What's different here
- 1099-K or 1099-NEC? If the platform is a payment settlement entity, settling card or third-party-network transactions between buyers and sellers, it files 1099-K at the $20,000 / 200-transaction threshold. If the platform is itself the payer of compensation for services (it hires the drivers, it commissions the work), it files 1099-NEC at the ordinary threshold. Many platforms do both for different flows, and getting the split wrong is the most common structural error.
- TIN verification has to be real time. A payee who fails onboarding can be asked to fix it on the spot; a payee who fails in December has been paid all year. The IRS's own program (25 pairs per request, bulk in 24 hours) doesn't fit signup; an API does.
- Backup withholding at volume means engineering, not a spreadsheet: a withholding flag on the payee record, applied automatically to each payout, deposited on schedule, reported on Form 945 and in box 4. The liability for not withholding scales with payout volume.
- Fraud and sanctions. Synthetic identities, mule accounts and sanctioned parties show up in payee onboarding before they show up anywhere else. A TIN that matches a name is one signal; OFAC screening and address validation are the others.
- Foreign payees are a large share on global platforms and need a W-8, not a W-9, with the services-sourcing rule deciding whether anything is reportable at all. See the foreign vendors guide.
Design points for the onboarding flow
- Collect the W-9 electronically with the certification text displayed and an e-signature, and store the IP, timestamp and form version; that is what makes it a valid electronic W-9.
- Ask whether the TIN is an SSN or EIN before asking for the name, and validate the format client-side before calling the IRS.
- Match on signup; on a code 2 or 3, show the payee the likely fix (usually line 1) and let them resubmit.
- Set the withholding flag automatically on a missing TIN and on the 30-business-day CP2100 deadline; clear it on a matched resubmission.
- Log every solicitation, match and B-Notice per payee; at 50,000 payees a 972CG is a data question, not a letter-writing one.