When the Standard Formula Does Not Fit Your Family
The Australian child support formula is designed to work for the broad majority of families. It takes each parent's income, the cost of the children and the level of care, and produces an assessment. But families are not averages, and the formula cannot account for every circumstance. Some parents face costs the formula never imagined; some have incomes that do not reflect their true capacity; some have financial resources that an income figure alone simply misses.
For these situations, the child support scheme provides the change of assessment process. It allows the standard assessment to be varied where special circumstances exist and the result would otherwise be unjust or inequitable. This page explains how that process works, the recognised reasons, the evidence required, and the review options if you disagree with the outcome. To understand objections and the broader dispute pathways, also read the Child Support Disputes page.
What a Change of Assessment Is
A change of assessment application asks Services Australia to depart from the standard formula in your particular case. Either parent can apply. The agency considers whether one of the recognised reasons applies, whether special circumstances exist, and whether changing the assessment would be just, equitable and otherwise proper. It is an administrative process — not a court case — and it is one of the most powerful tools available to a parent whose assessment does not reflect reality.
Importantly, a change of assessment is not a way to express general unhappiness with the figure. It is a structured process built around specific reasons, and an application succeeds when it squarely meets one of those reasons and is backed by the right evidence.
The 10 Reasons for a Change of Assessment
The legislation sets out ten recognised reasons on which a change of assessment can be based. In broad terms, they cover:
- The high costs of enabling a parent to spend time with, or communicate with, a child
- Special needs of the child that increase the cost of caring for them
- Extra costs of caring for, educating or training the child in the manner both parents intended
- The child support assessment being affected by the child's own income, earning capacity, property or financial resources
- Money, property or other payments already provided for the child's benefit
- The high costs of child care for the child (typically where the child is under a certain age)
- A parent's necessary expenses significantly affecting their capacity to support the child
- The assessment not properly reflecting a parent's income, property, financial resources or earning capacity
- A parent's legal duty to maintain another person or other children
- A parent's responsibility to support a resident child
Each reason has its own requirements and its own evidentiary threshold. The right reason — or sometimes more than one — depends entirely on the facts of your case. Identifying the correct reason and framing the application around it is where a child support advocate's experience is invaluable.
The Special Circumstances That Commonly Arise
In practice, certain situations come up again and again. Understanding how they map onto the recognised reasons helps you see whether a change of assessment may be open to you.
High Costs of Spending Time With a Child
Where parents live far apart, the cost of travel for a child to spend time with a parent — flights, fuel, accommodation — can be substantial. Where those costs exceed a relevant threshold, they can form the basis of a change of assessment.
Special Needs of a Child
A child with a disability, chronic illness, or other special needs can be far more expensive to raise than the formula assumes. Medical costs, therapy, equipment and care can all be relevant special circumstances.
Income, Property and Earning Capacity
This is one of the most contested areas. The formula relies on taxable income, but taxable income can be a poor measure of real financial capacity. A parent who has reduced their hours, structured income through a business or trust, or is deliberately under-earning may have an earning capacity well above the figure on their tax return. Conversely, a parent's income may be overstated by a one-off event. The change of assessment process can address both, asking whether the assessment properly reflects a parent's true income, property, financial resources or earning capacity.
Self-Employed and Variable Income
Self-employed parents and those with fluctuating or seasonal income are some of the hardest cases for the standard formula to handle. Deductions, retained business profits, and timing differences can make taxable income look very different from cash actually available. These cases often turn on careful financial analysis — exactly the kind of detail Simon Bacon specialises in.
Property and Financial Resources
A parent might have significant assets or financial resources that generate little or no taxable income — investment properties, business holdings, or family-controlled entities. Where these resources realistically support a higher level of child support, they can be relevant to a change of assessment.
The Evidence You Will Need
Change of assessment applications live or die on evidence. The agency does not take assertions at face value; it looks for documentation that proves the special circumstance and quantifies its effect. Depending on the reason, relevant evidence may include:
- Tax returns, financial statements and business accounts
- Bank statements and records of cash flow
- Receipts and invoices for travel, medical, education or care costs
- Medical reports or documentation of a child's special needs
- Records of property holdings, trusts and company structures
- Evidence of earning capacity, such as qualifications, work history and the local job market
- Correspondence and records of the parenting and care arrangements
Assembling this material in a way that directly addresses the recognised reason — rather than dumping a pile of paper on the agency — is what makes an application persuasive. A focused, well-evidenced application is far stronger than a sprawling, unfocused one.
Timelines and How the Process Runs
Once a change of assessment application is lodged, the other parent is given the opportunity to respond, and the agency considers both sides before making a decision. The process is more involved than a simple recalculation because it requires the agency to weigh special circumstances and exercise discretion. Decisions take time, and the quality of the application heavily influences both how long it takes and the outcome.
A change of assessment decision can apply to current and, in some cases, past or future periods, depending on the circumstances. Because the rules around the relevant period are technical, getting advice before you lodge can make a real difference to the result.
Review Options if You Disagree
If you are dissatisfied with a change of assessment decision, you generally have further options. You can object to the decision through the agency's objection process, and if you remain dissatisfied, the matter can be escalated to the Administrative Review Tribunal (ART) — the body that replaced the Administrative Appeals Tribunal (AAT) in October 2024 for child support reviews. As with all child support disputes, strict time limits apply at each stage, so prompt action is essential. The objection and review pathways are explained in more detail on the Child Support Disputes page.
How Simon Bacon Helps
Change of assessment is one of the most technically demanding areas of the child support system, and it is precisely where deep expertise pays off. Simon Bacon helps parents:
- Determine whether a change of assessment is genuinely open to them, and on which reason
- Build the financial and factual case that meets the agency's criteria
- Marshal and present the right evidence in a focused, persuasive way
- Anticipate and respond to the other parent's position
- Navigate timelines, periods and the review pathway if needed
If your child support assessment does not reflect your family's real circumstances — whether the costs you carry, the income involved, or the resources behind it — a change of assessment may be the answer. To find out, talk it through with someone who knows the process inside out.
Read more about Simon on the About page, browse common questions in the FAQ, or call Simon Bacon on (02) 9137 4130 to discuss whether a change of assessment could improve your situation.