Child Support Calculator Australia

Understanding Your Result

The estimate is calculated using the legislated Australian child support formula. The calculator uses the same calculation applied by Services Australia.

You can adjust the inputs and see how the assessment changes. That allows you to test how income and care levels affect child support.

The calculator is accurate. For details of accuracy testing, see verification.

How the Calculation Works

The calculator follows the Australian Government’s 8-step child support formula. The formula compares each parent’s financial capacity with the level of care they provide.

Income
The self-support amount ($31,046 for 2026) is deducted from each parent’s taxable income. The remaining incomes are combined, and each parent’s percentage share of the total is calculated.

Care
Nights per fortnight are converted into an annual care percentage. A legislated cost table then assigns a care credit (for example, 14%–34% care equals a 24% cost credit). The care credit is offset against the income share to determine each parent’s position.

Assessment
The government cost table estimates the cost of raising the children based on the combined income. That cost is multiplied by the net position.
• Positive result: you pay child support
• Negative result: you receive child support

Using the Calculator

Your taxable income
Enter your annual taxable income. Services Australia usually uses the most recent tax return unless an income estimate is provided. Salary-sacrificed superannuation is added back for child support purposes, so reducing taxable income through super contributions does not reduce child support long-term.

Other parent’s income
Enter the other parent’s annual taxable income. The most recent recorded income is normally used, but updated estimates may later be applied and reassessed retrospectively.

Children’s ages
Enter the number of children aged 0–12 and 13–17. Teenagers attract higher cost assumptions under the government cost table. Child support normally continues until age 18 and may extend to the end of Year 12 in some cases.

Your care (nights per fortnight)
Enter the number of overnight stays in a typical fortnight. Care is calculated as a percentage derived from the 14-night cycle. For example, 50% care equals 7 nights per fortnight.

Interpreting the Result

The calculator shows the annual assessment and the equivalent monthly amount. Services Australia assesses annually but payments are usually made monthly.

The parent with greater care commonly receives child support, but a higher-income parent may still pay even with majority care.

Low income rule (2026)
If the paying parent has less than 35% care of the child and the formula calculation produces an amount below the fixed annual rate, this calculator returns the fixed annual rate of $1,825 per child per year.

This reflects the rule used in Australian child support assessments for low-income parents who are not receiving income support.

A lower minimum annual rate of $551 per year can apply if the paying parent received income support during the relevant year.

With shared care (128 nights or more per year), the fixed annual rate does not apply and the normal child support formula continues to operate using both parents’ incomes and care levels. This can produce amounts below the fixed rate, including $0. Amounts are indexed and usually change slightly each year.

Accuracy

The calculator has been compared with the Services Australia estimator and other widely used calculators. Testing confirms that the calculator above produces the same results as Services Australia, while the other calculators we tested all failed by some margin.

The calculation model and verification testing were prepared by Dr Andrew Lancaster, project lead at Child Support Australia.