Guide
W-9 vs W-8: Which Form Does Your Vendor Need?
By Keelstar Team · Updated June 1, 2026
The short answer
U.S. persons and U.S. businesses complete Form W-9. Foreign persons and foreign entities complete a Form W-8 (typically W-8BEN for individuals or W-8BEN-E for entities). If status is unclear, ask before the first payment — the form determines 1099 reporting, FATCA reporting, and whether withholding applies.
The short answer
Domestic vendor → W-9. Foreign vendor → W-8. The W-8 family has several variants depending on whether the payee is an individual or entity and whether they claim treaty benefits.
W-9: who files it
Form W-9 is for U.S. persons — including U.S. citizens, resident aliens, and entities formed under U.S. law. The vendor certifies their TIN and that they are not subject to backup withholding (unless they are). You use it to prepare information returns such as 1099-NEC.
W-8: who files it
Form W-8BEN is commonly used by foreign individuals. Form W-8BEN-E is used by foreign entities. These forms establish foreign status and may document reduced withholding under an income tax treaty. They are not substitutes for a W-9.
Why getting it wrong matters
Using a W-9 for a foreign payee can lead to incorrect 1099 reporting and failure to withhold when required. Using a W-8 for a domestic payee delays onboarding and creates filing errors. The cost shows up at year-end or in an audit — not on day one.
What to do when unsure
Ask the vendor to confirm tax residency and entity type before payment. If they operate internationally, request the appropriate W-8 with a completed treaty claim when applicable. Document the decision in the vendor file.
Operational tip
Route vendors through a single onboarding packet that branches by tax status — W-9 path vs W-8 path — so AP never has to guess which attachment to send.
Related guides
Put this into a monitored workflow
W-9 Collector handles this continuously — with reminders and an audit trail.