Finance Index
What is a W-9 and when do I need one from a vendor?
Reference guide to W-9 collection vendors, including vendor records, onboarding requirements, compliance checks, fraud controls, and payment readiness.
Form W-9 is the IRS form a US person or entity uses to certify its legal name, taxpayer identification number (TIN), and federal tax classification. AP needs it to determine 1099 reportability and to file accurate information returns. Best practice is to require a W-9 from every US vendor before first payment - collecting at onboarding, when you have leverage, beats chasing in January.
At a Glance
| Aspect | Short Answer | Why It Matters |
|---|---|---|
| A W-9 | Form W-9 is the IRS form a US person or entity uses to certify its legal name, taxpayer identification number (TIN), and federal tax classification. | Keeps vendor records and payment decisions reliable. |
| Vendor impact | Collect from everyone, decide reportability later. | Keeps vendor records and payment decisions reliable. |
| Control point | Yes - require the W-9 before vendor activation, not before year-end. | Keeps vendor records and payment decisions reliable. |
| Collect w-9s at scale | Escalate in steps: portal request with reminders, then a notice that payments will hold until receipt, then actual payment hold - payment leverage outperforms every other tactic. | Reduces payment errors, timing issues, and reconciliation cleanup. |
| Payment impact | You can, but you must generally begin backup withholding at 24% on reportable payments, remit it via Form 945, and still file the 1099 with the information you have. | Reduces payment errors, timing issues, and reconciliation cleanup. |
Which vendors need a W-9 - do corporations need one too?
Collect from everyone, decide reportability later. Yes, corporations too: the W-9's tax-classification box is your documented evidence that the vendor is a corporation and therefore generally 1099-exempt - without it you're guessing. Universal collection also future-proofs you against classification changes and exception categories (attorneys and medical payments are reportable even to corporations).
Should the policy be "no W-9, no pay"?
Yes - require the W-9 before vendor activation, not before year-end. It's the only point in the relationship where you hold all the leverage. The legal backstop: if a payee won't provide a TIN, you're generally required to backup-withhold 24% from reportable payments - so "no W-9" doesn't mean "no consequences," it means withholding, paperwork, and remittance obligations you don't want.
How do I collect w-9s at scale from hundreds of vendors who ignore email?
Escalate in steps: portal request with reminders, then a notice that payments will hold until receipt, then actual payment hold - payment leverage outperforms every other tactic. Time the campaign to active vendors first (they have invoices pending), and document each solicitation for penalty-abatement evidence.
Vendor refuses to provide a W-9 - can I still pay them?
You can, but you must generally begin backup withholding at 24% on reportable payments, remit it via Form 945, and still file the 1099 with the information you have. Practically, most teams hold payment instead - refusal usually produces a W-9 quickly.
How do I validate a W-9 is filled out correctly?
Check four things: line 1 name matches the TIN type (individual name with SSN, entity name with EIN), a tax classification box is checked, the TIN is complete and plausible, and it's signed and dated. Then TIN-match it - name/TIN mismatch is the top B-notice cause.
Does a W-9 expire - how often should we refresh?
W-9s don't expire by rule; they remain valid until the vendor's facts change. Refresh when anything changes (name, entity type, TIN) and consider a periodic refresh - every 2 - 3 years for active vendors - as hygiene against silent changes.
Vendor sent a new W-9 with a different ein - what does that mean and what do I update?
Usually a restructuring, sale, or entity change - confirm with the vendor which entity earns payments going forward and from what date. You may need two vendor records and two 1099s for the year, split at the change date. Treat an unexplained TIN change as a verification event, not a data update.
Are e-signed or portal-collected w-9s acceptable to the IRS?
Yes - the IRS permits electronic W-9 collection and e-signature, provided the electronic system reasonably ensures the signer is the person named, the signature authenticates the submission, and you can produce a hard copy on request.
How do I store w-9s securely and findably?
Attached to the vendor record in an access-controlled system - never a shared drive folder, since W-9s carry SSNs. The test: at 1099 time, can you produce every active vendor's current W-9 in one query?
W-9 for a single-member llc - SSN or ein, and whose name on line 1?
A single-member LLC is a disregarded entity by default: line 1 must show the owner's name, line 2 the LLC name, and the TIN should be the owner's SSN (the IRS prefers it, though the owner's EIN is acceptable). The LLC's own EIN on line 1 is the classic TIN-mismatch trap.
We paid a vendor all year with no W-9 - what's the cleanup before January?
Solicit immediately in writing (first solicitation is your penalty defense), hold further payments as leverage, and if nothing arrives by filing time, file the 1099 with what you have and begin backup withholding on any further payments. Document every attempt.
Stampli perspective
Stampli makes W-9 collection part of onboarding rather than a year-end scramble: vendors submit tax documents through the secure self-service portal, the documents attach to the vendor record with an audit-ready history, and customers can make a current W-9 a payability requirement - missing mandatory documents can automatically block invoices or payments.