Australia's merger regime swaps automatic voids for court supervision

A targeted rewrite effective 16 September 2026

Australia's mandatory merger control regime, in force only since 1 January 2026, has had its first significant amendments. Parliament passed Schedule 4 of the Treasury Laws Amendment (Strengthening Accountability for Tax Adviser Misconduct and Other Measures) Bill 2026 on 10 September 2026 [2][3]. The Bill received Royal Assent on 15 September 2026 as Act No. 86 of 2026, and Schedule 4 commences on the day after Royal Assent, so the ACCC now records 16 September 2026 as the effective date [1][2][3].

Schedule 4 delivers what the Government called targeted refinements rather than a new architecture. Three changes matter most for transaction planning: the treatment of acquisitions that should have been notified but were not; the control and associate tests that determine whether notification is required at all; and the lifespan of an ACCC clearance when a deal is delayed [1][3]. Each responds to a practical difficulty that surfaced during the regime's first months of operation [5][6].

Non-notified acquisitions move from void to voidable

Under the original design, an acquisition that met the notification thresholds but was not notified to the ACCC was automatically void from the outset, regardless of whether the omission was deliberate or accidental and regardless of the effect on lenders, customers, suppliers and employees [5][6]. From 16 September 2026 that automatic voiding is replaced by a court-supervised model: the ACCC must apply to the Federal Court for a declaration that the acquisition is void, and the Court retains discretion to decline where voiding would be undesirable, for example where it would cause significant harm to innocent third parties or where the vendor has been wound up [1][3][5].

The ACCC has a six-year window to bring a voiding application, and the Court can make consequential remedial orders, including divestiture [5]. Significantly, the Court cannot revisit the competition merits: it cannot consider whether the non-notified acquisition would substantially lessen competition. That preserves the ACCC as first-instance decision-maker and stops parties using a court process to bypass notification [5]. The amendments are not retrospective and apply to acquisitions put into effect on or after commencement [6].

• Automatic voiding is retained where a notified deal is completed before final consideration, while still under review, or after a block [5][6].
• Penalties for failing to notify are unchanged: the greater of $100 million, 30% of Australian turnover, or three times the benefit obtained [5].
• The ACCC gains a power to seek injunctions that freeze integration activity while it investigates or pursues a voiding application [5][6].

Control and associates: a narrower notification net

The second change addresses minority investments. The regime requires notification where an acquisition confers control of a target above monetary thresholds, with control previously assessed by reference to section 50AA of the Corporations Act 2001 and, notably, joint control through associates defined broadly under Chapter 6 [5]. That breadth meant parties to the same shareholders' agreement could be treated as jointly controlling a target even where neither could practically influence its competitive conduct [5][6].

Control is now judged by whether the acquirer, alone or with associates, has the capacity in a real and practical sense to determine the outcome of decisions about the target's financial and operating policies [5]. The associate definition is narrowed to the same corporate group, or an agreement or concerted action aimed at controlling or influencing those policies [5]. Express carve-outs exclude minority shareholder protection rights, dividend policy arrangements, arm's-length financing, standard governance agreements, rights to dispose of securities and professional advisory relationships [5][6]. The bright-line voting-power thresholds are unchanged and operate independently of the control analysis [5].

Stale clearances get an extension mechanism

Under the regime an ACCC-approved transaction becomes stale if it is not put into effect within 12 months of the ACCC's determination; previously, delayed parties had to re-notify and restart the process [6]. The amendments let parties request an extension before an approval lapses, and the ACCC may grant extensions of up to six months at a time, and multiple extensions where appropriate [6]. In deciding, the ACCC weighs the reason for the delay, whether market conditions have materially changed, and whether a fresh notification would be more appropriate [6].

What the early operating data shows

The refinements arrive as the regime's own data becomes visible. In its first operational update, published 9 April 2026, the ACCC reported that more than 90% of notified acquisitions or waivers were approved or granted within 20 business days, ahead of its pre-commencement expectation of about 80% [7]. The waiver pathway proved far more popular than forecast, with 152 waiver applications received to 30 April 2026, an average of about 38 a month against a predicted 8.3, while Phase 1 applications ran at roughly 30% of the predicted volume [7].

Waivers were also cheaper and faster: a filing fee of about AU$8,300 against AU$56,800 for Phase 1, and an average of 12 business days to grant a waiver against 19 business days for a Phase 1 decision [7]. Only four applications progressed to Phase 2, none were blocked, and no conditions were imposed on approved notified acquisitions in the period covered [7].

Oakhampton inference: notification becomes a deal-design decision

Oakhampton's inference is that the amendments shift merger control from a binary compliance risk into a design variable. The voidable model reduces the tail risk that a missed notification silently unwinds a completed deal and destabilises financing and supply arrangements, but it does not reduce the obligation to notify, and a six-year limitation period keeps that exposure live for years after completion [5][6]. For boards and sponsors, the practical work is mapping each acquisition against the narrowed control and associate tests before signing, not after [5].

The narrower associate definition is also a structuring opportunity. Co-investors in venture, private equity and infrastructure consortiums can hold customary minority protections and governance rights with less risk of being drawn into a joint-control analysis, which should reduce avoidable notifications and re-cut the risk allocation in agreements drafted under the earlier framework [5][6].

Remaining uncertainty

The reach of the voidable model is untested: how readily the Federal Court will exercise its discretion to refuse a voiding order, and how the ACCC will use its injunction and six-year enforcement powers, will emerge only through cases [3][5]. The control and associate amendments rest on a real and practical control test whose boundaries are inherently fact-specific, and the Minister can prescribe further excluded arrangements over time [5][6]. The extension mechanism depends on ACCC discretion rather than a fixed entitlement [6]. The commencement date is also worth pinning carefully: legislation commences the day after Royal Assent, and the ACCC records 16 September 2026, while some commentary refers to 15 September [1][2].