How to Use the Calculator
Watch this short walkthrough showing how to enter your income, children, and care details to calculate accurate payments or receipts.
The calculator has been running reliably since 2017 and follows the same method used by Services Australia.
Accuracy statement
This calculator applies the official child support formula used by Services Australia. Results are typically identical to official assessments when the same inputs are entered. Small differences can occur if government parameters have been recently updated or if a case involves multiple families or non-standard circumstances.
How the estimate is calculated
This calculator applies the formula in the Child Support (Assessment) Act 1989 and the government’s Costs of Children Table. Results depend on both parents’ taxable incomes, the number and ages of children, and care percentage (nights per fortnight).
More nights generally reduce what you pay or increase what you receive. Minimum and fixed rates, income caps, and adjustments for additional dependants may also apply. The tool handles single-family cases only.
How Child Support Works in Australia
How Australia’s child support system operates under the official formula. This video covers the income-sharing method, cost tables, and why the current model assumes spending patterns from intact families.
Although recorded several years ago, the explanation remains accurate and reflects how the Child Support Scheme still works today. It was produced by Dr Andrew Lancaster (PhD Economics, ANU), founder of Child Support Australia.
Low-Income Payers
Low-income payers pay relatively small amounts of child support. For those with less than shared care (fewer than 5 overnights per fortnight), a fixed rate applies. This is set to $1,831 per child per year (2025 rate), capped at three children.
However, if you recently received income support, a $534 minimum annual rate applies. If you also have at least regular care (at least 2 nights per fortnight), you can apply to have the payment reduced or waived.
Care Percentage Calculator
Use our care percentage calculator to get a detailed estimate of child support. The calculations are generally consistent whether you use care percentage or nights per fortnight. However, especially with shared custody, holidays or schedule changes can affect the final payment. You need the care percentage to account for holidays and other disruptions.
FAQ: How much child support will I pay if I make $100k?
If you make $100k per year in Australia, child support payments generally fall between $11.6k and $22.6k annually. This assumes no visitation. The exact amount depends on the number of children, their ages, and how much time they spend with you. Fewer children and more time with them lead to lower payments.