Child Support Calculator Australia

How to Estimate Payments

The online tool estimates payments for an individual case using the official Australian child support formula.

• Enter the requested inputs for you case.
• You can adjust the values and see how the assessment changes.
• Instantly test how income and care levels affect payments.

The estimator is accurate and produces results within 60 seconds. It was developed to make it easy for parents to estimate child support, and to see how payments are affected by income or care changes.

Including Dependent Children (Advanced Use)

You can account for dependent children by first running the calculator in a special way, then subtracting the result from the parent’s income.

A relevant dependent child is usually a biological child who lives with the parent for at least 128 days of the year and is not part of the child support assessment.

1. Enter only the dependent children in the calculator.
2. Set your care to zero and set the other parent’s income to $0.
3. Use the annual payment shown as the estimated cost of the dependent children.
4. Subtract that amount from the parent’s income, then run the normal child support estimate.

The same method can be used for either parent.

How Child Support Is Calculated in Australia

Child support is calculated in Australia by a formula that uses 3 main inputs from parents: incomes, number and ages of children, and the care percentage for each parent. The formula uses these inputs in specific ways defined by legislation.

• The incomes reported on the parents’ tax returns are adjusted, added, and compared. The formula uses incomes to assess the total amount of support required for the child, along with each parent’s individual contribution.
• The number and ages of children are used to scale the potential payment amount. For example, a second child adds between 15% and 74% to the cost of children. An only child turning 13 increases potential payments by 24.1% up to 40.6%.
• The care percentage for each parent determines how financial responsibility is allocated. The more overnights a parent has, the more they are assumed to be making a direct financial contribution. A parent with few overnights receives little credit for direct expenses and will normally be required to contribute by making payments to the other parent.

We Use the Official Formula

The online calculation 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 money
• Negative result: you receive money

Detailed Instructions (If Needed)

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 work.

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 are given higher cost weightings 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.

How to Interpret the Estimate

The estimator 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 financial 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, the tool returns the fixed annual rate of $1,825 per child per year.

The assessment applies the rule used in 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 formula continues to operate using both parents’ incomes and care levels. Shared care can produce amounts below the fixed rate, including $0. Amounts are indexed and usually change slightly each year.