
Collecting W-9s and Avoiding Backup Withholding: A Vendor-Onboarding Playbook
The IRS requires 24% backup withholding when a vendor's TIN is missing or incorrect. This playbook covers collecting W-9s before the first payment, validating them, using the free IRS TIN Matching Program, responding to CP2100 B-notices within 15 business days, and why the new $2,000 1099-NEC threshold for 2026 doesn't change when you need a W-9.










