How is child support calculated in Australia?

Services Australia uses an 8-step formula: each parent's adjusted taxable income less a self-support amount ($31,046 in 2026) gives their child support income. Each parent's share of the combined income, minus the share of costs they already meet through care, gives their child support percentage. The positive percentage is multiplied by the legislated costs of the children to get the annual payment.

How do care nights change child support?

Care is converted to a cost percentage: below 14% of nights recognises no costs, 14–34% recognises 24%, then a sliding scale applies through shared care, 76% for primary care and 100% above 86% of nights. More care means a bigger credit against your income share, so your payment falls.

What is the minimum child support payment in 2026?

Parents on income support with less than shared care generally pay the minimum annual rate of $551 per year in 2026. Parents who report very low income but don't receive income support pay the fixed annual rate of $1,825 per child (up to 3 children) instead.

Is there a cap on child support income?

Yes. Combined child support income above 2.5 times annualised MTAWE — $232,843 in 2026 — is ignored, which caps the costs of the children and therefore the maximum assessment.

Is this calculator an official Services Australia assessment?

No. It applies the published basic formula and 2026 values to the details you enter. Actual assessments can differ — relevant dependant children, multiple cases, non-parent carers, agreements and change-of-assessment decisions all change the result.

§ — Family

How much child support will be paid?

Enter both parents' incomes, your share of care and your children's ages to estimate child support under the Services Australia basic 8-step formula — who pays, and how much per week, fortnight and year, using 2026 rates.

2026 rates·Source: Services Australia·Read · 5 min

Your details

Your adjusted taxable income

Other parent's adjusted taxable income

Children aged 0–12

Children aged 13+

Your share of care (% of nights)

≈ 110 nights a year. Every second weekend ≈ 14%, week on / week off = 50%.

You receive income support (e.g. JobSeeker)

Other parent receives income support

Your estimate · 2026 rates

You pay, per fortnight

$219

$5,710 a year, $476 a month, or $110 a week — based on the basic 8-step formula.

Your child support income$53,954

Other parent's CS income$23,954

Your income % / cost %69.3% / 24%

Costs of the children · per year$12,618

Annual transfer$5,710

2026 formula values

Step	Value
Self-support amount deducted from each income	$31,046
Combined child support income	$77,908
Your child support % (income % − cost %)	45.3%
Combined income cap (2.5 × MTAWE)	$232,843

Source: Services Australia · 2026 calendar year, effective 1 January 2026

How the 8-step formula works

The formula starts with each parent's adjusted taxable income, less a self-support amount of $31,046(one third of annualised male total average weekly earnings, or MTAWE). What remains is each parent's child support income.

Each parent's share of the combined child support income is their income percentage. From it, the formula subtracts a cost percentage— the share of the children's costs a parent already meets directly through care. A parent with every-second-weekend care (14–34% of nights) is credited with meeting 24% of costs; equal care is credited with 50%.

The parent whose income share exceeds their cost share pays the difference — their child support percentage — multiplied by the legislated costs of the children, which depend on combined income, the number of children and whether they are under or over 13.

Combined income above $232,843 (2.5 × MTAWE) is ignored, which caps the assessment no matter how much the higher earner makes.

Care % of nights → cost % credited

Care	Nights / year	Cost %
0–13%	0–51	0%
14–34%	52–127	24%
35–47%	128–175	25% + 2/pt
48–52%	176–189	50%
53–65%	190–237	51% + 2/pt
66–86%	238–313	76%
87–100%	314–365	100%

Source: Child Support (Assessment) Act 1989 · s55C

What the children cost, according to the law

The Costs of the Children table in the Child Support (Assessment) Act works like tax brackets: a percentage applies to each slice of combined child support income, in bands of half MTAWE ($46,569 each in 2026), up to the 2.5 × MTAWE cap.

Costs rise with the number of children (capped at three) and with age — teenagers cost more. One child under 13 costs 17 cents of every dollar in the first band; a teenager costs 23 cents. When a family has children in both age groups, the table averages the two rates.

Two low-income safeguards sit under the formula in 2026: parents on income support with less than shared care generally pay the minimum annual rate of $551, and parents who report very low income without income support pay the fixed annual rate of $1,825 per child (up to three children).

This calculator covers the basic formula only: two parents and children of one relationship. Relevant dependant children from other relationships, multiple child support cases, non-parent carers and private agreements all change the assessment — and only Services Australia can make one. Child support values are indexed each 1 January, unlike most benefits.

2026 formula values

Value	2026
Annualised MTAWE	$93,137
Self-support amount	$31,046
Combined income cap	$232,843
Minimum annual rate	$551
Fixed annual rate (per child)	$1,825

Source: Services Australia · effective 1 January 2026

Sources

Services Australia (servicesaustralia.gov.au) — basic child support formula, fixed and minimum assessments, 2026 values
DSS Child Support Guide — formula tables and values (guides.dss.gov.au)
Child Support (Assessment) Act 1989 — Schedule 1, Costs of the Children table
Data last verified: July 2026

§ Letters & replies

Child support, answered.

Common questions about how the Australian child support formula works.

Which income does the formula use?+ open

Adjusted taxable income — taxable income plus reportable fringe benefits, reportable (salary-sacrificed) super, net investment losses, certain tax-free pensions and foreign income. It's usually the previous financial year's figure, and it's often higher than salary alone.

Why does 14% of nights matter so much?+ open

52 nights a year — roughly every second weekend — is the "regular care" threshold. Below it, a paying parent is credited with none of the children's costs; at or above it, they're credited with 24%, which cuts the payment noticeably. It's the biggest single step in the care table.

Does 50/50 care mean no child support?+ open

Not necessarily. Equal care credits each parent with 50% of costs, but if one parent earns more, their income share exceeds 50% and they still pay the difference. Only equal care and equal child support incomes produce a nil assessment.

What if the paying parent has children from a new relationship?+ open

A "relevant dependant child allowance" is deducted from that parent's income before the formula runs, and parents with multiple child support cases get a multi-case allowance. Both reduce the assessment — this calculator doesn't model them, so treat its result as an upper-bound estimate in those situations.

Can parents agree on a different amount?+ open

Yes. Limited and binding child support agreements can replace the formula amount, and either parent can apply for a change of assessment in special circumstances — for example where a parent's earning capacity, property or the cost of seeing the children differs from what the formula assumes.

Is this an official assessment?+ open

No. It's an estimate using the published basic formula and 2026 values. Only Services Australia can make an assessment, and it will use verified incomes, actual care determinations and any allowances that apply to your case.

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