Hello and thank you for using Just Answer,The US company needs the W8 to keep in their files so the IRS would be able to see that the US company paid a nonUS entity. The IRS has advised US companies that for newly used foreign vendors, a valid Form W-8 should be required before any payment is made to them to avoid application of the presumption rules or the need to obtain the documentation later.This W8 does not imply that the foreign vendor has any US tax liability but just the opposite. It allows the US company to account for the payments and the reason why no tax was withheld. Form W-8BEN should be used by the foreign vendor to certify that it has non-U.S. status. I believe the person that answered the phone call at the IRS for you was fixed on the Fixed or Determinable, Annual or Periodic (FDAP) sourcing rules. Then the sourcing rules. The W-8BEN is used to confirm that a vendor is a foreign entity and must be provided even if the vendor is not claiming a tax treaty reduction or exemption from withholding. Therefore, all foreign vendors must provide a W-8BEN, even if no EIN, ITIN, or SSN exists. Your company would be assisting the paying US company in their need to account to the IRS for payments made.
I know it seems redundant but the IRS has been charged with making sure that in an international age for business transactions, the US businesses are keeping correct records of their expenses.