Most merchant acquirers, as well as the US Government, will interpret sections 312 and 326 of the US Patriot Act to require a Social Security Number to positively identify a merchant application and to check the applicant against various financial crimes and terrorist lists. This essentially prohibits non-US companies. There are some exceptions, but this is generally the rule.

Many of the card acceptance solutions that do not require this information are not actually issuing merchant accounts or are otherwise performing what is known as aggregration or is opening a merchant account on your behalf that they own. Some are also issuing merchant accounts in non-US banks. Others are in violation of US law.