Australia’s New Merger Regime Has Started, and It’s Turning M&A Into an Execution Discipline

For most of modern Australian corporate history, mergers have operated under a familiar dynamic. Companies could choose whether to engage with the regulator early, manage the timing strategically, and, in many cases, treat approval as a risk to be managed rather than a gating step that controlled the whole sequence.

That world has changed. From 1 January 2026, Australia moved to a mandatory merger notification regime for acquisitions that meet certain thresholds, and those acquisitions must not proceed until they have been assessed and cleared. In other words, the system has become both mandatory and suspensory for notifiable deals. 

This is not just a legal adjustment. It changes how strategy leaders, corporate development teams, and executives need to think about deal-making. Because once a transaction becomes “notifiable”, it also becomes a process with a clock, dependencies, and public visibility. M&A becomes less like a discrete corporate action and more like a complex execution program.

The change is simple, but the implications are not.

At the centre of the reform is a straightforward shift: certain acquisitions must be notified to the ACCC and cannot be put into effect until cleared, unless a waiver applies.  That “cannot proceed until cleared” feature is the quiet disruptor. It means deal timing can no longer be treated as something you negotiate mainly between buyer, seller, and financiers. Regulatory sequencing becomes a structural constraint. It influences how you design the entire move, from diligence and communications through to integration planning and even internal resourcing.

Treasury’s own material makes clear that while the core merger system commenced on 1 January 2026, some aspects around thresholds were deferred, including changes to certain control and asset thresholds, which Treasury notes will commence on 1 April 2026. 

That detail matters because it signals what businesses are already feeling: the regime is live, but it is also still bedding down in its specifics. Which means the practical burden for strategy teams isn’t just “learn the rule.” It’s “operate under a new rule while parts of it are still evolving.”

What changes inside organisations first is not the deal thesis , it’s the operating model around the deal

Most executive teams think about M&A in terms of the strategic logic: market entry, capability acquisition, scale economics, portfolio reshaping. That logic still matters, of course. But the first-order change introduced by a mandatory, suspensory regime is operational.

In a voluntary system, teams could often progress a deal deep into the pipeline and decide later how aggressively to engage the regulator. Under a mandatory system, the approach has to be designed much earlier.

You need earlier internal alignment on what you are buying, why it matters, and what the competition risks could plausibly be, because those questions now affect not just approval probability, but timing, messaging, resource allocation, and stakeholder management. When clearance becomes a gating step, anything that extends the process becomes a direct cost.

This is why the change turns M&A into an execution discipline. The work moves forward. The decision points move upstream. The sequencing becomes less forgiving.

Deal risk becomes timeline risk, and timeline risk becomes organisational risk

There is a simple way to understand the practical consequence of a suspensory regime: it increases the cost of uncertainty.

If an organisation cannot complete a notifiable acquisition until cleared, it has to manage the downstream effects of delay. That includes internal distraction, leadership bandwidth, opportunity cost, and the coordination burden placed on teams who are asked to plan integration without certainty about timing.

In the past, deal teams could often treat these risks as secondary. Under a suspensory regime, they become central. The longer the clearance process, the longer the organisation must remain in a state of partial commitment, not fully integrated, but not fully able to move on.

For strategy leaders, this is where M&A begins to resemble transformation work. You need governance, clear ownership, structured decision-making, and a realistic plan for managing uncertainty. Otherwise, the process itself becomes a drag on the rest of the strategic portfolio.

The strategic consequence is earlier discipline and fewer casual deals

One predictable outcome of mandatory notification is that it raises the internal bar for “going live” with a deal. Not because deals become unattractive, but because the organisational cost of a weakly-prepared deal increases.

When a transaction triggers a formal regulatory pathway, the organisation has to be ready for scrutiny and sequencing. That tends to reduce casual opportunism. It rewards clarity. It favours deals where the strategic logic is sharp enough to justify the time, the internal coordination, and the exposure.

This is not necessarily a reduction in ambition. It is a shift toward commitment discipline. It becomes harder to carry deals that are “maybe strategic” but not strongly defended. Strategy leaders often say they want less noise in the portfolio and more focus on what matters. A mandatory, suspensory merger system has a way of forcing that.

What strategy leaders should take from this

The key insight is not that Australia has changed its merger rules. That fact is now settled: mandatory notification for certain acquisitions began on 1 January 2026, with Treasury indicating the core regime commenced as planned and some threshold settings deferred to 1 April 2026. 

The key insight is what that does to organisational behaviour. It pushes M&A closer to the discipline of execution. It forces earlier alignment. It increases the cost of drift. It rewards teams who can sequence decisions cleanly and communicate them clearly.

And it makes one thing very visible: in a suspensory regime, strategy is not just what you decide to do. It is what you can move through a system of approvals, timelines, and constraints, without losing momentum or organisational trust along the way.