After spending a fortune on a campaign designed to improve its tarnished image and ward off a royal commission, the banking sector must have done a collective face palm as news swirled that Commonwealth Bank was at the centre of shocking allegations of "serious and systemic non compliance" under the Anti Money Laundering and Counter Terrorism Financing Act.

If it sounds ominous it is. Banks trade on trust and robust systems. When this breaks down, heads must roll.

In the words of Austrac: "It is essential to the integrity of the financial system that a major bank such as CommBank has compliant and appropriate risk based systems and controls in place to deter money laundering and terrorism finance."

CBA says it is cooperating with Austrac but it is yet to officially respond to the allegations. Until then, they remain allegations. But the response is something the board and chief executive Ian Narev will need to carefully think about.