If all investors are being run through the 506(c) (which is usually the case, unless there is a concurrent Reg S offering for the international investors), the verification process is the same for them, meaning they have to upload the documents which prove their category of accreditation.
If your lawyer advises that background searches are required on investors and you have turned on DealMaker’s background check functionality, international investors are checked against OFAC watchlists, and will be required to upload a piece of ID as well as provide a tax ID, in order for the background check to be completed. Tax ID is not needed for 506(c) verification, in most cases. It is only required to complete background checks.
DealMaker will intuitively guide investors through questions that apply to their situation, as such investors from outside the United States, for example, will not be asked to identify their EIN.