Sources, scope and calculation evidence
Check the sources, supported scenarios and assumptions behind your estimate. Open the detailed records below to inspect how the calculation is maintained and tested.
The calculator is designed to help a person understand an indicative annual child support amount from the information they provide. It does not give legal advice, decide eligibility or issue an administrative assessment.
The boundary
00Evidence chain
Each link answers a different question. Official material establishes the rule; implementation and testing determine whether the product applies it as intended.
The Act, DSS Guide and Services Australia material define the governing rule and administrative explanation.
Annual parameters are held by assessment year with source, effective-period and review metadata.
The calculator applies the rules to the information entered; page explanations describe those calculations.
Automated tests exercise formula paths, annual values, care rounding, rate rules, caps and unsupported states.
The result identifies the formula pathway, confirmed inputs, calculated steps, assumptions and reliance boundary.
The same calculation rules and dated annual settings are maintained across public and firm-branded calculators.
01Purpose & limits
Check that your circumstances fall within the supported scope before relying on a figure.
The visitor supplies
Assessment year; children and age bands; care as nights or percentage; adjusted taxable income (taxable income plus certain other amounts, such as reportable fringe benefits); relevant dependent children; children in other assessments; and, where relevant, income-support and non-parent-carer context.
The calculator derives
Care and cost percentages, child support income, combined income, income percentages, child support percentages, Costs of Children, formula pathway, rate treatments, caps and payment direction.
The result represents
An indicative annual amount and convenient payment cadences, with the pathway, confirmed inputs, calculation steps and caveats shown for review.
| Coverage area | Current treatment | Reliance boundary |
|---|---|---|
| Standard two-parent cases | Formula 1 sequence, including child-specific care and the effective-year Costs of Children table. | The result depends on complete and correctly characterised inputs. |
| Non-parent carer cases | Formula 2, including eligible carer care and allocation between recipients. | The calculator does not decide whether an application or person is legally eligible. |
| Multiple child support cases | Formula 3 and 4 paths, relevant dependent child amounts, multi-case allowances, same-age costs and caps. | Other assessments must be entered accurately; interacting periods or official records may require Services Australia. |
| One-parent income assessments | Formula 5 and 6 paths for bounded non-parent-carer scenarios. | No personalised result is produced where assessment scope, jurisdiction or assessed-parent status remains unconfirmed. |
| Minimum, fixed and capped rates | The applicable minimum and fixed annual rates, income-support precedence and multi-case caps are implemented. | Entitlement, exemptions, accepted estimates and official administrative decisions are not made by the calculator. |
| Outside the Estimate | Private agreements, court orders, objections, departures or change of assessment, enforcement, arrears and past obligations are not resolved. | Use Services Australia for a Formal Assessment or official action; obtain professional advice where legal consequences may follow. |
02Source register
Primary authority is separated from supporting explanation. AusChildSupport’s implementation is not itself an authority.
| Subject | Authority | Source or instrument | What it governs | Effective period | Methodology reviewed |
|---|---|---|---|---|---|
| Governing legislation | Commonwealth of Australia | Child Support (Assessment) Act 1989 — compilation 71 (C2026C00269) | The legislative basis for administrative assessment, formula structure and defined concepts. | Compilation 71, in force 1 July 2026 | 13 August 2026 |
| Formula pathways 1–6 | Department of Social Services | Formula 1Formula 2Formula 3Formula 4Formula 5Formula 6 | Which statutory method applies and the additional steps for non-parent-carer, multi-case and one-parent assessments. | Guide version 5.00, released 1 July 2026 | 13 August 2026 |
| Annual formula values | Department of Social Services | Department of Social Services Child Support Guide 2.3.2 Current formula values | DSS Guide version 5.00, released 1 July 2026, supplies operational explanation for the annual values; the registered Notice controls the values and COTC table where they differ. | Guide version 5.00, released 1 July 2026; child support periods starting in 2026; Ticket 01 resolution; ADR-0110 | 13 August 2026 |
| Costs of Children | Department of Social Services | Registered 2026 Costs of the Children Table Notice | The Notice sets MTAWE at $93,137. Bands are the statutory 0.5–2.5 MTAWE thresholds rounded to whole dollars; COTC bases and caps are transcribed from the registered table. | Registered Notice C2025G00638; child support periods starting in 2026; Ticket 01 resolution; ADR-0110 | 13 August 2026 |
| Subject | Authority | Source or instrument | What it governs | Effective period | Methodology reviewed |
|---|---|---|---|---|---|
| Eight-step explanation | Services Australia | Basic child support formula | Plain-language sequence and care-and-cost explanation. It is corroborative only; the 2026 Costs of Children values use the registered Notice above. | Page updated 1 January 2026 | 13 August 2026 |
| Care evidence and percentage | Services Australia | How percentage of care affects child support | How care is considered and the evidence Services Australia may seek where care is disputed. | Current administrative guidance | 13 August 2026 |
| Guide change monitoring | Department of Social Services | Child Support Guide updates — 2026 | Published changes to formula terms, annual tables and related administrative guidance. | 2026 update register | 13 August 2026 |
The methodology review date records when the links and stated source details were inspected for this page. It is not a legal opinion about every possible application of the source material.
03Calculation method
The core pathway follows the official eight-step structure.
Adjusted taxable income less the self-support amount (set aside for the parent’s own support), relevant dependent child amount and any applicable multi-case allowance (recognising the costs of children in other child support cases).
The parents’ child support incomes are combined for the case.
Each parent’s share of the combined child support income is calculated.
Entered care is converted to a percentage and rounded using the statutory care method.
The care percentage is mapped to the official care-and-cost table.
Cost percentage is subtracted from income percentage for each child.
The effective-year table is applied by income band, child count and age grouping.
A positive child support percentage is applied to the relevant child cost, then allocation, minimum or fixed rate and cap rules are applied where relevant.
Effective-year register
These values apply to child support periods starting in 2026. They are read from the same year-keyed configuration used by the calculator.
The additional pathways cover bounded non-parent-carer, multi-case and one-parent income scenarios. Rounding is applied at the encoded operation boundaries rather than only at final display.
Formula 1 basic two-parent cases
DSS GuideRecorded exampleFormula 2 non-parent carer, single case
DSS GuideRecorded exampleFormula 3 multi-case
DSS GuideRecorded exampleFormula 4 multi-case plus non-parent carer
DSS GuideRecorded exampleFormula 5 one-parent income, overseas or non-assessable parent
DSS GuideRecorded exampleFormula 6 one-parent income, deceased parent
DSS GuideRecorded example04Verification
Automated checks and fictional examples help inspect the calculation. They do not establish independent assurance or live service operation.
Open the Formula 1–6 worked examples for fictional cases evaluated by the current calculator. Their fixed inputs differ from the maintained fixtures below.
Other Parent pays You (Parent) $862 per year. Rounded whole-dollar obligations from the maintained fictional fixture.
Compare an example with different inputsYou (Parent) pays Non-Parent Carer $7,185 per year; Other Parent pays Non-Parent Carer $862 per year. Rounded whole-dollar obligations from the maintained fictional fixture.
Compare an example with different inputsOther Parent pays You (Parent) $1,189 per year. Rounded whole-dollar obligations from the maintained fictional fixture.
Compare an example with different inputsYou (Parent) pays Non-Parent Carer $6,204 per year; Other Parent pays Non-Parent Carer $1,189 per year. Rounded whole-dollar obligations from the maintained fictional fixture.
Compare an example with different inputsYou (Assessed Parent) pays Non-Parent Carer $7,705 per year. Rounded whole-dollar obligations from the maintained fictional fixture.
Compare an example with different inputsYou (Assessed Parent) pays Non-Parent Carer $8,569 per year. Rounded whole-dollar obligations from the maintained fictional fixture.
Compare an example with different inputsAnnual configuration records official source links, effective dates and review dates; formula metadata links each path to the relevant DSS Guide section.
Does not proveIt does not establish that an external lawyer or government body has approved the interpretation.
Automated domain tests cover care rounding, income components, annual values, minimum and fixed rates, multi-case caps and formula-specific boundaries.
Does not provePassing tests cannot cover every factual combination or prevent an incorrect test expectation.
Maintained fictional fixtures and the worked-examples page are evaluated by the current calculator. They use different fixed inputs; the worked-examples page also compares three DSS guide examples using the guide’s own assessment years.
Does not proveThese examples are product evidence, not official Services Australia assessments or independent validation.
Dedicated rounding utilities and pathway tests check the points at which statutory amounts, percentages and allocations are rounded.
Does not proveThey do not resolve ambiguity where the governing material itself requires interpretation.
Validation blocks a personalised one-parent Estimate when country, assessment scope, assessed-parent status or qualifying carer care is unresolved.
Does not proveA block is a safety boundary; it does not determine legal eligibility.
The result records confirmed inputs, formula pathway, income and care steps, assumptions, limits and the Estimate boundary.
Does not proveAn explanation cannot reveal facts the visitor did not enter or replace professional review.
The shared calculator has keyboard, semantic, mobile and reduced-motion test coverage; accessibility is a shared calculator requirement.
Does not proveNo formal WCAG conformance claim or independent accessibility audit is made here.
Claims deliberately not made
government approval · legal advice · independent verification · guaranteed agreement with a Formal Assessment · formal accessibility or security certification · error-free operation.
05Annual source updates
Annual settings are tied to dated source records, effective periods and a scheduled review date.
What is checked
Review the Guide change register, annual values, Costs of Children table and relevant Act compilation.
Identify the affected assessment year, formula path, parameter or public explanation.
Change the effective-dated configuration or calculation module, retaining source metadata beside annual values.
Run affected domain tests and regression checks, inspect representative formula evidence and review public explanations.
Keep the source identity, effective dates and next review date beside the annual settings they support.
This record describes repository configuration and review dates. It does not prove that a future review, publication, deployment or independent review has occurred.
06Data handling
The estimate is calculated in your browser. Saving or emailing a summary sends calculation information to our server; a firm Contact Request requires separate consent and verification.
See what happens to your information, including the limits of the available security evidence. The Privacy Policy holds the detailed collection, retention and rights information.
Continue your review
Firm branding does not change the calculation rules. For the client journey, firm responsibilities and commercial terms, return to the firm evaluation page.
Worked examples are fictional demonstrations, not official assessments, independent validation or evidence of customer adoption.