A Change of Assessment is the formal process to vary a child support assessment when the standard formula produces a result that doesn't fit the family's actual circumstances. It exists because the formula — for all its careful calibration — is a one-size-fits-most calculation that can't account for unusual costs, complex incomes, or arrangements families have set up between themselves. The 10 grounds cover the main ways a "wrong" result can arise; Services Australia decides each case on the evidence both parents provide.
Either parent can apply, at any time, for free. Decisions usually land within 90 days. The downside: it's a real process with real evidence requirements — personal statements alone rarely shift the formula. This guide walks through the 10 grounds, the evidence each typically needs, and which grounds actually succeed in practice. Verified against Services Australia and the Child Support Guide §2.6.
The 10 grounds
| Reason | Grounds | Common evidence |
|---|---|---|
| 1 | High cost of spending time with or communicating with the child (long-distance contact) | Flight bookings, fuel/accommodation receipts, call records, calendar of visits |
| 2 | Special needs of the child (disability, illness, special schooling) | Medical reports, NDIS plan, school assessments, therapy invoices |
| 3 | High costs of educating the child (typically private school fees) | Enrolment letters, fee schedules, evidence of agreement to private schooling before separation |
| 4 | Child has income, assets or earnings | Bank statements, payslips, investment records for the child |
| 5 | Child receives financial support from another source (e.g. inheritance, grandparent contributions) | Trust deeds, gift records, bank trace |
| 6 | High costs of supporting children in your own care (beyond ordinary cost) | Medical bills, special-need invoices, dietary requirement evidence |
| 7 | Parent has significant financial resources beyond declared income (assets, investments, family trust distributions, partner support) | Bank statements, property valuations, trust accounts, lifestyle evidence |
| 8 | Parent's actual earning capacity differs materially from declared income | Employment history, qualifications, prior years' returns, evidence of voluntary income reduction |
| 9 | High cost of supporting another child or dependent | Centrelink statements, school fees, medical bills for the other dependent |
| 10 | Legal duty to support another child or step-child not in this case | Court orders, custody arrangements, evidence of financial support |
Try the free CS calculator → · Open the full estimator → See the standard formula result before deciding whether you need a Change of Assessment — most concerns turn out to fit within the formula, not against it. The full estimator also reads your latest assessment notice (scan it →) so you can compare formula vs notice side-by-side.
The two most-contested grounds: Reason 7 + Reason 8
These are the income-side grounds and they account for the majority of Change of Assessment applications.
Reason 7 — applies when a parent has financial resources beyond their declared income that the formula doesn't capture. Examples:
- Living rent-free in a partner's $3M home while declaring a $50k income (the housing is a "resource" even though it's not income).
- Distributions from a family trust that legitimately don't appear in personal taxable income but represent real spending capacity.
- Inherited assets being drawn down to fund lifestyle expenses (drawing down capital instead of earning income).
- Cash income or under-the-table arrangements (harder to prove, requires substantial evidence).
Reason 8 — applies when the parent's ACTUAL earning capacity differs materially from their declared income. Examples:
- Voluntarily reducing work hours after separation (formerly working 40 hours, now working 10 — and the reduction is a choice, not driven by health/redundancy/family obligation).
- Operating through a company or trust structure to retain profit instead of paying themselves market-rate wages.
- Qualifications and prior earning history far above current declared income with no good reason for the gap.
Both require substantial documentary evidence — Services Australia won't reassess on suspicion alone. The applying parent (the one alleging the income is wrong) carries the burden of proof.
What evidence helps
The pattern that works:
- Documentary, not testimonial. Receipts, statements, invoices, court orders, school enrolment letters. Not "I'm sure they earn more than that".
- Time-bounded. 12 months of bank statements beats one month. Annual cost figures beat single-instance invoices.
- Independently verifiable. Receipts from named providers (schools, airlines, medical centres) carry more weight than handwritten lists.
- Quantified. "$8,400/year in school fees" beats "very expensive school".
- Corroborated. A parent's claim of long-distance contact costs is stronger if backed by airline records AND a parenting plan AND a calendar.
Common Reason 3 (private school) outcomes
This one trips people up. Private school fees ARE NOT automatically passed on to the other parent through Change of Assessment. Services Australia considers:
- Was private schooling agreed before separation? (If both parents enrolled the child together, more likely to be included.)
- Was private schooling agreed in a parenting plan or court order post-separation?
- Is the school the child's only realistic option (e.g. specialised education for special needs)?
- Can the parent who chose the school afford their share themselves?
A parent who unilaterally enrols the child in a private school post-separation and then asks for a Change of Assessment to shift fees onto the other parent is unlikely to succeed.
The process — timeline + steps
| Step | Action | Timeline |
|---|---|---|
| 1 | Apply via myGov or paper form | Any time |
| 2 | Services Australia notifies the other parent | ~7 days |
| 3 | Other parent responds with their evidence | 14 days from notification |
| 4 | Initial review by a Services Australia officer | 30–90 days |
| 5 | Decision letter sent to both parents | At ~90 days |
| 6 | Internal review (if dissatisfied) | Apply within 28 days |
| 7 | AAT appeal (if still dissatisfied) | Apply within 28 days of internal review |
During the review, the existing assessment continues at the current amount. If the review increases the assessment, the increase may be back-dated to the application date — creating a debt covering the review period. If decreased, the difference is refunded or credited forward.
What about Departure Orders?
Some older guides reference "Departure Orders" — these are a related but separate Family Court process. Change of Assessment is the administrative process (Services Australia); Departure Orders are the court process (Federal Circuit & Family Court). Most Change of Assessment cases are dealt with administratively without going near the court. Departure Orders matter when:
- You need to depart from the formula in ways Services Australia can't (e.g. lump-sum arrangements, capital transfers in lieu of payments).
- The other parent has refused to engage with Services Australia and you need a court-enforceable order.
- You have a binding child support agreement you want changed.
The court process is significantly more expensive and slower. Most parents stick with the administrative Change of Assessment unless court involvement is unavoidable.
What to do before you apply
- Run the standard formula first — most "wrong" results turn out to be correct. Use our free CS calculator or full estimator to verify what the formula actually produces from the inputs.
- Read the relevant Reason carefully — the Child Support Guide §2.6 explains the test Services Australia applies for each ground.
- Gather documentary evidence — start the file before you apply, not after. NestWise's CS Expense Tracker helps file expense receipts as you go.
- Scan your current assessment — use the CS Assessment Scanner to extract the official figures from your notice so you can compare what Services Australia has on file vs what you think reality is.
- Consider professional advice — a family lawyer or family-finance specialist can pre-screen whether your case is likely to succeed. Many offer fixed-fee initial consultations. Services Australia decisions are reviewable but reversing a bad initial application is harder than not making it.