Professional due diligence
This page records the official sources, calculation method, supported boundaries, implementation controls and data-handling choices behind the AusChildSupport child support Estimate.
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.
Formula selection and execution are separated into typed calculation modules rather than embedded in page copy.
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.
Shared Product Core code and dated configuration provide a route for controlled change.
01Purpose & limits
The useful question is not whether the calculator covers everything. It is whether the intended calculation and the boundary of reliance are clear.
The visitor supplies
Assessment year; children and age bands; care as nights or percentage; adjusted taxable income; 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 effective-year MAR, FAR, income-support precedence and applicable 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, relevant dependent child amount and any applicable multi-case allowance.
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 GuideWorked evidenceFormula 2 non-parent carer, single case
DSS GuideWorked evidenceFormula 3 multi-case
DSS GuideWorked evidenceFormula 4 multi-case plus non-parent carer
DSS GuideWorked evidenceFormula 5 one-parent income, overseas or non-assessable parent
DSS GuideWorked evidenceFormula 6 one-parent income, deceased parent
DSS GuideWorked evidence04Verification
Assurance is expressed through inspectable controls, not badges.
Each control below is paired with its limit.
Annual 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.
Public Formula 1–6 examples record concrete inputs, selected pathway, annual output and expanded calculation evidence.
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 treated as a Product Core 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.
06Privacy & client-data boundary
The data path changes only when a visitor deliberately chooses an additional service.
01 · Calculate
The estimate arithmetic runs in browser code and ordinary use does not require a name, email address or account. The calculator may still contact the service for product-safety availability checks and restricted operational events.
02 · Keep a copy
Download and email delivery both send the submitted calculator values to the server to generate the PDF. A download is returned to the browser; an emailed copy is sent to the address provided. The values are not stored as a Contact Request. Email delivery keeps only minimal delivery metadata without calculator values for abuse prevention and operational diagnosis.
03 · Request contact
After explicit consent and email verification, the named firm may receive the permitted Result Summary, selected structured context, safe-contact preference and contact or consent record through authenticated firm access.
Provider, retention, rights and cross-border details belong in the public privacy policy and should be read with this summary.
Inspect the AusChildSupport Privacy Policy07Firm branding & Product Core
Firm identity may frame the experience. It does not rewrite calculation meaning or remove client protections.
Firm-configurable
Controlled Product Core
What the firm is assessing
Whether this bounded Estimate journey is suitable to present under the firm’s identity, and whether its disclosures, privacy path and product governance meet the firm’s own professional and risk requirements.
What the firm is not asked to endorse
Government affiliation, a guaranteed match with a Formal Assessment, legal advice, hidden data sharing, or removal of the firm’s own conflict, engagement, privacy and professional responsibilities.
08Evaluation checklist
Review the first viewport, input journey, result explanation and firm handoff as a prospective client would.
Include standard, multi-case and non-parent-carer paths, plus a scenario the calculator should refuse to personalise.
Confirm the effective year, source register and date of the last substantive methodology review.
Trace ordinary calculation, result-summary delivery and a consented Contact Request as three separate flows.
Assess whether the Estimate, legal-advice and Services Australia boundaries are prominent enough for the firm’s audience.
Ask for targeted test evidence, source-to-rule mapping and correction or incident material relevant to your review.
Review logo, colours, copy, domain, accessibility constraints and Product Core elements that cannot be changed.
Identify internal privacy, cyber, professional-indemnity, conflict, engagement and approval requirements before launch.
Next step
A branded preview lets your firm review the calculator, Product Core boundary, privacy path and client-facing explanations in its own context. It is an evaluation artefact—not a production launch.
Hosted-firm examples are fictional demonstrations, not customer case studies or evidence of adoption.
