Child Support Calculator
Estimate an annual child support rate using the Services Australia 8-step basic formula — self-support amount, care and cost percentages, and the Costs of the Children table.
This is an estimate of a formula assessment, not a Services Australia assessment. It covers one child support case between two parents only — see what's out of scope below.
Last relevant year's ATI - taxable income plus reportable fringe benefits, reportable super contributions, net investment losses and most tax-free pensions.
Same ATI definition as Parent A.
50.1% of nights with Parent A, 49.9% with Parent B. Common patterns: every second weekend ~52 nights/year; week-about ~183 nights/year.
The Costs of the Children table only needs the age group and count, not each exact age.
A relevant dependent child must be in that parent's care at least 128 nights a year and isn't part of another child support assessment.
Enter both parents' adjusted taxable income and the care split to see an estimate
The calculator stops where a simple estimate becomes misleading
Calculated directly
A single child support case between two parents, using the 8-step basic formula, the relevant dependent child amount, and the fixed or minimum annual rate where they apply. The same care split is assumed for every child in the case.
Directed to formal assessment
Two or more child support cases (multi-case allowance and cap), non-parent carers, different care arrangements for different children, change-of-assessment applications, court orders and binding agreements, and provisional/estimated income all need a formal Services Australia assessment.
The 8-step basic formula
Self-support amount
The self-support amount is one-third of the annualised Male Total Average Weekly Earnings (MTAWE) figure. For child support periods starting on or after 1 January 2026 it is $31,046 (annualised MTAWE $93,137). It's deducted from each parent's adjusted taxable income before their incomes are compared, so both parents keep the same amount to support themselves first.
Care and Cost table
| Care level | Cost percentage and care range |
|---|---|
| Less than regular care | 0% cost — 0–13% care (0–51 nights/year) |
| Regular care | 24% cost — 14–34% care (52–127 nights/year) |
| Shared care | 25% + 2% per point over 35% — 35–47% care (128–175 nights/year) |
| Shared care | 50% cost — 48–52% care (176–189 nights/year) |
| Shared care | 51% + 2% per point over 53% — 53–65% care (190–237 nights/year) |
| Primary care | 76% cost — 66–86% care (238–313 nights/year) |
| More than primary care | 100% cost — 87–100% care (314–365 nights/year) |
This table doesn't change with indexation — it's set in the Child Support (Assessment) Act 1989 and applies for every child support period.
Costs of the Children — children aged 0-12, 2026
| Combined child support income | 1 child | 2 children | 3+ children |
|---|---|---|---|
| $0 to $46,569 | 17c/$1 | 24c/$1 | 27c/$1 |
| $46,570 to $93,137 | $7,917 + 15c | $11,177 + 23c | $12,574 + 26c |
| $93,138 to $139,706 | $14,902 + 12c | $21,888 + 20c | $24,682 + 25c |
| $139,707 to $186,274 | $20,490 + 10c | $31,202 + 18c | $36,324 + 24c |
| $186,275 to $232,843 | $25,147 + 7c | $39,584 + 10c | $47,500 + 18c |
| Over $232,843 | $28,407 | $44,241 | $55,882 |
Separate tables apply for children all aged 13 or older (higher rates) and for children of mixed ages (a blended rate) — the calculator uses the correct table for your case. All figures are net of Family Tax Benefit and are for child support periods starting in 2026.
Fixed and minimum annual rates
Fixed annual rate — $1,825/child
Applies to a parent who didn't receive an income-support payment in the last relevant year, whose adjusted taxable income is below the Pension PP (single) maximum basic amount ($26,720 at 1 January 2026), and who has less than shared care (under 35%). Capped at 3 times the fixed rate for more than 3 children.
Minimum annual rate — $551/case
Applies when the standard formula assessment works out to less than the minimum rate and the paying parent has below regular care (under 14%) of every child in the case. A parent can apply to reduce a minimum assessment to nil in some circumstances.
What is the self-support amount for the 2026 child support period?
What are the fixed and minimum annual rates?
How does the Costs of the Children table work?
Does this calculator handle two or more child support cases?
What about non-parent carers, like grandparents?
What is a relevant dependent child amount?
Why do I need to enter nights of care rather than a percentage?
Related guides
Tax Accuracy & Sources
This calculator estimates the Services Australia 8-step basic child support formula (Formula 1) for a single case between two parents using current self-support amount, Costs of the Children table, Care and Cost table, and fixed/minimum annual rate figures. It also estimates the relevant dependent child amount. It does not model multiple child support cases, non-parent carers, differing care arrangements per child, change-of-assessment applications, court orders, binding or limited agreements, or provisional/estimated income. It is not a Services Australia assessment.