What does “W-9” mean in bookkeeping?
W-9: A form you ask contractors to fill in before paying them, giving their tax ID so you can prepare their 1099.
Official details: About Form W-9 (IRS) (opens in a new tab)
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Related terms in US tax and payroll
Written for US bookkeeping. Last reviewed November 5, 2026. See all 100 terms.