The reworked merger rules will put corporate marriages primarily in the hands of the Australian Competition and Consumer Commission and ditch the voluntary disclosure scheme in favour of a mandatory regime.

Treasurer Jim Chalmers will deliver the Bannerman competition lecture in Sydney and say Australia is one of only three OECD countries without compulsory merger notification.

Under the voluntary regime, the ACCC only assesses about a quarter of all mergers, restricting its visibility and raising the chance of an anti-competitive combination slipping through the cracks.

“Australia’s approach to mergers is no longer fit for purpose,” Dr Chalmers will say.

“The changes I announce today are the biggest reforms to merger settings in almost 50 years.”

Competition policy has become a focal point for the government as it vies to boost flagging productivity and spur innovation.

It has launched several probes and investigations spanning different sections of the economy, including the supermarket sector that’s under fire for its pricing practices.

Most Australian sectors are dominated by a few big players and Treasury research suggests a lack of competition increases the cost of doing business and can lead to higher prices and lower wage growth.

Dr Chalmers hopes the reworked merger rules will be part of a “fifth wave” of competition policy reform that, much like earlier efforts, will unleash strong economic growth and improved productivity.

“Competition policy is a growth strategy,” he will say.

“Because competition moves capital to new growth opportunities in the economy.”

Tougher merger rules have long been on the ACCC’s wishlist and while businesses viewed some of its earlier proposals “excessive”, the treasurer believes a middle ground has been found.

Under the changes, merger laws will be updated to better handle serial acquisitions, which is where a firm incrementally acquires a number of smaller companies and the overall process simplified.

“It will be more targeted, because mergers that create, strengthen or entrench substantial market power will be identified and stopped while those consistent with our national economic interest will be fast tracked,” he will say in his speech.

“The new reforms will make our merger approval regime faster, stronger, simpler, more targeted and more transparent.”

ACCC chair Gina Cass-Gottlieb welcomed the changes.

“These proposed changes are significant and will reinforce public confidence in Australia’s competition laws,” she said.

The government also wants to appoint law and economics academic and merger expert Philip Williams AM as an ACCC commissioner and to set up a public register of all mergers and acquisitions.

The laws are set to come into force at the start of 2026, provided they make it through parliament.