Child Support Assessments and Private Agreements in Australia

How an Administrative Assessment Is Calculated

Several statutory formulas apply to different family structures. In the usual formula, the sequence is:

1. work out each parent's adjusted taxable income;
2. deduct the indexed self-support amount, then any relevant dependent child amount and multi-case allowance, to reach child-support income;
3. combine the parents' child-support incomes and calculate each income percentage;
4. determine care percentage and convert it to statutory cost percentage;
5. subtract cost percentage from income percentage to obtain child-support percentage;
6. apply the positive percentage to the costs of the child or children from the statutory table; and
7. apply minimum-rate, fixed-rate, multi-case-cap and other rules where relevant to reach the annual rate.

Adjusted Taxable Income, Business Income and Estimates

Adjusted taxable income is broader than taxable income. Its statutory components can include taxable income, reportable fringe benefits, reportable employer superannuation contributions, total net investment losses, specified tax-free pensions or benefits and foreign income. Where a tax return is outstanding, the Registrar may use provisional income under the statutory method.

Self-employment requires careful analysis. Business turnover is not automatically the parent's income; equally, wages or taxable distributions may not reveal all income, earning capacity, property or financial resources. Company or trust control, drawings, retained earnings, loans, personal expenses, salary sacrifice and restructuring can matter. Accounting treatment is evidence, not necessarily the end of the statutory enquiry.

An estimate can generally be elected where the estimated adjusted taxable income for the relevant year is at least 15% below the income being used and eligibility and timing rules are met. It must be reasonable and updated if circumstances change. Reconciliation against actual income can produce arrears, overpayments and an estimate penalty. A voluntary reduction may separately raise earning-capacity issues in a change-of-assessment process.

Care Percentages and Changes in Care

Services Australia ordinarily works from nights of care, or equivalent care where nights do not fairly describe the arrangement, then converts the percentage to a statutory cost percentage. The broad bands are below regular care (0–13%), regular care (14–34%), shared care (35–65%), primary care (66–86%) and more than primary care (87–100%). A parenting order or plan is relevant evidence, but the care recognised for child support depends on the statutory rules and actual circumstances.

Notify a change promptly. If told within 28 days, the new percentage can generally apply from the change date; later notification can limit retrospectivity and cause debt or overpayment. Where care is disputed or a written arrangement is not followed, interim rules may apply while the dispute is resolved. Parenting enforcement belongs in the parenting-law process, not in the child-support account.

Changing an Assessment in Special Circumstances

Sections 98C and 117 organise the ten reasons. In concise terms they concern:

1. high costs of enabling a parent to spend time or communicate with the child;
2. special needs of the child;
3. high costs of caring for, educating or training the child in the manner intended by the parents;
4. the child's income, earning capacity, property or financial resources;
5. payments, transfers or property made for the child's benefit;
6. high childcare costs for a child under 12;
7. necessary expenses affecting a parent's capacity to support the child;
8. either parent's income, earning capacity, property or financial resources;
9. a parent's legal duty to maintain another person; and
10. a parent's responsibility to maintain a resident child in the defined statutory circumstances.

A listed reason is only the gateway. There must be special circumstances, and the result must be just and equitable as between the child, payer and payee and otherwise proper. The Registrar may initiate a change in defined circumstances. A decision may increase or decrease liability. Retrospective periods are restricted and a court's leave may be required for an older period.

Evidence, Disclosure and Preparation

An application should identify the statutory reason, the period and result sought, and connect each factual assertion to evidence. Depending on the issue, records may include tax returns, financial statements, trust deeds, bank and loan records, school invoices, medical or allied-health reports, childcare accounts, travel evidence and care calendars. Unsupported suspicion of hidden income is not enough, and tax returns alone may not resolve a controlled-business case.

The other party generally receives the application and supporting material and may respond. Statutory confidentiality and safety controls apply, but unnecessary addresses, contact details and third-party information should not be included. Raise a safety concern before lodging. A professional report may be needed to establish a claimed special need and its cost.

Objections, ART Review and Court Pathways

1. Objection: lodge written grounds and evidence with Services Australia, ordinarily within 28 days after notice of the decision, or 90 days if residing overseas in a reciprocating jurisdiction. A late objection needs an extension request.
2. ART review: an eligible person dissatisfied with a reviewable objection decision may seek merits review by the Administrative Review Tribunal, ordinarily within 28 days after notice of the objection decision, or 90 days if residing overseas in a reciprocating jurisdiction. An extension may be available.
3. Court: a question-of-law appeal from an ART decision may be available. Courts also have separate statutory roles in departure orders, agreement set-aside applications, parentage and enforcement.

Care-percentage decisions have special objection and ART date-of-effect rules. The usual ART time restriction does not apply to them in the same way, although delay can affect the operative date. An objection or ART application does not itself suspend the operative decision or liability. Read the notice immediately, keep paying or seek advice about the account, and distinguish a court departure order changing an assessment from a departure prohibition order restricting overseas travel for debt.

Limited and Binding Child Support Agreements

Limited agreements

A limited agreement must be written, signed and accepted by the Registrar. An administrative assessment must be in force, and the agreement's annual rate must be at least the assessed rate when accepted. Independent advice is not mandatory, although advice may be prudent. Services Australia issues notional assessments, including for Family Tax Benefit purposes.

A limited agreement can end by written agreement, replacement with another qualifying agreement, court order, a party's written election after three years, or a qualifying notional-assessment change. The 15% route is not triggered by every movement: the notional assessment must differ by more than 15% from the previous one in circumstances not contemplated by the agreement, subject to the statutory mechanism. Loss of eligible-carer status can suspend and ultimately terminate an agreement under the Act.

Binding agreements

A binding agreement generally does not require an existing assessment and may provide more or less than the formula. Before each party signs, that party must receive independent legal advice about the agreement's effect on their rights and its advantages and disadvantages at that time. The agreement requires the statutory statements and signed adviser certificates, a signed original or copy must be given to each party, and Registrar acceptance is required.

Section 80CA prevents a binding agreement from simply being varied. A change ordinarily requires effective termination and replacement. Later changes in income, care, school fees or circumstances do not automatically rewrite it. Advice and acceptance do not make an agreement immune from challenge, and drafting shortcuts can invalidate or destabilise it.

What a Proposed Agreement Should Address

• periodic amount, frequency, due dates, indexation and any review formula;
• school choice and fees, medical, dental, allied-health, insurance and extracurricular costs;
• consultation or consent before costs are incurred, invoices, proof and reimbursement periods;
• scholarships, rebates, insurance recoveries and changes in care or residence;
• travel or overseas costs where relevant;
• the relationship with an assessment, notional assessments and Family Tax Benefit;
• collection method, arrears, default, enforcement, duration, terminating events and dispute resolution.

This is an issue list, not a clause bank. The legal effect depends on precise drafting and the statutory category.

Periodic, Non-periodic, In-kind and Lump-sum Support

Periodic support is different from non-periodic school or medical costs, benefits in kind and a statutory lump-sum credit. A non-periodic provision should say whether and how it reduces the annual rate. A voluntary payment to a school, landlord or supplier may not reduce a registered debt.

A lump-sum credit under section 84(1)(e) requires a binding agreement, an administrative assessment in force, and the statutory minimum value. The crediting percentage and indexation affect how the lump sum is exhausted. Property transfers and property settlement do not automatically discharge child support; obtain family-law, tax and financial advice before using capital for long-term support.

Changing, Suspending, Terminating or Setting Aside an Agreement

These are different legal events. An agreement may end by a qualifying termination agreement, replacement, an express end date or another statutory event; eligible-carer changes may suspend or terminate it. Binding agreements cannot simply be varied. Section 136 permits a court to set aside an agreement on defined grounds, including fraud or failure to disclose material information, undue influence or unconscionable conduct. A limited agreement has additional grounds involving a significant change in circumstances; a binding agreement has a distinct ground where exceptional circumstances arising since it was made would cause the applicant or a child hardship if it were not set aside. The precise ground and remedy must be pleaded and proved. Regret, a poor bargain or an ordinary later change does not itself establish a ground.

Collection Choice, Family Violence and Enforcement

With Private Collect, parents manage transfers and records. With Child Support Collect, Services Australia collects registered liabilities. The choice can affect Family Tax Benefit Part A and how far privately unpaid amounts can later be recovered; parents should not assume every private shortfall will be collected retrospectively. Keep bank records and payment descriptions, and do not rely on cash without receipts.

Private collection or direct negotiation may be unsafe where family violence, coercion or systems abuse is present. Services Australia can discuss collection arrangements and social-work support. Manage addresses and disclosure carefully and seek advice before negotiating. For immediate danger call 000; 1800RESPECT provides national support.

Collection tools include employer withholding, tax-refund interception, garnishee or third-party recovery, litigation and private enforcement where legislation permits, penalties and interest in applicable cases, and reciprocal-jurisdiction measures. A departure prohibition order can prevent overseas departure in a qualifying debt case until revoked or an authorisation certificate is issued.

When Child Support Ends

Common terminating events include the child turning 18, death, adoption, the child becoming a member of a couple, and specified residence or eligible-care changes. Reconciliation is different. Liability between the reconciled parents may initially be suspended under the statutory process, but that suspension does not apply to child support payable to a non-parent carer. If the parents remain reconciled continuously for six months, reconciliation generally becomes a terminating event for the administrative assessment. Reconciliation and any later separation should be reported promptly. The precise Act provision and any agreement must be checked. Under sections 151B–151E, an eligible payee can apply before the child turns 18 to continue an assessment to the end of the secondary-school year in which the child turns 18. Late applications are confined to the statutory exceptional circumstances.

Adult child maintenance for education or disability under the Family Law Act 1975 (Cth) is separate. Our guide to when financial responsibility ends addresses that pathway in detail.

Related Family-law Rules and International Cases

Parenting time and child support are legally distinct: non-payment does not ordinarily justify withholding a child, and failure to facilitate time does not automatically extinguish support. See the parenting orders guide. Property settlement does not automatically determine child support; see the property settlement guide. Child support is also separate from spousal maintenance. Periodic child support is generally neither deductible to the payer nor taxable income of the recipient.

Reciprocating-jurisdiction cases can involve eligibility, overseas registration and collection, foreign income and currency evidence, and the longer objection period. Not every country is covered. Obtain advice early before relocation; the detailed relocation issues remain in our relocation guide.

Practical Checklists

Reviewing an assessment

• check parent, child, period and care details;
• compare ATI components with current source records;
• check dependent-child and multi-case treatment;
• record actual care and notify changes promptly;
• read the reasons, objection rights and deadline.

Preparing a change or objection

• identify the decision, statutory reason, period and outcome sought;
• prepare a chronology and calculations;
• collect only relevant financial, care and expense evidence;
• obtain professional reports where necessary;
• remove unnecessary sensitive details and raise safety concerns;
• lodge within time and retain proof.

Before signing an agreement

• confirm whether limited or binding is intended and whether an assessment is required;
• model payments, indexed changes, notional assessments and Family Tax Benefit;
• define expenses, approvals, evidence, payment dates and default;
• test changes in income, care, school and residence;
• understand duration, termination, enforcement and dispute provisions;
• for a binding agreement, ensure each party obtains genuinely independent legal advice before signing—and consider advice before committing commercially in any case.

Frequently Asked Questions

Official Sources

• Child Support (Assessment) Act 1989 (Cth) — current authorised compilation.
• Child Support (Registration and Collection) Act 1988 (Cth) — current authorised compilation.
• Family Law Act 1975 (Cth).
• Services Australia — Child Support.
• Department of Social Services — Child Support Guide.
• Administrative Review Tribunal — Child support reviews.
• Federal Circuit and Family Court of Australia — Child support applications.

How Parke Lawyers Can Help

Parke Lawyers can draft or advise on limited and binding agreements, review an agreement proposed by the other parent, prepare complex change-of-assessment matters involving businesses, trusts, resources or earning capacity, conduct objections and ART reviews, advise on setting aside and enforcement, coordinate child support with property settlement, and manage collection issues involving family violence or financial abuse. Services Australia remains the appropriate contact for routine calculations and account administration.