Child Support Estimator (Australia)
The 2026 basic child support formula step by step: eligibility check first, official self-support amount, care rounding and costs of the children tables built in.
Only years with a verified rule pack can be chosen. 2026 values from Services Australia (checked 2026-10-08): self-support amount $31,046.00.
1. Is this a case this estimator covers?
It covers the standard case: two parents, one case, no other dependants or cases, no non-parent carer, agreement, court order, overseas parent or care dispute, and the same care for every child. Answer each question; no amount is shown until you have.
2. Incomes and care
No names, birth dates, addresses or tax file numbers are asked for.
3. Estimate
Services Australia's official child support estimator gives the official estimate. This page shows the ordinary formula, step by step.
Answer every question in step 1 first.
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Choose the assessment year — only years with a verified rule pack are offered (2026), and no year ever falls back to another's figures.
- Answer the eligibility questions. The estimator covers the standard case: two parents, one case, no other dependants or cases, no non-parent carer, agreement, court order, overseas parent or care dispute. Anything else is explained and sent to the official estimator, with no amount shown.
- Enter both parents' adjusted taxable incomes and each child's age group and nights of care — or import the nights from the Care Percentage Calculator.
How it works
Each parent's child support income is their adjusted taxable income less the self-support amount ($31,046 for 2026), never below zero. Each parent's share of the combined figure is their income percentage.
Care is nights in care ÷ nights in the period. It is rounded under s 54D — below 50% down, above 50% up — before the official care and cost table turns it into a cost percentage. The child support percentage is income percentage minus cost percentage; the parent with a positive one pays that percentage of the costs of the children, read from the 2026 table for the number and ages of the children.
The result is the ordinary formula component. Minimum and fixed annual rates, low-care receiving rules and departures are not modelled; the page says when they could apply and links the official estimator.
Worked example
2026: incomes $100,000 and $60,000, one child under 13 with Parent B every night. Child support incomes $68,954 and $28,954 (combined $97,908), so Parent A's income percentage is 70.43%. Parent A has no care, so a 0% cost percentage. Costs of the children: $14,902 + 12c × ($97,908 − $93,137) = $15,474.52. Parent A pays 70.43% of that: $10,898.29 a year, about $419.17 a fortnight (÷ 26) for budgeting.
Tips
- Use the same nights figure Services Australia would: nights actually in each parent's care over the period.
- Every value comes from the 2026 Services Australia tables; nothing needs to be looked up.
Frequently asked questions
Is this the official assessment?
No. It is the basic formula, step by step, for the standard case. Only Services Australia makes an assessment, and its figure can differ because of minimum or fixed rates, departures, or circumstances this page screens out.
What is adjusted taxable income?
Taxable income plus items such as reportable fringe benefits, reportable super contributions, net investment losses and some tax-free pensions. It can be higher than the salary on a payslip.
Why are care and cost percentages different?
Care is the share of nights; cost is how much of the children's costs the official table treats that care as meeting. 40% care, for example, is a 35% cost percentage, and anything under 14% care counts as no cost.
Why does the official estimate sometimes differ?
Low incomes can attract a minimum annual rate, a parent with little care has specific receiving rules, and agreements, court orders and departures change the amount. None of those are applied here.
Related tools
- Care Percentage Calculator
- Nights in Care Calculator
- Parenting Nights Per Year Calculator
- Custody Nights Percentage Calculator
- Pocket Money Savings Calculator
- Conception Date Calculator
Explore more in Family, Parenting & Custody.
Cite this tool
Zerdly. (2026). Child Support Estimator (Australia). Retrieved from https://www.zerdly.com/tools/child-support-estimator-au/
Tip: Enter any known values to calculate the remaining results.
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