Child Support Calculator Australia

Get a fast, private estimate based on the official Services Australia formula — before you negotiate, mediate, or speak to a lawyer.

Built by a former Department of Human Services child support officer. Calculations follow the legislated 8-step formula and are accuracy-tested against Services Australia's own estimator. See our methodology →

Free to use. Results in under 1 minute.

Based on the current Services Australia formula, including all 6 formulas.

Handles shared care, low-income cases, and scenarios the government estimator gets wrong.

No login. No account. Your numbers stay private.

Estimate your payments

What does a child support calculator do in Australia?

A child support calculator estimates the amount a paying parent owes under the formula set out in the Child Support (Assessment) Act 1989. It compares each parent's taxable income after a self-support deduction, then applies a care cost conversion to determine each parent's share of the costs of raising the child.

Care percentage thresholds

How many nights of care you provide directly affects how much child support is paid. Services Australia uses these statutory thresholds:

Care levelCare %Nights/yearCost %Payer role
Below regular care0–13%0–510%Payer only
Regular care14–34%52–12724%Payer onlynil liability possible
Shared care35–47%128–17525% +2%
per pt >35%		Income determines
the payer
48–52%176–18950%
53–65%190–23751% +2%
per pt >53%
Primary care66–86%238–31376%nil liability possiblePayee only
Above primary care87–100%314–365100%Payee only

What you'll need

  • Your adjusted taxable income (ATI) — this is your taxable income plus reportable fringe benefits, reportable super contributions, total net investment losses, total tax free pensions or benefits and any target foreign income. Your most recent tax return or a payslip estimate is a good starting point.
  • The other parent's income — an estimate is fine if you don't have the exact figure. You can adjust this later.
  • Care arrangement — what percentage of nights does each parent have the children?
  • Ages of the children — the formula uses a cost-of-children table that changes by age group.
  • Other child support obligations — if either parent has children from another relationship, that can reduce the payment amount.

Estimate vs formal assessment

What this calculator gives you

This calculator gives you an estimate based on the same formula Services Australia uses. It is useful for understanding where the numbers are likely to land — before you negotiate a private agreement, prepare for mediation, or book a lawyer.

What it does not replace

This is not a formal child support assessment. Only Services Australia can issue that. Your actual assessment may differ if either parent has income that is hard to verify, an Application for a Change of Assessment has been granted, or there is a binding child support agreement in place.

What to do with your result

If the result looks straightforward

The estimate gives you a baseline for negotiating a private agreement with the other parent, or understanding what a formal Services Australia assessment is likely to produce. You can also use the result to prepare for mediation.

If the result surprises you or your situation is more complex

Some matters go beyond what a standard estimate can cover — hidden income, disputed care arrangements, self-employment, or an existing binding agreement. If that's your situation, speaking to a family lawyer before acting on any number is worth considering.

If your income or care arrangement has changed

Run a new estimate with updated figures. If the gap between your current assessment and the new estimate is significant, a Change of Assessment may be the right next step.

Learn how a Change of Assessment works

Calculator help and references

Frequently asked questions

How much child support will I pay?

Child support in Australia is calculated using an 8-step formula under the Child Support (Assessment) Act 1989. The amount depends on both parents' adjusted taxable incomes, the percentage of time each parent cares for the children, and how many children are involved. There's no single figure that applies to everyone — the calculation varies significantly based on those inputs.

The fastest way to get your estimate is to use the calculator above. It takes the same inputs Services Australia uses and gives you a result in under two minutes. → Calculate your estimate

How is child support calculated in Australia?

Child support uses an 8-step formula. In plain terms, it works like this:

  1. Both parents' adjusted taxable incomes are assessed
  2. A self-support deduction ($31,046 in 2026) is subtracted from each parent's income
  3. The care percentage for each parent is determined
  4. The costs of raising children (from a standard table) are divided between parents based on income and care

The result is the annual child support amount. Our calculator applies this logic automatically — you enter your figures, it does the maths. For a detailed breakdown of each formula type, see our child support formula guide.

What income is used to calculate child support?

Child support uses your adjusted taxable income (ATI), not your take-home pay or gross salary alone. ATI includes:

  • Taxable income (salary, wages, business income)
  • Reportable fringe benefits
  • Reportable employer super contributions
  • Total net investment losses

It does not include Family Tax Benefit or most Centrelink payments. In 2026, a self-support deduction of $31,046 is removed from each parent's ATI before the formula is applied — only income above this threshold counts. Use your most recent Notice of Assessment from the ATO as your starting figure.

What care percentage do I need for child support to change?

Care percentage has four key thresholds in the formula:

Care % Nights/year Nights/fortnight Care level Cost %
0–13% 0–51 1 Less than regular care 0%
14–34% 52–127 2–4 Regular care 24%
35–47% 128–175 5–6 Shared care 25% + 2% per point over 35%
48–52% 176–189 7 Shared care 50%
53–65% 190–237 8–9 Shared care 51% + 2% per point over 53%
66–86% 238–313 10–12 Primary care 76%
87–100% 314–365 13–14 More than primary care 100%

Enter your exact care arrangement into the calculator to see how your cost percentage affects the payment.

How does 50/50 shared care affect child support?

Equal care does not automatically mean zero child support.

At 50/50 care, both parents are treated as sharing the costs of the children equally — but child support is still calculated based on the income difference between the two parents. The parent with the higher income typically pays the parent with the lower income, even when care is split equally.

The exact amount depends on how large the income gap is. → Calculate your 50/50 shared care estimate

What is the minimum child support payment in Australia?

There is a minimum annual child support amount that applies even if the paying parent has little or no income. In 2026, that figure is $551 — indexed each year in line with the Consumer Price Index. If the paying parent earns nothing at all, the minimum rate still applies. It is not reduced to zero. The minimum assessment reflects the expectation that all parents contribute something toward the cost of raising their children. You can use the calculator to see how payments scale from the minimum as income increases.

How much child support for one child?

The amount for a single child varies widely based on both parents' incomes and the care arrangement. As a reference: a paying parent earning $80,000 with the other parent earning $50,000 and 50/50 care would typically pay in the range of $5,000–$7,000 annually — but this is illustrative only.

The only way to get a figure that reflects your actual income and care percentage is to run the calculator. → Calculate child support for one child

Can child support be reduced if my income drops?

Yes, in some circumstances. Child support assessments are not permanent. If your income has dropped significantly since your last assessment, you may be able to apply for a Change of Assessment — a formal process through Services Australia to have your payments recalculated.

Changes are assessed against eight specific grounds set out in the legislation, including major income changes, shifts in care arrangements, school fees or medical expenses, and supporting a new family. If both parents agree on a different amount, they can also enter a binding child support agreement.

How a Change of Assessment works →