I am the sole shareholder of a Delaware C-Corp. Revenues are generated off-shore in China and Germany. Our services are also offshore - we just use a US bank account. These are no US operations aside from our mailing address in California

What forms do we have to fill out (W9, etc). to pay a vendor in Malaysia who worked for us on a project in China? The vendor will be paid from our US bank account.

You, as a payer, DO NOT fill out a W8BEN for the vendor in Malaysia, and neither does the Malaysian vendor UNLESS the vendor was physically presented in US or the vendor’s services are provided inside the US.However, the Malaysian vendor can fill it out for you as there is no penalty in filling out the form W8BEN.But actually as said, the vendor does not need to fill out the form W8BEN since the income the vendor receives is NOT from US sources. So you , as a payer, DO NOT need to withhold 30% of US tax on the payments made to the foreign vendor for the vendor overseas. The vendor does not need to file his return with the IRS either. So you do not even need to fill out a W9 to pay the foreign vendor since he does not need to file his return with the IRS on the payments from you .This means that the foreign vendor does not even need an ITIN from the IRS. Also, You do not send a 1099 to the foreign vendor so you do not need to submit 1099/1096 to the IRS either.