Child Support Calculator

Estimate your child support payments using the official Services Australia formula. Enter your details below for an instant estimate with 2026 rates.

Disclaimer: This calculator provides a general estimate only and does not constitute legal advice or an official Services Australia assessment. Actual child support may vary. Contact Services Australia or a family lawyer for a binding assessment.

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Estimate your child support

Enter both parents' details for an instant 2026-rate estimate.

  1. Parents
  2. Children
  3. Multi-case
  4. Estimate
This estimate uses the Services Australia 8-step child support formula with 2026 rates, including self-support amount, care & cost percentages, and the Costs of Children table.

Tell us about the parents

Annual taxable income and how many nights the children spend with Parent A.

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How Is Child Support Calculated in Australia?

Child support in Australia is determined by Services Australia using an 8-step formula set out in the Child Support (Assessment) Act 1989. The formula is designed to share the costs of raising children between both parents in proportion to their incomes and the time each parent spends caring for the children.

The 8-Step Child Support Formula

At a high level, the formula works as follows:

  1. Each parent's income is identified (taxable income plus certain add-backs).
  2. A self-support amount is deducted from each income (set at 1/3 of the Male Total Average Weekly Earnings figure, updated annually).
  3. The remaining child support income is combined to give a total combined child support income.
  4. Each parent's income percentage is calculated as their share of that combined figure.
  5. The cost of the children is looked up in the Costs of Children table, based on combined income and number of children.
  6. Each parent's cost percentage is determined by their nights of care, using the Care and Cost table.
  7. Each parent's child support percentage is calculated (income percentage minus cost percentage).
  8. The annual child support amount is the paying parent's child support percentage multiplied by the Costs of Children figure.

What Factors Affect How Much You Pay?

Three main factors drive the assessment: the incomes of both parents, the number of nights of care each parent provides, and the number of children in the assessment. A higher income or fewer nights of care generally results in a higher payment obligation. The number of children also increases the Costs of Children figure, though not proportionally to headcount.

Shared care arrangements can significantly reduce payments. Once a parent reaches 128 nights per year (roughly 35% care), they begin sharing the direct costs of the children, which reduces the net amount payable. At or near equal care (176 to 193 nights per year), the formula approaches a 50/50 cost split.

When Should You See a Family Lawyer?

This calculator gives a reliable estimate for straightforward situations, but a family lawyer can help if your circumstances are more complex. Consider getting legal advice if:

  • Either parent is self-employed, has business income, or receives income through a trust or company structure.
  • You want to enter into a binding child support agreement that departs from the formula assessment.
  • There has been a significant change in circumstances (job loss, new child, change of care arrangements).
  • You want to object to or appeal a Services Australia decision.
  • You have concerns that the other parent is understating their income.

You can also use our legal fees calculator to get a rough sense of what a family law matter might cost before booking a consultation.

Frequently Asked Questions

How accurate is this child support estimate?
This calculator follows the official Services Australia 8-step child support formula using 2026 rates, including the self-support amount, care and cost percentages, and the Costs of Children income table. However, it provides a general estimate only. Services Australia may adjust assessments based on additional factors such as special needs, high child-related costs, or binding child support agreements. Always check with Services Australia or a family lawyer for a binding assessment.
What's not included in this estimate?
This calculator does not account for: special needs or disability-related costs, private school fees, medical or healthcare costs, high contact costs, the cost of maintaining two homes, or binding child support agreements. It also does not include the minimum annual assessment ($551 in 2026) which may apply in low-income scenarios. For a full assessment, contact Services Australia directly.
How can I reduce my child support payments?
Child support payments can be reduced by: increasing the number of nights your children stay with you (which increases your care percentage and cost percentage), and reducing your taxable income (noting that Services Australia can use an 'income amount order' if they believe your income is not an accurate reflection of your earning capacity). You can also negotiate a binding child support agreement with the other parent, which can depart from the formula if both parties agree.
When should I see a family lawyer about child support?
You should seek legal advice if: you or the other parent have complex income arrangements (business income, trusts, investments), you are self-employed, your circumstances have changed significantly (job loss, new child, change of care), you want to enter into a binding child support agreement, you need to vary an existing assessment, or there are concerns about the other parent's earning capacity. A family lawyer can explain your options under the Child Support (Assessment) Act 1989 and help you navigate objections, appeals, and court applications.
What is the multi-case child support formula?
The multi-case formula applies when a parent has children in more than one child support case, or has relevant dependent children (RDC) living with them from another relationship. The formula adjusts each parent's child support income by deducting the Costs of Children for their RDC and other-case children before calculating the assessment. It also includes a cap: the total payable per case cannot exceed the cost of those children as if they were the paying parent's only children. This calculator supports multi-case inputs — simply check the 'Add multi-case details' box to enter RDC and other-case information.
How do nights of care affect my child support?

Nights of care directly determine the care percentage, which maps to a cost percentage through the Care and Cost table. The more care you provide, the higher your cost percentage and the lower your child support payments.

Key thresholds:

  • Below 52 nights/year (14% care) — 0% cost share
  • 52–127 nights (14–35% care) — 24% cost share
  • 128–175 nights (35–48% care) — sliding scale 25%–49%
  • 176–193 nights (48–53% care) — 50/50 cost split
  • 194–240 nights (53–66% care) — sliding scale 51%–75%
  • Above 240 nights (66%+ care) — majority or full cost shifts to you