In April 2008, Visa implemented an international service assessment (ISA) fee of 0.40% (forty basis points).
The ISA fee applies to all transaction involving a U.S.-based business and a foreign card issuer.
The ISA is separate from interchange, and from Visa’s standard assessment fee, which is currently 0.11%.
For example, an ISA fee of 0.40% will be added to a transaction where a customer pays using her Visa-branded credit card that is issued by a bank based outside of the United States.
Since the ISA is separate from interchange and other assessments, Visa’s total assessment on this type of transaction is the sum of the ISA fee (0.40%), the standard assessment (0.11%), and the International Acquirer Fee 0.45%).
Visa also charges an interchange service assessment to card-issuing banks, but this aspect of the fee is refunded to acquiring (processing) banks.
Here is Visa’s brief online statement about the ISA fee.