What the ACCC does

  • We review mergers that have the potential to raise competition concerns. This includes proposed as well as completed mergers.
  • We provide our view on the competition issues that may result from a merger.
  • We can apply to the court to prevent or unwind a merger if we consider it is likely to substantially lessen competition.

What the ACCC can't do

  • We can't oppose mergers in court that reduce competition unless the effect is substantial.
  • We can’t oppose a merger for reasons that aren’t competition related, such as community preferences or national interest considerations.

On this page

Merger control in Australia is changing

A new mandatory merger control regime for notifying and assessing acquisitions starts on 1 January 2026. The regime replaces the current informal review and merger authorisation processes.

Some changes came into effect from 1 July 2025, as we transition to the new regime.

Impact on informal review process

If you are considering using the informal review process or could have an informal review in progress this year, there are things you need to be aware of:

  • engage with us as soon as possible. This will help manage the risk that there won’t be enough time to complete a pre-assessment or informal public review before the new mandatory regime comes into effect. 
  • requests for informal reviews received after October 2025 risk not being considered in time. Even if there are limited or no competition risks, requests received between October and December 2025 are much less likely to be considered in time.

Our transition guidance provides further information and next steps about informal reviews during the key transition periods.

How to engage with the ACCC about a proposed acquisition

If you want to engage with us about an acquisition between 1 July and 31 December 2025 you can: 

  • notify using the new merger control regime on a voluntary basis
  • continue to use the current informal review process. Engage with the ACCC as early as possible to give enough time to complete the review.

About informal merger reviews

The informal merger review process lets merger parties seek the ACCC’s view on whether a proposed merger or acquisition is likely to substantially lessen competition.

There is no legislation underpinning this process. It has developed over time to provide a way for merger parties to seek our view before a merger occurs.

If we reach a view that a merger is likely to substantially lessen competition and the parties don’t agree to modify or abandon the merger, we can take court action to prevent or unwind the merger.

The informal merger review process doesn’t protect merger parties from possible legal action by the ACCC or other parties. However, a decision by the ACCC not to oppose a merger gives merger parties a level of comfort regarding our position.

Our position is based on information available at the time we make a decision. If the situation changes or more information becomes available, this position can change.

Discuss your proposed merger

We encourage merger parties to contact the ACCC as early as possible when a merger is being considered and it potentially raises competition issues.

We can discuss possible competition issues and review options. This may be done on a confidential basis.

Contact us by phone on (02) 6243 1368 or email mergers@accc.gov.au.

Starting an informal review 

Parties can ask the ACCC for a review

Merger parties can notify the ACCC and ask for an informal review by providing a submission with relevant information about their proposed merger.

The Informal merger review process guidelines lists the information required in the submission and the process we follow.

There is no fee for an informal merger review.

The ACCC can start its own review

The ACCC can also start an informal review in response to information from other sources, such as:

  • people who have made a complaint to the ACCC
  • information from Australian and overseas regulators 
  • our own monitoring activities.

We can investigate proposed mergers as well as completed mergers.

Our assessment of mergers

The merger assessment guidelines outline the analytical framework we will apply when assessing whether a merger is likely to result in a substantial lessening of competition.

Mergers considered low risk

For each merger, the ACCC makes an initial assessment based on the information available to decide whether a public review is required.

If we are satisfied that there is a low risk that the merger will substantially lessen competition, we may decide that a public review isn’t necessary. These mergers are described as being ‘pre-assessed’. They can often be considered confidentially or are sometimes assessed after conducing targeted inquiries.

Information about mergers that are pre-assessed is generally not published on the ACCC website.

A large proportion of the mergers notified to the ACCC are pre-assessed through the informal review process.

Mergers requiring a public review

We generally conduct a public informal merger review when:

  • the merger is in the public domain
  • we consider that the merger raises potential competition concerns, and
  • we need information from market participants to help us reach a view.

Register of public informal merger reviews

Public informal merger reviews that are currently under consideration or have been completed are listed on the public informal merger reviews register.

Each entry includes indicative timelines, a summary of the transaction, and the outcome of the ACCC’s review.

Mergers that have already been completed

When we investigate a merger that has already been completed, we don’t include the details on our register or post a timeline.

Completed mergers are investigated on an enforcement basis.

Possible outcomes of an informal review

The possible outcomes of an informal public merger review are:

  1. We decide not to oppose the merger.
    While this doesn’t provide protection from legal action, it provides a degree of comfort to merger parties.
     
  2. We decide not to oppose the merger, subject to a court enforceable undertaking offered by the merger parties to address the competition concerns identified by the ACCC.
    An undertaking places obligations on the merger parties to remedy the competition concerns, for example, by divesting a business or certain assets.
     
  3. We decide to oppose the merger.
    If we reach the view that a merger is likely to substantially lessen competition and the merger parties don’t agree to modify or abandon the merger, we can apply to the court for orders to prevent or unwind the merger. This may include an injunction, divestiture or penalties.

Subscribe to merger reform updates

A new mandatory merger control process starts on 1 January 2026, with a voluntary period from 1 July 2025. 

Subscribe to get the latest news and updates on the new merger process and changes during the transition period.

  • Be alerted to key dates and new information.
  • Find out when we’re seeking feedback on guidance.
Subscribe to merger reform update emails