Financial institutions serve a “gatekeeper” role when it comes to preventing and addressing money laundering conducted by (or through) their clients. The Dutch regulator is requiring Dutch banks to significantly improve their “know-your-customer” rules and test their clients much more thoroughly for aggressive tax planning. This article discusses the new guidance issued in the form of a consultation paper that was published on 7 February 2019 on what constitutes “good practice” when it comes to financial institutions screening their clients for aggressive tax planning structures.