form — Request for Taxpayer Identification Number and Certification — is how a United States business collects the legal name, tax classification and taxpayer identification number of someone it pays. The payer requests it, the payee completes it, and the payer keeps it. It is not sent to the IRS. Its whole purpose is to give the payer the details needed to file information returns correctly at year end.

The mistake is almost universal and almost always the same: paying first and collecting the form later. In January the contractor has finished the job, moved on, changed email address and has no incentive to reply — and you cannot file a correct information return without their number.

What the W-9 form gives you

• The name as shown on the payee’s tax return, and their business or disregarded entity name if different. These are frequently not the same, and using the wrong one is what triggers a mismatch notice.
• The federal tax classification — individual or sole proprietor, C corporation, S corporation, partnership, trust, or LLC with its own classification. This decides whether you have to issue an information return at all.
• The taxpayer identification number: a Social Security number or an employer identification number.
• Exemption codes where they apply, such as for certain entities exempt from backup withholding or FATCA reporting.
• Address, used for the information return.
• The payee’s signed certification that the number is correct and that they are not subject to backup withholding.

Backup withholding is the consequence

If a payee does not provide a valid taxpayer identification number, the payer is required to withhold a percentage of the payment and remit it — that is backup withholding, and it exists precisely to make missing W-9s the payer’s problem. It also applies where the IRS notifies you that a number is incorrect or that the payee has underreported. The practical implication is simple: collecting the form is not administrative diligence, it is what prevents you from having to deduct from an invoice and explain why.

Make the W-9 part of supplier onboarding, alongside the bank details, and refuse to process the first payment without it. Every organisation that has this problem solved does it that way, and every organisation that chases in January does not.

The certificate you collect at the start determines what you file at the end. A 1099 NEC reports what you paid a US contractor across the year, and every detail on it comes from the paperwork gathered before the first payment.

Editions, storage and who may see it

The form has a revision date and the IRS updates it; use the current version from the IRS site rather than a copy saved years ago, because the certifications and the classification boxes have changed over time. Store completed forms securely: they contain Social Security numbers, which makes the file a data-protection question rather than a filing one — restricted access, no emailing around the office, and a retention rule. Ettex PDF fills and flattens the form for vendors who ask you to complete one, Ettex Records holds the collected forms per vendor with access restricted and the retention date visible, and Ettex Sheets tracks which vendors are still missing one before year end rather than during it.

Being direct: this is documents and records, not tax software, and none of it is tax advice. Classifications, exemption codes, withholding rates and reporting thresholds are set by the IRS and change; your accountant and the current form instructions are the authorities.