Child Support Assessments and Private Agreements in Australia

What Is Child Support?

Child support is financial support paid by one parent to the other for the benefit of a child. In Australia, the child support scheme is administered by Services Australia under the Child Support (Assessment) Act 1989 (Cth).

The scheme applies to the parents of children under 18 years of age. It also extends to certain non-parent carers — such as grandparents or legal guardians — who have care of a child and are not in a domestic relationship with either parent.

Child support is separate from spousal maintenance, property settlement and parenting orders. A person may be involved in child support proceedings at the same time as family law property or parenting matters, but each operates under different legislation and different rules.

Who Must Pay Child Support?

Both parents have a legal duty to maintain their children. In most cases, the parent with the higher income and the lower percentage of care will be assessed to pay child support to the parent with the higher percentage of care. However, this is not automatic.

The assessment depends on:

• the income of both parents;
• the care arrangements — who the child lives with and how much time they spend with each parent;
• the number and ages of the children;
• whether either parent supports other children.

A parent who shares care equally may still be required to pay child support if their income is significantly higher than the other parent's income. Conversely, a parent with a very low income and minimal care may pay little or nothing.

How the Assessment Process Works

A parent or non-parent carer can apply to Services Australia for a child support assessment. The application requires details about the parents, the children, care arrangements and income.

Services Australia uses a statutory formula to calculate the amount payable. The formula is complex, but in broad terms it works as follows:

1. Combined child support income. Both parents' taxable incomes are adjusted and added together to produce a combined child support income.
2. Income percentage. Each parent's share of the combined income is expressed as a percentage.
3. Care percentage. Each parent's share of the children's care is calculated based on the number of nights the child spends with each parent.
4. Cost percentage. The care percentage is converted to a cost percentage using a legislated table.
5. Child support percentage. The cost percentage is subtracted from the income percentage. A positive result means that parent is liable to pay child support. A negative or zero result means they are not.
6. Costs of the children. The child support percentage is applied to the estimated costs of raising the children, which vary according to the combined income and the number and ages of the children.

The resulting figure is the annual child support liability. It is usually expressed as a monthly or fortnightly amount.

Income, Care Arrangements and Percentage Calculations

Income. For assessment purposes, Services Australia generally uses the parents' most recent taxable income as reported to the Australian Taxation Office. Parents can also elect to use an estimate of their current income if it has changed significantly. There are rules about when estimates can be made and how long they remain in effect.

Care percentage. Care is measured by the number of nights the child spends with each parent over a 12-month period. The percentage of care determines the cost percentage, which in turn affects who pays and how much. Even a small change in care arrangements — for example, from 35 percent to 40 percent — can produce a meaningful change in the assessment.

Parents should notify Services Australia promptly when care arrangements change. Failing to do so can result in an assessment that does not reflect the actual care being provided, with significant financial consequences for one or both parties.

For more on how care arrangements are structured, see our guide to parenting arrangements after separation.

Limited Child Support Agreements

A Limited Child Support Agreement allows parents to agree on a child support amount that departs from the formula assessment by up to 15 percent in either direction.

Key features include:

• It must be in writing and signed by both parents.
• It must be registered with Services Australia.
• Independent legal advice is not strictly required — but it is strongly recommended.
• It can be terminated after three years, or earlier if the formula assessment changes by more than 15 percent.
• Either parent can end it in certain circumstances by giving notice to Services Australia.

Limited agreements are useful when parents want a modest departure from the formula — for example, to account for slightly higher costs of living in one household or to reflect a private arrangement for extracurricular activities.

Binding Child Support Agreements

A Binding Child Support Agreement is more formal and offers greater certainty — but also less flexibility.

Key features include:

• It must be in writing and signed by both parents.
• Each parent must obtain independent legal advice from a separate Australian-qualified lawyer before signing. The lawyer must provide a certificate confirming the advice was given.
• It can set any amount of child support — above, below or equal to the formula.
• It cannot be easily terminated. It generally continues until the agreed end date, the child turns 18, or a court sets it aside.

Binding agreements are commonly used where one parent wishes to pay more than the formula requires — for example, to cover private school fees, health insurance or significant extracurricular costs — or where the parents wish to cap their liability at a fixed amount.

Because binding agreements are difficult to unwind, parents should enter them only after careful consideration of their long-term financial circumstances and with proper legal advice.

Advantages and Disadvantages of Private Agreements

Private agreements — whether limited or binding — offer several advantages over standard assessments:

• Certainty. An agreement fixes the amount and timing of payments, reducing uncertainty and conflict.
• Flexibility. Parents can tailor arrangements to their specific circumstances — school fees, health costs, lump sums, or payment of specific expenses directly to providers.
• Privacy. Agreements are between the parties and do not require ongoing Services Australia involvement if collected privately.
• Finality. A binding agreement is difficult to vary, which can protect a payer who does not want the amount reviewed repeatedly.

Disadvantages include:

• Rigidity. Binding agreements in particular may become unsuitable if incomes, care arrangements or the child's needs change significantly.
• Cost. Binding agreements require two lawyers and two advice certificates, which adds expense.
• Enforcement limitations. Private collect agreements rely on the parties' cooperation. If the payer defaults, enforcement is more difficult than with a Services Australia assessment.

Lump Sum Child Support Arrangements

In some cases, parents agree to a lump sum payment of child support rather than periodic payments. This may suit families where one parent has significant assets but limited ongoing income, or where the parties wish to finalise their financial relationship.

Lump sum arrangements can be recorded in a binding agreement. The lump sum is credited against the payer's liability over time. There are specific rules about how the credit is calculated and what happens if the lump sum is exhausted before the child turns 18.

Parents considering a lump sum arrangement should obtain legal and accounting advice to ensure the structure is fair, tax-effective and properly documented.

School Fees, Medical Expenses and Extracurricular Costs

The standard child support formula includes an allowance for the general costs of raising a child. It does not specifically account for private school fees, major medical expenses or expensive extracurricular activities.

Parents have several options for addressing these costs:

• Change of Assessment. A parent can apply to Services Australia for a departure from the formula on the ground that the costs of the child are significantly affected by high costs of caring for, educating or training the child.
• Private agreement. Parents can include specific provisions for school fees, health insurance, dental and optical costs, or extracurricular activities in a limited or binding agreement.
• Direct payment. Parents may agree that certain costs are paid directly to the school, medical provider or activity organiser rather than passing through child support.

It is important to document any private arrangement clearly. Oral agreements about school fees or medical costs are difficult to enforce if one party later disputes the arrangement.

Varying an Assessment

A child support assessment is not fixed forever. Either parent can request a new assessment when circumstances change.

Common reasons for variation include:

• a significant change in either parent's income;
• a change in care arrangements — for example, the child spending more nights with one parent;
• the birth of a new child to either parent;
• a child turning 13 (which affects the costs of children table);
• the child leaving school or starting full-time work.

Parents can update their income estimate, notify Services Australia of care changes, or apply for a formal review.

Change of Assessment Applications

A Change of Assessment is a formal review conducted by Services Australia when one of the ten statutory grounds applies. The most commonly relied on grounds include:

• the costs of the child are significantly affected by high costs of caring for, educating or training the child;
• the costs of the child are significantly affected by the child's special needs;
• the child's income, earning capacity or property is relevant;
• the parent's income, property or financial resources are relevant;
• the assessment is otherwise unfair because of the income, earning capacity or property of the child or either parent.

The review is conducted by a senior case officer who examines the evidence and may request additional documents. The decision can be appealed to the Administrative Appeals Tribunal (AAT) if either parent is dissatisfied.

Change of Assessment applications can be complex and are often opposed. Legal advice is recommended before applying or responding.

Enforcement of Unpaid Child Support

When child support is not paid, Services Australia has significant enforcement powers. These include:

• Garnishee notices. Deducting child support directly from wages, bank accounts or other income sources.
• Tax refund intercepts. Redirecting tax refunds to pay outstanding child support.
• Departure prohibition orders. Preventing a payer from leaving Australia until the debt is paid or arrangements are made.
• Credit reporting. Registering the debt with credit reporting agencies, which can affect the payer's ability to obtain loans or credit.
• Court proceedings. In serious cases, Services Australia can commence court action for the recovery of unpaid child support.

Private collect arrangements — where the parents agree to handle payments between themselves without Services Australia collection — do not have the same enforcement protections. If a payer defaults under a private collect arrangement, the payee may need to apply to Services Australia to collect the arrears or commence their own court proceedings.

Overseas Child Support Issues

Child support does not stop at the border. Australia has reciprocal arrangements with many countries for the assessment, collection and enforcement of child support.

If a parent lives overseas, Services Australia can still assess child support and, in many cases, enforce payment through the overseas jurisdiction. Similarly, if a parent moves overseas, their Australian child support liability generally continues.

The rules vary depending on the country involved and whether there is a reciprocal agreement. Parents dealing with international child support should seek advice early, as the process can involve multiple agencies and significant delays.

Common Misconceptions About Child Support

Misunderstandings about child support are common and can lead to costly mistakes. Some of the most frequent include:

• "I don't have to pay if I don't see the child." Incorrect. Child support and parenting time are separate legal issues. A parent's obligation to pay child support is not dependent on the time they spend with the child. Withholding child support because of a parenting dispute can result in enforcement action.
• "Child support is tax deductible." Incorrect. Child support payments are not tax deductible for the payer and are not assessable income for the payee.
• "The formula always produces a fair result." The formula is a starting point, not an ending point. It does not account for every family's specific circumstances. Departures and private agreements exist precisely because the formula is not always appropriate.
• "I can just pay what I think is fair." Unless there is a registered agreement or a court order, a parent cannot unilaterally decide to pay less than the assessed amount. Unilateral underpayment exposes the payer to enforcement action and arrears.

Practical Tips for Separated Parents

Separating parents can take several practical steps to manage child support effectively and avoid disputes:

• Document care arrangements. Keep a clear record of when the child is in each parent's care. Small changes can affect the assessment.
• Notify Services Australia promptly. Delay in reporting income or care changes can result in backdated assessments or arrears.
• Consider collection through Services Australia. If there is any risk of non-payment, collection through Services Australia offers stronger enforcement than a private collect arrangement.
• Get legal advice before entering a binding agreement. Binding agreements are difficult to vary. Understand the long-term implications before signing.
• Keep agreements in writing. Even informal arrangements about extra costs should be documented by email or text to avoid later disputes.
• Review arrangements regularly. Children's needs change as they grow. A review every one to two years is sensible.