Finance Index
What is Form 1042-S and when do we file it for foreign vendors?
Reference guide to Form 1042-S foreign vendor withholding, including vendor records, onboarding requirements, compliance checks, fraud controls, and payment readiness.
Form 1042-S reports US-source income paid to foreign persons and any tax withheld on it - the foreign-payee counterpart to the 1099. If you pay foreign vendors for services performed in the US, royalties, rents, or other US-source FDAP income, you generally must withhold (30% by default, less under a valid treaty claim) and file a 1042-S per payee plus an annual Form 1042.
At a Glance
| Aspect | Short Answer | Why It Matters |
|---|---|---|
| Form 1042-S | Form 1042-S reports US-source income paid to foreign persons and any tax withheld on it - the foreign-payee counterpart to the 1099. | Reduces payment errors, timing issues, and reconciliation cleanup. |
| Payment impact | For services, source follows where the work is physically performed - not where the vendor lives, where you are, or where the money goes. | Reduces payment errors, timing issues, and reconciliation cleanup. |
| Apply a treaty rate instead | You may reduce withholding only on the strength of a valid W-8 claiming the treaty: the payee's treaty country, the specific article and claimed rate, a foreign TIN (or US TIN where required), and for entities the limitation-on-benefits certification. | Keeps vendor records and payment decisions reliable. |
| Payments to foreign vendors | US-source FDAP: services performed in the US, royalties for US use (including many software license structures), US rents, interest, and similar. | Reduces payment errors, timing issues, and reconciliation cleanup. |
| Deposit and report 1042 withholding | Withhold at payment, deposit electronically on the required schedule (frequency scales with amounts withheld), file the annual Form 1042 return plus a 1042-S for each recipient by March 15, and furnish recipient copies. | Reduces payment errors, timing issues, and reconciliation cleanup. |
What makes a payment US-source - the rule AP actually needs?
For services, source follows where the work is physically performed - not where the vendor lives, where you are, or where the money goes. A developer in another country working from there: foreign-source, no withholding, no 1042-S. The same developer working on-site in your US office: US-source, withholding applies. Royalties source to where the rights are used; this is why "where was the work done?" belongs on your foreign-vendor intake form.
How do I apply a treaty rate instead of 30%?
You may reduce withholding only on the strength of a valid W-8 claiming the treaty: the payee's treaty country, the specific article and claimed rate, a foreign TIN (or US TIN where required), and for entities the limitation-on-benefits certification. Incomplete claim, expired form, or facts you know contradict it - withhold 30%. The withholding agent bears the liability for under-withholding, which is why the paperwork standard is strict.
Which payments to foreign vendors are subject to chapter 3 withholding?
US-source FDAP: services performed in the US, royalties for US use (including many software license structures), US rents, interest, and similar. Services performed entirely abroad and purchases of goods are outside the regime.
How do I deposit and report 1042 withholding?
Withhold at payment, deposit electronically on the required schedule (frequency scales with amounts withheld), file the annual Form 1042 return plus a 1042-S for each recipient by March 15, and furnish recipient copies. Form 1042 is due even for years you withheld nothing but made reportable payments.
We paid a foreign contractor for US-based work all year with no withholding and no W-8 - what's our exposure?
As withholding agent you're on the hook for the un-withheld tax plus interest and penalties - the IRS doesn't need to chase the foreign payee when it can assess you. Fix forward immediately (W-8, correct withholding), then size the look-back with a tax advisor; voluntary correction beats discovery.
Do we file a 1042-S for foreign goods purchases, SaaS subscriptions, or services performed entirely abroad?
Goods: no. Services performed entirely outside the US: no - foreign-source. SaaS: it depends on whether the arrangement is characterized as a service or a royalty/license and where rights are used - the genuinely hard case, worth a tax opinion if the dollars are material.
1099 vs 1042-S - a simple decision rule?
US person (W-9 on file) -> 1099 rules. Foreign person (W-8 on file) -> 1042-S rules, but only for US-source income. No valid form -> presumption rules and default withholding. The form on file decides the regime; that's why collection at onboarding is a control, not paperwork.
How should AP track which vendors are 1042-S reportable?
On the vendor record: foreign status flag, W-8 type and expiration date, income type, treaty country/article/rate, and the applied withholding rate. If that data lives in a spreadsheet next to the vendor master instead of on it, the payment run can't enforce it.
Stampli perspective
Stampli's customizable onboarding forms let teams route international vendors through a different intake - capturing the documentation and banking details foreign payees require - with documents stored on the vendor record and visible alongside complete payment history. That gives AP the per-vendor evidence trail that chapter 3 compliance is built on.