What is Bank Tax?

Legal Definition
A bank tax ("bank levy") is a tax on banks. One of the earliest modern uses of the term "bank tax" occurred in the context of the financial crisis of 2007–08.

On 16 April 2010, the International Monetary Fund (IMF) proposed the idea of a "financial stability contribution" (FSC), which many media have referred to as a "bank tax." It was proposed as one of three possible options to deal with the crisis. These options were presented in response to an earlier request of the G-20 leaders, at the September 2009 Pittsburgh summit, for an investigative report on all possible options to deal with the crisis.

Both before and after that IMF report, there was considerable debate amongst national leaders as to whether such a "bank tax" should be global or semi-global, or whether it should be applied only in certain nations.
-- Wikipedia