How is Child Support Calculated in Australia?
In Australia, child support payments are calculated using a formula in Australian law. Our child support calculator uses the official 8 step formula defined by the Child Support (Assessment) Act 1989. This child support calculation aligns with Service's Australia's guidance.
Assessments are administered by Services Australia. These assessments are designed to ensure that both parents contribute to the costs of raising their children in proportion to their financial capacity and the amount of care they provide.
Basic Child Support Formula
For parents with one child support assessment, the 8 step formula is used.
- Child support income: Take each parent's adjusted taxable income and subtract the self-support amount ($31,046 in 2026) and any relevant dependant allowances.
- Combined income: Add both parents' individual child support incomes together.
- Income percentage: Divide each parent's individual child support incomes by the combined income.
- Care percentage: Divide the number of nights the child spends with each parent by the total number of nights in that period (typically measured in nights per fortnight, e.g. 14).
- Cost percentage: Determine this using each parent's care percentage and the Care and Cost Table.
- Child support percentage: Subtract each parent's cost percentage from their income percentage. (A positive result identifies the parent to pay child support, while a negative result identifies the parent to receive child support).
- Costs of children: Determine this using the Costs of Children tables.
- Child support amount: Multiply the child support percentage by the calculated costs of children to reach the final annual figure.
Other Child Support Assessments
For fixed and minimum assessments, parents with 2 or more assessments, or assessments for parents with second families, you may wish to discuss this with a child support lawyer.
How Calculations Work Across Australia
Child support is calculated the same way across all Australian states and territories. Our Australia child support calculator works for:
- New South Wales (NSW);
- Victoria (VIC);
- Queensland (QLD);
- Western Australia (WA);
- South Australia (SA);
- Tasmania (TAS);
- Australian Capital Territory (ACT); and
- Northern Territory (NT).
Payment Increases 2026
For assessments starting on or after 1 January 2026, several key figures have been adjusted. As a result, there has been a payment increase in 2026:
- Fixed annual rate: Increased to $1,825 per child per year for certain low-income payers without shared care.
- Minimum annual rate: Increased to $551 per year.
- Self-support amount: Increased to $31,046 per year.
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