Change of Assessment (COA)

A Change of Assessment (COA) is a way to adjust a child support assessment when the formula does not properly reflect a case situation. Either parent can apply, and Services Australia reviews the broader financial circumstances of both sides.

A COA review is a structured administrative process that requires evidence and can affect the child support assessment.

Role of COA in child support assessment

A Change of Assessment does not replace the child support formula with a different system. It changes the result of the formula assessment where special circumstances justify a different outcome.

The Registrar can make a direct decision about the assessment itself. That can mean increasing or reducing the annual rate of child support, rather than only altering the underlying inputs. In other cases, the Registrar can change one part of the formula so the assessment recalculates on a different basis.

The Registrar can set a parent’s income at a specific level if their taxable income does not reflect their true capacity to support the child. The Registrar can also directly vary the annual rate or adjust key parts of the formula, including cost percentage, child support percentage, and the costs of the child.

Change of Assessment Reasons

A COA can only be made if one or more of the following reasons is established due to special circumstances:

• Reason 1: High costs of enabling a parent to spend time with or communicate with the child.
• Reason 2: High costs associated with the child’s special needs.
• Reason 3: High costs of caring for, educating, or training the child in the way both parents expected.
• Reason 4: The assessment is unfair because of the child’s income, earning capacity, property, or financial resources.
• Reason 5: The assessment is unfair because a parent has already paid or transferred money, goods, or property for the child’s benefit.
• Reason 6: High child care costs for a child under 12.
• Reason 7: A parent’s capacity to support the child is significantly reduced due to necessary commitments to support themselves.
• Reason 8A: The assessment is unfair because of the income, property, or financial resources of one or both parents.
• Reason 8B: The assessment is unfair because of the earning capacity of one or both parents.
• Reason 9: A parent’s capacity is affected by responsibilities to support another child or person.
• Reason 10: A parent’s capacity is reduced due to responsibility for a resident child.

These reasons limit when a COA can be used. General dissatisfaction with the formula is not enough.

COA Reasons Most Commonly Accepted

The 2008–09 Child Support Scheme Facts and Figures report shows that COA decisions were dominated by financial grounds, particularly those relating to the parents’ income and earning position.

Multiple reasons can apply to a single application, so totals exceed the number of cases. Most successful COA decisions turn on income and earning capacity.

Example

One parent applies for a COA under Reason 2 because their child needs dental braces and the treatment is expensive. The applying parent provides a diagnosis, treatment plan and quote from an orthodontist.

Services Australia considers whether the cost is necessary and reasonable, and whether both parents can contribute.

A common outcome is to recognise the cost and effectively share it between the parents. For example, the Registrar may treat the braces as a specific additional cost and assign responsibility on an equal basis, with one parent required to pay extra child support to cover half the additional cost.

The decision depends on the evidence, the parents’ financial positions, and whether the adjustment is just and equitable.

What it means if you apply for a COA

If you apply for a COA, you are asking Services Australia to look beyond the formula. This requires clear evidence of special circumstances. The process involves information gathering, submissions, and a formal decision. It is more involved than a standard update but does not require going to court.

Decisions apply for a defined period. If circumstances continue to change, further applications may be needed. Each application adds time and administrative effort for both parents.

How to apply for a Change of Assessment: Special circumstances form

What it means if the other parent applies

If the other parent initiates a COA, you will be asked to respond and provide your own financial information. The Registrar considers both sides before making a decision. The outcome may increase or decrease the assessment, regardless of who applied.

A COA can affect multiple parts of the calculation. Even if only one issue is raised, the Registrar may adjust other elements if the evidence supports it. The final result is based on the overall fairness of the assessment, not just the original claim.

COA review process

If neither party appeals the decision, a change of assessment (COA) because of special circumstances follows a standard four-step administrative process.

1. Written application

Either parent (payer or payee) can apply for a COA. Applications must be made in writing using the Application to Change your Assessment – Special Circumstances form.

Sufficient information must be provided for the application to proceed. Applications may be refused at this stage where no recognised ground is established or where, on the face of the application, a change would not be just and equitable or otherwise proper under section 117 of the Child Support (Assessment) Act 1989 (CSA Act).

2. Written response

If the application is accepted, Services Australia will send a copy, and any accompanying documents, to the other party along with a response form: Response to Application to Change your Assessment – Special Circumstances. Responding to an application is not required.

3. Discussion with decision maker

Each party is generally offered an opportunity to discuss the application and response with the decision maker by phone. These discussions assist the officer in understanding the submissions but do not convert the process into an investigative inquiry.

While Services Australia may request further information, officers are not investigators and rely primarily on material provided by the parties. The process is intended to be transparent, with each party informed of, and given an opportunity to comment on, the essential considerations and information relied upon.

4. Decision based on law

Services Australia will consider and balance the evidence before it, including written and oral statements and any supporting documents, against the CSA Act and relevant policy guidance in the Child Support Guide. The decision must be legally supportable based on the material available.

A decision to change an assessment amends the existing administrative assessment. While any component variable may be adjusted, decisions most commonly involve an increase to a parent’s assessed taxable income. Changes may be backdated by up to 18 months prior to the application date.

COA Success Rates

The most complete public data on Change of Assessment outcomes comes from the 2008–09 Child Support Scheme Facts and Figures report, the final detailed statistical release from the Child Support Agency. It provides a clear picture of how often CoA applications were made and what they achieved.

In that year, 22,494 Change of Assessment applications were finalised. A majority resulted in a change to the assessment, but a substantial minority did not.

The headline figure is that 61.4% of applications resulted in the assessment being varied. That is a clear majority. At the same time, 38.6% did not produce a change, either because the application was not accepted or because the original assessment was left in place.

Acceptance and outcome are not the same. A further 16.5% of applications were accepted but did not lead to any variation. These cases still went through the full CoA process but ended with the existing assessment confirmed.

Receiving parents initiated slightly more applications than paying parents. Of all finalised cases, 50.7% were initiated by receiving parents, 42.9% by paying parents, and 6.3% by the Registrar. Among accepted applications, receiving parents accounted for 53.3% and paying parents 39.0%.

Overall, the data shows that Change of Assessment was used at significant scale and often resulted in a different outcome, but it did not guarantee a change. A large share of applications either failed or confirmed the original assessment.

How long a COA decision lasts

A Change of Assessment decision applies for a defined span of time. There is no fixed duration. The Registrar sets how long the decision will run based on the circumstances of the case.

If the situation is stable, the decision may be set to run for a longer time. If circumstances are likely to change, the decision may be limited to a shorter span so the assessment can be reviewed again.

The decision can also be structured to change over time if circumstances are expected to shift. The aim is to produce a workable assessment without requiring repeated applications.