Australia’s merger control framework is entering a new era after Parliament passed the Treasury Laws Amendment (Mergers and Acquisitions Reform) Act 2024, which will officially shift the Australian Competition and Consumer Commission (ACCC) into a first-instance decision-making role on certain acquisitions.

Under the current regime, firms may proceed with transactions that risk a substantial lessening of competition (SLC) without needing notification to the ACCC.

As of 1 July 2025 a transitional phase has begun.

During this period parties may voluntarily notify acquisitions under the incoming mandatory scheme or continue to use the existing informal clearance route until 31 December 2025. The mandatory, suspensory notification regime will take full effect on 1 January 2026 for acquisitions that meet the prescribed thresholds.

Under the new rules, transactions that meet defined monetary and control thresholds must be submitted for approval—and may not legally proceed without clearance.

The ACCC’s published guidance confirms that post-notification, the acquisition cannot be completed until the ACCC provides its decision.

Failing to notify a notifiable acquisition or proceeding before clearance will render the deal void and expose parties to significant penalties.

Key changes include the ability for the ACCC to aggregate prior acquisitions undertaken by the same acquirer over the previous three years (‘creeping acquisitions’) when assessing clearance.

The ACCC can also scrutinise non-horizontal transactions and previously excluded asset categories such as real estate or land rights, which will now attract notification risk depending on the circumstances.

The regulations released to date establish revenue and value thresholds.

For example, a transaction will trigger notification if the combined Australian revenue of acquirer and target is at least A$200 million and the target’s Australian revenue is at least A$50 million, or the global value is at least A$250 million.

For very large acquirers (Australian revenue above A$500 million) other lower thresholds apply.

These rules reflect the final form of the Competition and Consumer (Notification of Acquisitions) Determination 2025.

Several transitional guardrails have been introduced: trust existing informal approvals granted between 1 July and 31 December 2025 provided completion occurs within 12 months; authorisation applications under the current regime are no longer possible from 1 July 2025; and waiver applications (where firms seek relief from notification) are now available.

Practitioners warn that the shift demands earlier planning, deeper diligence, and careful structuring of acquisitions with an Australian nexus—especially cross-border deals.

Early voluntary filings have already been filed (for example, leases of warehouse and aerotropolis land) and cleared within 15 business days.

These filings signal both the ACCC’s intention to lean into the new regime and market readiness for the transition.

The reform is widely regarded as the most significant overhaul of Australia’s merger control laws in decades, positioning the country closer to the regimes of other advanced jurisdictions and signalling stronger competition scrutiny at the gate.

As the January 2026 start-date draws near, businesses will need to adjust their M&A strategies to reflect the greater transparency, stricter thresholds and timelier review envisioned under the new regime.