Child Support Change Calculator
See how changes in income, care percentage, or number of children would affect your child support assessment. Compare your current and proposed scenarios.
This calculator provides estimates only. For official assessments, use these government resources:
- Services Australia — Child Support
- Family Relationships Online — free advice, mediation referrals (1800 050 321)
- Federal Circuit and Family Court of Australia
- Legal Aid — free or low-cost legal help (available in every state)
How this calculator works
Enter your current child support scenario (incomes, number of children, ages, and care nights) and then your proposed new scenario. The calculator runs the Services Australia formula on both and shows a side-by-side comparison of the annual and fortnightly child support amounts, highlighting the dollar and percentage change so you can see exactly how the proposed change would affect your assessment.
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Frequently Asked Questions
When can I apply for a change of assessment?
You can apply for a change of assessment at any time if there's been a significant change in circumstances — such as a change in income, care arrangements, or the number of dependent children. You can also apply if you believe the formula assessment is unfair due to special circumstances.
How long does a change of assessment take?
An administrative change of assessment through Services Australia typically takes 6–12 weeks. If income details change (e.g. a new tax return is lodged), the reassessment can happen automatically within a few weeks.
Does a change in care nights automatically change child support?
Not automatically. You need to notify Services Australia of a change in care arrangements. If the care percentage changes by enough to move into a different band, your assessment will be recalculated from the date of notification.
Can child support go up and down?
Yes. Child support is recalculated whenever there's a change in either parent's income (usually when new tax returns are lodged), a change in care percentage, or a change in the number of children. It can increase or decrease depending on the circumstances.
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