Child Support Estimator (Australia)

Australia's child support system is administered by Services Australia under the Child Support (Assessment) Act 1989. Unlike many other countries that use flat-rate percentages, the Australian formula employs a sophisticated multi-step process that accounts for both parents' incomes, a self-support amount, the costs of raising children based on their ages, and the actual care each parent provides. This Child Support Estimator (Australia) models that formula to help separated parents understand their likely obligations before engaging Services Australia or the courts.

Step 1 — Adjusted taxable income: The formula begins with each parent's annual taxable income. From this, a self-support amount is subtracted. This self-support amount (approximately AUD 26,146 in recent years, indexed annually) represents what each parent needs to meet their own basic living costs. The remainder is the parent's income available for child support purposes.

Step 2 — Costs of children: Using both parents' adjusted incomes combined, the formula references government cost-of-children tables to determine the total estimated cost of raising the children. These tables reflect Australian Bureau of Statistics expenditure data and vary by the number of children and their age group — older teenagers (13–17) typically have higher costs attributed to them than younger children.

Step 3 — Each parent's income share: Each parent's adjusted income is expressed as a percentage of the combined adjusted income. This percentage determines each parent's share of the total costs of children, representing their theoretical obligation before care is considered.

Step 4 — Applying the care percentage: The percentage of care each parent provides directly offsets their cost liability. If a parent has 73% care, they are credited with spending 73% of the costs of children directly. The net liability is the parent's income-based share minus their care-based offset. If the result is positive, they pay; if negative, they receive.

Important nuances: The Australian formula includes minimum and maximum annual rates, Costs of Children tables that plateau at high income levels, provisions for special expenses (medical, educational), and agreement-based variations that can be registered with Services Australia. Children aged 18+ who are still in secondary education may also be included in some orders. This calculator provides an approximation; the official estimate should always be obtained through the Services Australia Child Support Estimator or a legal professional familiar with Australian family law.

Whether you are a payer trying to budget or a recipient understanding what to expect, this tool provides a transparent breakdown of each step in the Australian formula so both parties can approach discussions and negotiations with a clear understanding of the financial landscape.