What are the know-your-customer ("KYC") rules?
KYC rules are local laws that require a non-US financial institution to obtain identity documents from clients, usually relating to tax reporting and/or anti-money laundering rules. In particular, KYC rules refer to the documentation required under local law that have been approved by the IRS for purposes of establishing the identification and tax residence of a non-US person for purposes of the QI regime.
The IRS approved KYC rules can be found on the IRS web site, and have been adopted by the IRS with input from banking associations and other organizations.
A QI can rely on KYC documentation in order to establish that a client satisfies the requirements to obtain a reduced rate of US withholding.