Last updated: 5 June 2024

Key points

  • Each data breach response needs to be tailored to the circumstances of the incident.
  • In general, a data breach response should follow four key steps: contain, assess, notify and review.


Data breaches can be caused or exacerbated by a variety of factors, involve different types of personal information, and give rise to a range of actual or potential harms to individuals and entities.

As such, there is no single way of responding to a data breach. Each breach will need to be dealt with on a case-by-case basis, with an understanding of the risks posed by a breach and the actions that would be most effective in reducing or removing these risks.

This diagram summarises the data breach response process. Generally, the actions taken following a data breach should include four key steps:

Step 1: Contain the data breach to prevent any further compromise of personal information.

Step 2: Assess the data breach by gathering the facts and evaluating the risks, including potential harm to affected individuals and, where possible, taking action to remediate any risk of harm.

Step 3: Notify individuals and the Commissioner if required. If the breach is an ‘eligible data breach’ under the NDB scheme, it may be mandatory for the entity to notify.

Step 4: Review the incident and consider what actions can be taken to prevent future breaches.

At any time, entities should take remedial action, where possible, to limit the impact of the breach on affected individuals. If remedial action is successful in preventing a likely risk of serious harm to individuals, the NDB scheme notification obligations may not apply.

In general, entities should:

  • take each data breach or suspected data breach seriously and move immediately to contain, assess and remediate the incident. Breaches that may initially seem immaterial may be significant when their full implications are assessed
  • undertake steps 1 (Contain), 2 (Assess), and 3 (Notify) either simultaneously or in quick succession. In some cases it may be appropriate to notify individuals immediately, before containment or assessment of the breach occurs
  • determine how to respond on a case-by-case basis. Depending on the breach, not all steps may be necessary, or some steps may be combined. In some cases, an entity may take additional steps that are specific to the nature of the breach.

Step 1: Contain

Once an entity has discovered or suspects that a data breach has occurred, it should immediately take action to limit the breach.

For example, stop the unauthorised practice, recover the records, or shut down the system that was breached. If it is not practical to shut down the system, or if it would result in loss of evidence, then revoke or change computer access privileges or address weaknesses in physical or electronic security.

Addressing the following questions may help you identify strategies to contain a data breach:

  • How did the data breach occur?
  • Is the personal information still being shared, disclosed, or lost without authorisation?
  • Who has access to the personal information?
  • What can be done to secure the information, or stop the unauthorised access or disclosure, and reduce the risk of harm to affected individuals?

At this point, an entity may suspect an eligible data breach under the NDB scheme has occurred, which would trigger assessment obligations. Or, the entity may believe the data breach is an eligible data breach, which requires them to  notify  individuals as soon as practicable.

During this preliminary stage, be careful not to destroy evidence that may be valuable in identifying the cause of the breach, or that would enable the entity to address all risks posed to affected individuals or the entity.

Step 2: Assess

An assessment of the data breach can help an entity understand the risks posed by a data breach and how these risks can be addressed. It should be conducted as expeditiously as possible.

Gather and evaluate as much information about the data breach as possible. By creating a complete picture of the data breach, an entity can ensure they understand the risk of harm to affected individuals, and identify and take all appropriate steps to limit the impact of a data breach.

This assessment should also assist entities in deciding whether affected individuals must be notified.

In your assessment of a data breach, consider:

  • the type or types of personal information involved in the data breach
  • the circumstances of the data breach, including its cause and extent
  • the nature of the harm to affected individuals, and if this harm can be removed through remedial action.

All entities should consider whether remedial action can be taken to reduce any potential harm to individuals. This might also take place during Step 1: Contain, such as by recovering lost information before it is accessed.

Entities subject to the NDB scheme are required to conduct an assessment of ‘suspected’ eligible data breaches and take reasonable steps to complete this assessment within 30 days (see Assessing a Suspected Data Breach). Criteria for assessing a data breach, including the risk of harm and remedial action, is explored in Identifying Eligible Data Breaches .

Step 3: Notify

Notification can be an important mitigation strategy that has the potential to benefit both the entity and the individuals affected by a data breach. The challenge is to determine when notification is appropriate. Sometimes, notifying individuals can cause undue stress or harm. For example, notifying individuals about a data breach that poses very little or no risk of harm can cause unnecessary anxiety. It can also de-sensitise individuals so that they don’t take a notification seriously, even when there is a real risk of serious harm. Each incident needs to be considered on a case-by-case basis to determine whether breach notification is required.


  • the obligations of the entity under the NDB scheme. Entities are required to notify individuals and the Commissioner about data breaches that are likely to result in serious harm. Part 4 of this guide provides further detail about the NDB scheme’s requirements
  • other circumstances in which individuals should be notified. For example, your entity may not have obligations under the NDB scheme, but have processes in place to notify affected individuals in certain circumstances
  • how notification should occur, including:
    • what information is provided in the notification
    • how the notification will be provided to individuals
    • who is responsible for notifying individuals and creating the notification.
  • who else other than affected individuals (and the Commissioner if the notification obligations of the NDB scheme apply) should be notified
  • where a law enforcement agency is investigating the breach, it may be appropriate to consult the investigating agency before making details of the breach public
  • whether the incident triggers reporting obligations to other entities.

Effective data breach response is about reducing or removing harm to affected individuals, while protecting the interests of your organisation or agency. Notification has the practical benefit of providing individuals with the opportunity to take steps to protect their personal information following a data breach, such as by changing account passwords or being alert to possible scams resulting from the breach. It is important that staff are capable of engaging with individuals who have been affected by a data breach with sensitivity and compassion, in order not to exacerbate or cause further harm. Notification can also help build trust in an entity, by demonstrating that privacy protection is taken seriously.

Step 4: Review

Once steps 1 to 3 have been completed, an entity should review and learn from the data breach incident to improve its personal information handling practices.

This might involve:

  • a security review including a root cause analysis of the data breach
  • a prevention plan to prevent similar incidents in future
  • audits to ensure the prevention plan is implemented
  • a review of policies and procedures and changes to reflect the lessons learned from the review
  • changes to employee selection and training practices
  • a review of service delivery partners that were involved in the breach.

In reviewing information management and data breach response, an entity can refer to the OAIC’s Guide to Securing Personal Information.[12]

When reviewing a data breach incident, it is important to use the lessons learned to strengthen the entity’s personal information security and handling practices, and to reduce the chance of reoccurrence. A data breach should be considered alongside any similar breaches that have occurred in the past, which could indicate a systemic issue with policies or procedures.

If any updates are made following a review, staff should be trained in any changes to relevant policies and procedures to ensure a quick response to a data breach.

[12] See Guide to Securing Personal Information, OAIC website <>.