Australia’s merger control regime: What the latest amendments mean for businesses

Australia’s mandatory merger control regime commenced on 1 January 2026 and is now an important consideration for businesses contemplating acquisitions, mergers and consolidations.

On 16 September 2026, Schedule 4 of the Treasury Laws Amendment (Strengthening Accountability for Tax Adviser Misconduct and Other Measures) Act 2026 (Cth) (Amending Act) came into effect, introducing important legal and operational changes that may affect transaction planning, timing and risk management.

The amendments also provide Macpherson Kelley with an opportunity to reflect on how the regime has operated during its first nine months and what we have observed in practice.

How Australia’s mandatory merger control regime works

The reforms inserted Part IVA into the Competition and Consumer Act 2010 (Cth), replacing the existing voluntary merger clearance process with a mandatory merger notification regime. Parties to acquisitions meeting prescribed thresholds must notify the ACCC before completion. Captured acquisitions are suspensory, meaning they cannot complete until the ACCC grants clearance. Notification thresholds are based on the turnover of the parties and transaction size, rather than the earlier “rule of thumb” guidance based on market share.

While notification thresholds have been imposed, the underlying competition test for approval has not changed. The transaction must not be likely to substantially lessen competition in a market (SLC Test).

For more information about the regime, including notification thresholds, timing and fees, see our earlier insight.

What happens if a notifiable acquisition proceeds without approval?

One of the most significant changes in the Amending Act is the shift for non-notified acquisitions that meet the notification thresholds from being automatically void to being voidable.

As originally enacted, an acquisition completed without required notification was automatically void—regardless of the circumstances or the result of the SLC Test. This had the potential to create harsh consequences where a failure to notify resulted from a genuine mistake or a good-faith difference of opinion about threshold calculations. Unwinding completed transactions would often be commercially and practically unfeasible.

Under the Amending Act, the ACCC may instead apply to the Federal Court for orders declaring a non-notified acquisition void, requiring divestiture or granting other remedies. Importantly, the Court must not have regard to the competitive effects of the transaction.

Significant penalties still apply for the failure to notify. The change preserves a critical incentive to comply while ensuring any further consequences remain proportionate and subject to judicial oversight.

What other September 2026 changes affect transactions?

• Control and associates: New definitions clarify which interests held by “Associates” are relevant when assessing control. They carve out ordinary commercial arrangements such as minority shareholder protections, financing agreements and professional advisory relationships.
• Extension of approval periods: Parties have 12 months after approval to complete a notified acquisition. The ACCC may now agree to extend this period by up to six months where there are reasonable grounds for delay. Extensions must be published on the Acquisitions Register.

What do the first nine months of ACCC data tell us?

While these amendments refine the legislative framework, it is also worth considering how the regime has operated in practice since commencement.

The ACCC publishes statistics on the regime’s operation (most recently updated August 2026), covering notification volumes, determination outcomes, assessment timeframes and industry breakdowns. Recent clearance decisions include Peter Warren / Wakeling Automotive (approved with conditions, 4 September 2026) and Kimberly-Clark / Kenvue (approved subject to divestiture of Carefree and Stayfree brands, 2 September 2026).

In the statistics published for the year ended 30 June 2026, the tables below show assessment time frames, determination outcomes and the leading industry sectors for notifications and waiver requests.

What should businesses do now?

The amendments don’t change our advice: if you are contemplating an acquisition or sale, engage with our team early. Many transactions will not meet the notification thresholds. However, where a transaction does, or may, meet those thresholds, the notification process should be factored into transaction timelines and pre-conditions.

Also, the SLC Test applies to all transactions. Where the notification thresholds are met, notification is mandatory.  If there is a possibility that the SLC test may be breached, then seeking clearance or a waiver is strongly recommended.

Having said that, Australia’s competitive markets also mean that the notification waiver process can be a practical and effective option for acquisitions that might raise limited competition concerns.

For further information, please contact Paul Kirton.

The information contained in this article is general in nature and cannot be relied on as legal advice nor does it create an engagement. Please contact one of our lawyers listed above for advice about your specific situation.