The introduction of mandatory merger control in Australia introduces the biggest change in Australian deal mechanisms in decades. From 1 January 2026, Australia moved from a largely voluntary merger clearance system to a mandatory merger control regime. Certain acquisitions of shares, units or assets that meet prescribed thresholds must be notified to the Australian Competition and Consumer Commission (ACCC) and cannot be completed unless and until regulatory approval is granted.

Non‑compliance has serious consequences. Transactions implemented without formal notification, or approval, will be automatically void, exposing parties to substantial legal and commercial risk. Failure to comply with the regime may expose parties, and others sufficiently involved in the contravention, to significant penalties. The new regime marks a step‑change for Australian dealmaking, and non-compliance will kill a deal.

To avoid undue execution risk, consider the following:

• Assess the application of merger control from the get-go, so as not to be caught out by time limits or the ability to meet conditions precedent in transaction documentation
• Early due diligence should be conducted on both parties to determine if the notification thresholds will be met
• Non-compliance, even if unintentional, means a transaction is automatically void. Gun jumping is serious. Do not integrate merging businesses or unduly share information pending ACCC approval. Transaction documents should include appropriate safeguards and allow regulatory timing risk
• Exemptions and entitlement to a waiver should not be assumed
• Even if a transaction is not notifiable by reference to the thresholds, it still may be subject to the general prohibition on acquisitions that have the effect of substantially lessening of competition
• Non-compliance has the potential for significant civil penalties for bodies corporates of up to AUD50 million, or three times the benefit derived, or 30% of adjusted turnover during the breach period. For individuals, the maximum penalty is AUD2.5 million. There could also be exposure to other breaches of competition law, such as cartel conduct or misuse of market power
• There will likely be a need for deeper use of economic analysis and commentary. Do market analysis early and consider engaging economic advice at that time to deal with any substantial lessening of competition issues
• Consider what remedies may be needed in advance of merger negotiations if any likely substantially lessen competition issues could arise to mitigate prolonged or unnecessary regulatory, timing and execution risks
• Stealth or creeping acquisitions, minority equity investments, or an emphasis on boardroom or contractual rights are no panacea. Minority investments require careful assessment for falling within the notification regime. Shareholders and joint venture agreements need to be drafted with these issues in mind. Staged transactions must be analysed holistically
• Where the Australian merger control process is one in a multi-jurisdictional transaction and there are different timing or substantially lessening of competition issues with the Australian business, consider drafting ‘hold separate’ provisions in the transaction documentation and deal architecture/governance so that the transaction can complete in other jurisdictions elsewhere pending ACCC approval
• If also making a Foreign Investment Review Board (FIRB) application, ensure that the information provided to FIRB is consistent with that provided to the ACCC because they share information. FIRB will not issue its approval for a transaction until the ACCC has issued its approval where there is a dual notification to both
• Notifications will be public. Information will be publicly available on the ACCC’s acquisition register during the notification process. Notification waivers will also be published one business day after being granted or refused. Be conscious of impacts of public exposure on the deal.

This article was published as part of the Australian M&A: A review of 2025 and outlook for 2026 publication which you can read here.