With 50/50 care in NSW, the higher-earning parent usually still pays child support. Equal nights give both parents a cost percentage of 50%, which takes care out of the equation and leaves income to decide the outcome. The wider the income gap, the larger the payment.
Most parents reach that conclusion the hard way, after assuming an equal arrangement would balance itself. The Services Australia formula has two moving parts. Equal care neutralises one and does nothing at all to the other.
That does not put the assessment beyond challenge. Ten defined grounds exist for changing it, and a few of them come up constantly in shared care matters where a tax return tells only part of the story.
Key takeaways
- Child support with 50/50 care is calculated on the income gap between parents, because equal care sets both cost percentages at 50%.
- Two nights a fortnight is 14% care, which is the threshold for regular care and the first point at which the formula gives any credit for time.
- The assessment covers a general contribution to raising the child. School fees, braces and sport are not itemised in it.
- Services Australia, not the court, runs child support in almost every matter. A court departure order under section 118 exists but sits well outside the ordinary path.
Do you pay child support if you have 50/50 custody?
Yes, in most cases where incomes differ. The formula treats care and income separately, then compares them.
Each parent’s adjusted taxable income is reduced by a self-support amount, which is a fixed figure set annually to cover that parent’s own living costs. What remains is their child support income. The two figures are added together, and the combined total is run against the Costs of the Children table to produce an estimated annual cost of raising your children at that income level and those ages.
From there, each parent has an income percentage, being their share of the combined child support income. They also have a cost percentage, drawn from their care. Subtract the second from the first. A positive result means you pay. A negative one means you receive.
At exactly equal care, both cost percentages are 50%. So a parent contributing 65% of the combined income has a child support percentage of 15%, and pays 15% of the assessed cost of the children to the other household. Equal nights do not erase that. They only stop care from adding to it.
How is child support calculated with shared care?
The care percentage is where most of the confusion sits, because the bands are fixed and the jump between them can be sharp.
Care percentage | Nights per year | Band | Cost percentage |
0 to 13% | 0 to 51 | Below regular care | 0% |
14 to 34% | 52 to 127 | Regular care | 24% |
35 to 47% | 128 to 175 | Shared care | 25% to 49% |
48 to 52% | 176 to 189 | Equal care | 50% |
53 to 65% | 190 to 237 | Shared care | 51% to 75% |
66 to 86% | 238 to 313 | Primary care | 76% |
87 to 100% | 314 to 365 | Above primary care | 100% |
Anything between 48% and 52% is treated as equal. A week-on, week-off arrangement, a 5-2-2-5, a fortnightly rotation with a midweek night: all of them land in the same band and produce the same cost percentage, whether the nights were agreed between you or decided by a court. Parents who have negotiated hard over a single night are sometimes deflated to learn the formula cannot see it.
Two nights a fortnight works out at 52 nights a year, which is 14% care. That is the first threshold that registers, and it carries a flat 24% cost percentage. Below it, time contributes nothing to the calculation.
The Services Australia child support estimator applies all of this in a few minutes. Run it before mediation, before you form a view about what is fair, and before the other parent’s lawyer runs it for you.
What does child support cover in 50/50 custody?
Nothing specific, which is the honest answer and the one that frustrates people most.
The assessment is a transfer of money toward the general cost of raising a child. Food, clothing, housing, utilities, ordinary medical care, school supplies. It is not itemised, not accounted for, and the receiving parent does not have to account for how it is spent. There is no mechanism in the assessment for splitting an orthodontist’s bill or a Year 9 camp.
Private school fees are the recurring flashpoint in Sydney matters, and they sit outside the assessment unless something is done about it. Same with extraordinary medical costs, elite-level sport, and instrument tuition at a serious standard.
Which brings up a pattern we see often. One parent, usually the higher earner, pays the assessment and then voluntarily covers half of school fees, half of activities, half of the gap fees at the GP. They assume the 50/50 in the care arrangement carries over to expenses. It does not. Those payments are gifts in the eyes of the scheme unless they are captured in a written agreement or a change of assessment decision, and years of them can be made without either parent realising the arrangement was never binding on anyone.
Get the extras written down early. School fees and who signs the enrolment form, uniforms, camps, extracurriculars, travel, medical gaps, who holds the passports. A parenting plan can record it, though only consent orders or a child support agreement make it enforceable.
What parents assume, and what the scheme does
The assumption | What happens |
50/50 care means no child support | Care is one input. Income is the other, and it decides the result |
A court will order more than the assessment | Services Australia administers child support. Courts have a narrow departure power, rarely used |
Extras split 50/50 because care does | Extras are outside the assessment entirely unless agreed or ordered |
Child support and property settlement are one negotiation | Separate processes, separate law. Property settlement runs under section 79 of the Family Law Act 1975 |
Once Services Australia is involved, you cannot go private | You can move to private collection, or to a written agreement, at any point |
Don’t declare the pay rise and the assessment stays low | The debt is generated retrospectively once the tax return is lodged. It does not disappear |
That last one deserves emphasis, because it is advice given freely on the internet and it is wrong in a way that costs people money. Assessments run on last year’s taxable income, so the system lags reality by roughly a year. A promotion in March shows up in an assessment the following August. The lag is not a loophole. When the return is finally lodged, the assessment is amended back to the relevant period, and the arrears crystallise, often as a lump sum landing at the worst possible moment.
When can a 50/50 assessment be changed?
Through a change of assessment application to Services Australia, on one or more of the ten grounds in section 117(2) of the Child Support (Assessment) Act 1989. You need special circumstances, meaning something out of the ordinary, and the change has to be just and equitable.
The grounds that matter in shared care matters:
- Reason 3, high costs of educating the child in the manner both parents intended. This is the private school ground, and it turns on evidence that both parents intended it. Enrolment forms signed by both, or correspondence, or a parenting plan recording the decision.
- Reason 2: the special needs of the child, covering significant medical, disability or learning needs.
- Reason 8A and 8B, where the assessment is unfair because of a parent’s income, property and financial resources, or their earning capacity.
Reason 8 is the emotional centre of most disputes and the most misunderstood. Suspicion is not enough. A parent whose reported income sits well below their visible lifestyle may well be a legitimate Reason 8 case, and business structures, trust distributions and deliberately reduced hours all fall within it. But the application needs material: bank records, business financials, evidence of the working pattern before and after separation. A hunch that the other parent is doing better than the return suggests will not survive a case officer’s review.
If the decision goes against you, you can object and receive written reasons, then seek external review through the Administrative Review Tribunal, which replaced the AAT in October 2024.
Courts do have a role. Under section 116, a party can apply for a departure order under section 118, and section 112 leave allows an application reaching back beyond 18 months. In practice this is a smaller and harder road than the administrative one, and it is not where a straightforward shared care dispute should start.
Where to go from here
Run the estimator first. Bring the result, your last two tax returns and a clear picture of the care pattern to a first appointment, because that combination answers most of the question before anyone bills you for it. Where the numbers look wrong, the useful conversation is about which of the ten grounds fits your facts and what evidence you can actually produce.
This is general information about the child support scheme in NSW and not advice on your matter. If you want the assessment reviewed properly, or the extras documented so they hold, arrange a confidential consultation with our family law team.
Frequently asked questions
Your new partner's income is not counted in the assessment. A child of that relationship is a different matter: once you have at least 35% care of them, they may be recognised as a relevant dependent child, which reduces your child support income before the formula runs.
At 18. If the child turns 18 during their final year of secondary school, the receiving parent can apply to extend the assessment to the end of that school year, but the application must be made before the eighteenth birthday unless exceptional circumstances apply. Section 151B is unforgiving on timing, and the reminder letter from Services Australia is easy to miss in a busy household. Separately, a court can order adult child maintenance under section 66L where support is needed to complete education or because of a disability.
Two options exist. A limited child support agreement needs an assessment already in place, must be for at least the assessed amount, and either parent can end it after three years or if the notional assessment shifts by more than 15%. A binding child support agreement can be for any figure, including nil, and can deal with school fees directly. Both parents must get independent legal advice from separate lawyers, who each sign a certificate, and a binding agreement is difficult to unwind afterwards.
Services Australia can apply a provisional income, often based on the previous year indexed forward, and the assessment moves for reasons unconnected to either parent's real position. Ask for the assessment to be amended once the return is lodged.
Care arrangements and child support are separate questions with separate processes. Changing the pattern of nights is dealt with through a parenting plan or parenting orders, and any change to care is then reported to Services Australia, which adjusts the assessment from the date of the change or the date of notification.
