Spousal maintenance and child support

How child support is calculated

Most child support is assessed administratively by Services Australia rather than by a court. The basic formula has eight steps and, once you see them laid out, it stops being mysterious.

1. Work out each parent's child support income: adjusted taxable income less a self-support amount and any relevant dependant allowance.
2. Add both to get the combined child support income.
3. Divide each parent's income by the combined income to get their income percentage.
4. Work out each parent's care percentage, based on nights of care per year.
5. Convert the care percentage to a cost percentage using the care and cost table.
6. Subtract the cost percentage from the income percentage to get the child support percentage.
7. Work out the costs of the child using the combined income and the child's age.
8. The parent with a positive child support percentage pays that percentage of the costs of the child.

Two things follow that people find counterintuitive. Care shifts the number as much as income does, because nights of care feed straight into the cost percentage. And a parent with a negative child support percentage pays nothing, because their share of the costs is already being met through care.

Payments can be collected by Services Australia or made privately by agreement. Private collection is simpler when it works and leaves you exposed when it stops.

When the formula produces the wrong number

The formula uses taxable income, which does not always describe reality. A change of assessment application asks Services Australia to depart from the formula on one of ten grounds set out in the legislation. The most commonly used are:

• High costs of spending time with or communicating with the child, such as interstate travel.
• Special needs of the child.
• Costs of caring for, educating or training the child in the way both parents intended, including private school fees.
• The child's own income, earning capacity, property or financial resources.
• Money, goods or property already provided for the child's benefit.
• High child care costs for a child under 12.
• Necessary commitments to support themselves.
• The parent's income, property, financial resources or earning capacity not being reflected in the assessment.

That last ground is the one used where a parent reduces their taxable income through a company or trust, or reduces their working hours after separation. It requires evidence rather than suspicion, and the reduction must not be justified by the parent's caring responsibilities, health or genuine need.

Parents can also make a limited child support agreement, which requires an existing assessment and a rate at or above the assessed rate, or a binding child support agreement, which requires independent legal advice for both parties and is very difficult to exit. Get advice before signing either, particularly a binding one.

Spousal and de facto partner maintenance

Section 72 of the Family Law Act imposes an obligation on a party to a marriage to maintain the other, to the extent they are reasonably able, if the other party cannot support themselves adequately. Section 90SF does the same for de facto partners.

Two questions, in order. Does the applicant have a reasonable need they cannot meet from their own income and resources. And does the other party have the capacity to pay after meeting their own reasonable expenses. If either answer is no, there is no order.

Inability to support yourself commonly arises from having care of a child under school age, age or health limiting employment, or an earning capacity that was reduced by the role you took during the relationship. Section 75(2) sets out the considerations for married couples and section 90SF(3) for de facto couples, including income, property, age, health, care of children, a suitable standard of living and, since 10 June 2025, the economic effect of family violence.

Maintenance can be urgent, interim, periodic or a lump sum. Urgent maintenance under section 77 is available where a party is in immediate need and the full case cannot be heard yet. The same time limits apply as for property: 12 months after a divorce order takes effect, or two years after a de facto relationship ends.

Adult child maintenance and other obligations

Child support normally ends when a child turns 18 or finishes secondary school in the year they turn 18. Beyond that, a court can order adult child maintenance under section 66L where it is necessary to enable the child to complete their education, or because of a mental or physical disability.

These applications are not common and they are not automatic. The court looks at the child's own resources, the parents' capacity, and whether the expenditure is genuinely necessary. A university degree, on its own, does not produce an order.

Applications can be made by a parent or by the child. Where a child has a serious disability that will continue beyond 18, this is worth planning for well before the child's eighteenth birthday, alongside any property settlement.