Form W-9 is a US Internal Revenue Service document that US-based individuals and entities -- including independent contractors, freelancers, and sole proprietors -- complete to provide their Taxpayer Identification Number (TIN) to a client or payer. The payer uses the TIN to prepare Form 1099-NEC or 1099-MISC at year end, reporting non-employment income paid to the contractor.
The W-9 is submitted directly to the requesting client and is not filed with the IRS. It certifies the payee's name, business structure, and TIN, and confirms that the payee is not subject to backup withholding. If a contractor fails to provide a completed W-9, the payer is required to apply backup withholding at a rate of 24 per cent on all payments.
For international HR teams or global companies engaging US-based contractors, collecting a valid W-9 before the first payment is a prerequisite for compliant payroll administration. Non-US individuals and entities do not complete the W-9; they use the relevant W-8 series form instead. The Dutch equivalent of contractor income reporting is the opgaaf van uitbetaalde bedragen aan derden, submitted to the Belastingdienst by engaging parties.