An investigation caught a former tax partner at PricewaterhouseCoopers (PwC) sharing confidential Treasury information about multinational tax evasion reforms to other partners and staff.

The former head of international tax has been deregistered by the Tax Practitioners Board and banned from the profession for two years for leaking the sensitive information.

Chalmers said he was “ropeable” about the revelations.

“There is no consultation without trust,” he told reporters in Canberra.

“This is a shocking breach of trust, an appalling breach of trust.”

He said the incident put ongoing consultation work at risk.

“That puts the quality of economic decision-making in policymaking at risk as well.”

The treasurer is consulting with the assistant treasurer Stephen Jones to ensure consultancy firms honour confidentiality obligations when working with government departments.

The chair of the Board of Taxation and the head of the Australian Taxation Office have also been contacted for their recommendations on the matter.

“Obviously, when something like this is alleged, we make sure that we’re being diligent and making sure that it’s not happening elsewhere, and that it doesn’t happen again,” Chalmers said.

PwC has been ordered to improve processes and training to ensure conflicts of interest are managed better.

The Albanese government promised to crack down on multinational tax avoidance during the federal election.

Labor pledged to support a “two pillar” approach to crack down on multinational tax avoidance, which includes a 15 per cent floor rate for corporate tax globally to help eliminate tax havens.