Mandatory Merger Control in Australia: Preparing for a new era

12 minute read 02.09.2025 Geoff Carter, Miranda Noble, Haydn Flack, Katrina Groshinski

Described as "the biggest changes to Australian merger control law in 50 years", a formal mandatory and suspensory merger control regime will come into effect from 1 January 2026.

What you need to know (and when)

Following a lengthy campaign by the Australian Competition and Consumer Commission (ACCC) – in late 2024 the Australian Parliament passed laws to introduce a mandatory and suspensory merger control regime. This will replace the current voluntary system and will have implications not only for domestic transactions, but also cross-border and multinational deals with an Australian connection.

The government has promoted the changes as introducing a system that is faster, simpler, more targeted and more transparent. Whether that occurs remains to be seen. At least in the interim, businesses and advisers should be preparing for a more complex and inflexible regime that will require more work, earlier.

It is important to understand that:

While mandatory notification requirements will take effect from 1 January 2026, the incoming regime commenced on a voluntary basis from 1 July 2025.
The incoming regime will apply to acquisitions 'put into effect' (i.e. completed) from 1 January 2026. This means that deals signed in 2025 that may not complete until 2026 require a merger control engagement strategy that accounts for the new regime and transitional arrangements.
In the second half of 2025, strategic decisions around filings and filing pathways will become increasingly critical.

ACCC staff will be working to avoid disruptions as Australia transitions to the new regime. Turbulence is, however, unavoidable.

Careful planning will be essential to navigate these changes successfully.

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Key features of Australia's new Merger Control Regime

Mandatory Notifications and Thresholds
Notification Waiver and Early Determination
ACCC Engagement
Forms, Filings and Fees
Creeping Acquisitions

Mandatory Notifications and Thresholds

Mandatory Notification, thresholds and consequences

Australia is shifting from a voluntary to a mandatory and suspensory regime.

Where a relevant acquisition satisfies the thresholds (see table below), notification is compulsory. This applies even if there is no overlap, and no perceived or potential antitrust issues. Failing to notify where notification is required will mean the deal is void and will expose the parties to a risk of significant financial penalties.

Notification Waiver and Early Determination

Notification ‘Waiver’ and ‘Early Determination' processes

The ACCC has indicated that it expects to clear around 80% of notified acquisitions within 15-20 business days. Achieving this will require significant reliance on waiver and 'fast track' processes that are designed to filter uncontroversial acquisitions. Engagement will still be required for uncontroversial acquisitions that meet the thresholds, and all notified acquisitions will be listed on a register (subject to narrow exceptions).

ACCC Engagement

ACCC Engagement will be key

The ACCC will be the primary decision maker, rather than an enforcer requiring court orders to block a deal as is currently the case. The process is intended to be more structured and public, with less flexibility for parties (and the ACCC) and more limited confidentiality options. While the government has promoted greater timing certainty, the ACCC will be able to pause and re-start the clock, subject to limits.

The ACCC has emphasised the importance of pre-engagement prior to a filing. This will be an essential part of the process, including to manage timing and information requirements. A collaborative working relationship with ACCC staff will be important, including a detailed understanding of ACCC processes and staff approach as the regime is imbedded. This will be a significant cultural change for the regulator.

Forms, Filings and Fees

The new regime will involve prescribed forms and fees, and the filing of more material upfront including transaction documents and (in some cases) Board materials regarding the transaction and the market. The detail of the filing and the documents required upfront will depend on the complexity of the issues.

The filing fees associated with the new process are material compared to the current informal regime where no fees apply. The fees will depend on the complexity of the filing, ranging from A$8,300 for a waiver application, A$56,800 for a standard Phase 1 review, and then substantial fees for complex reviews (A$475,000 – A$1,595,000 for Phase 2, and a further A$401,000 if public benefits are raised).

Creeping Acquisitions

Creeping acquisitions and entrenching market power

The new regime is designed to target creeping acquisitions and transactions that entrench market positions. Key features of the new regime include:

Thresholds that include a 3-Year ‘Look Back’: Successive acquisitions involving targets that predominately deal in the same goods or services over the prior 3 years will be relevant to the notification thresholds.
Consideration of Past Transactions: The regime has been structured to enable the ACCC to take into account earlier acquisitions when assessing the competitive effects of a proposed acquisition.
Entrenching Market Power: While the substantive test that the ACCC applies is largely unchanged, acquisitions that create, strengthen, or entrench substantial positions of market power will also be prohibited.

Why do the reforms matter for businesses and advisers

The reforms will inevitably add time and complexity to merger clearance processes in Australia. Advisers must take account of the reforms in the context of multi-jurisdictional analysis and filing strategies – this includes for due diligence, the form of conditions precedent, and approach to timetabling global filings.

Deals signed in 2025 may still need to navigate the new merger control regime depending on timing of completion, making early strategic planning even more important.

With detailed knowledge of Australia's new merger control regime, our team is ready to support businesses and advisers in managing the changes ahead and securing timely approvals."

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