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mergersandacquisitions.com.auThe merger notification rules, from the buyer’s side

A guide published by Dotto

Mergers and acquisitions: Australia’s merger notification rules

Since 1 January 2026, businesses must notify certain acquisitions to the ACCC and wait for its approval before they proceed. This guide, published by Dotto, follows that regime from the buyer’s side, one step at a time, from the official sources listed at the foot of each page.

General information, not legal advice. The ACCC says it cannot give legal advice about specific circumstances, only general information and guidance. The official places to check are the ACCC’s mergers and acquisitions pages and, for foreign buyers, the Treasury’s foreign investment pages.

In effect from
1 January 2026
Decision maker
The ACCC
Notifications accepted from
1 July 2025
Latest changes in effect
16 September 2026
Wooden chess pieces on a board in low sun: a pale queen and knight in focus, with dark pieces blurred behind and in front.
Pieces on the board. Photo by ha11ok on Pixabay.

What changed

From a choice to a requirement

Under the old system, notifying the ACCC of an acquisition was not compulsory. A business could choose to seek the ACCC’s views to reduce the risk of legal action, and when the ACCC thought an acquisition would substantially lessen competition and the parties did not amend or abandon it, its route was to start court action.

In 2024 Parliament passed the Treasury Laws Amendment (Mergers and Acquisitions Reform) Act 2024, which moved merger control from a judicial enforcement model to a primarily administrative one. The ACCC now decides: it determines whether a notified acquisition is approved and can be put into effect, or is not approved and must not be. The ACCC’s enforcement fact sheet calls it “the mandatory and suspensory merger control regime”.

A requirement to notify applies only to an acquisition put into effect on or after 1 January 2026, though notifications could be made from 1 July 2025. The law quoted on this site is the compilation of the Competition and Consumer Act dated 16 September 2026.

The buyer’s path

Five steps, five guides

  1. When a merger must be notified: the revenue and transaction value thresholds, the exemptions, and who lodges the notification.
  2. What the ACCC assesses: the substantial lessening of competition test, read through the ACCC’s guidelines.
  3. Merger timelines and fees: phase 1, phase 2 and the public benefit phase in business days, and what each step costs.
  4. Foreign investment review: the Treasury’s 2026 monetary thresholds and obligations for overseas buyers.
  5. Waivers, Tribunal review and penalties: the routes around a decision, and what follows an acquisition put into effect without notifying.

Key dates

The regime’s calendar so far

  1. Notifications could be made from this date, ahead of the requirement itself.
  2. The mandatory regime took effect, and the notification thresholds apply from this date unless stated otherwise.
  3. The asset thresholds and the voting power thresholds commenced.
  4. Legislative changes came into effect, covering, in the ACCC’s words, “the voiding of non-notified transactions, the control exemption, and extensions for previously approved notifications.”
  5. The first day on which the Determination’s dollar thresholds can be indexed; indexation then falls on the first day of each calendar year.

Smaller deals

When both businesses are small

The ACCC says a small business buying or merging with another small business is unlikely to meet the monetary notification thresholds, and there is no obligation to notify an acquisition that does not meet them. The thresholds only start to apply once the combined Australian revenue of the merging businesses, or the acquiring business’s revenue, is at least $200 million. Its own example is two businesses each with annual revenue under $10 million: there is no requirement to notify.

A small business being bought by a larger one is in a different position. Depending on the buyer’s size, the thresholds could be met, and the buyer may need information from the business it is buying, such as its Australian revenue, key suppliers and relevant transaction documents, to complete the notification.

The public record

Every notified deal is on the register

Once an acquisition is notified, the ACCC publishes some details on its acquisitions register and a period of consultation begins. Customers of, and suppliers to, the merging businesses may make a submission on the likely competitive effects. Written reasons for key decisions are published there too.

The ACCC also publishes data on how the regime is running, from the number of notifications to how long assessments took; its latest set covers 1 July 2025 to 30 September 2026 and was updated on 8 October 2026. The first step on the buyer’s path is the thresholds: when a merger must be notified.