Top business leader Ziggy Switkowski AO has been installed to look under the hood at embattled consultancy PwC after it became mired in a tax scandal.

The former Telstra boss will lead the review after a former PwC partner was caught sharing confidential federal government tax policy information to other partners and staff.

Peter-John Collins was found sharing the Treasury intel on measures to improve tax laws, including rules to stop multinationals avoiding tax by shifting profits from Australia to tax and secrecy havens.

The former partner has since been banned from the profession but the fallout from the scandal continues, with the firm prepared to sack more staff if the investigation calls for it.

"We will not hesitate to take the recommended actions, including, where appropriate, exiting further people and partners from the firm," the firm said in a statement. 

On Monday, PwC announced Tom Seymour - who had already stepped down from his position as chief executive officer - would retire in September to "enable an orderly transition".

The company has also brought in a global leader with the firm as a chief risk and ethics leader.

PwC Australia acting head Kristin Stubbins said Dr Switkowski would be empowered to perform a rigorous and robust review of the firm's governance, accountability and culture.

"We are committed to learning from our mistakes and ensuring that we embrace the high standards of governance, culture and accountability that our people, clients and external stakeholders rightly expect."

The federal government has also been under pressure from the Greens, independents and others to ban government contracts and do more to punish the firm.