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Every calculation is unlocked. Change the nights of care, either income or a child's age and re-run it as many times as you like — nothing is deducted, nothing counts down, and none of it expires.
An assessment made this year runs for the next eighteen
You have a figure, a letter that does not explain it, and an arrangement to agree with somebody you are not getting on with. Nobody has mentioned that the rules turn nights of care into money in seven steps, that five of those steps are flat, or that there are ten separate reasons an assessment can be changed.
Services Australia's estimator is free and it is the official one — and it will not model a change of assessment, a second family, two cases at once, or what happens if care moves by a single night. This does all four, in about three minutes.
A rough guide on two children aged 6 and 11. The full calculator asks about your own children's ages, second families and everything else.
If this is you
The child support scheme is an eight step formula, a table in a schedule to an Act, a seven band conversion nobody prints, and ten separate grounds for departing from all of it. It was written for administrators and it is explained to parents in a letter.
The assessment notice gives you an amount and the figures behind it, and nothing that tells you which of eight steps produced it. So the only way to check whether it is right is to already know how it works.
Adjusted taxable income, child support income, income percentage, care percentage, cost percentage, child support percentage. Six terms, five of them meaning something different, and every one of them decides part of the amount.
A friend says it counts. A forum says it does not. It does not — not on either side, at any income. The confusion comes from Family Tax Benefit, where a partner's income does count, and the two are constantly mixed up.
The question everybody asks before signing a parenting plan, and the one nobody answers with a number. A single night a fortnight either side of a line in the table can be thousands of dollars a year, for as long as the assessment runs.
You type in the children, the nights and the two incomes. We run the same eight step formula Services Australia runs, show every line of it with your figures in it, and then price every lawful route your assessment could take. No appointment, no sales call, and nothing you enter leaves your browser.
Three questions, thirty seconds, and you will know roughly where you stand. It costs nothing.
The loss
Both have two children aged 6 and 11. Both earn the same. Both agreed an arrangement in good faith without checking a table neither had been shown. One of them landed on 51 nights a year and the other on 52.
Both parents are invented. Nothing else here is: the two incomes are annualised male total average weekly earnings and the default income the scheme itself uses, both published in the Child Support Guide, and the arithmetic is the eight step formula applied to them. Run the same figures yourself in about thirty seconds.
The alternatives
| Guess What most people do |
The official estimator Services Australia |
Child Support Calculator This calculator |
|
|---|---|---|---|
| What it costs | Nothing now, years of the wrong figure |
Free | $249 |
| The eight step formula | |||
| All ten change of assessment reasons priced | |||
| Multi-case, second families, carers | |||
| What one more night of care is worth | |||
| Every year until your youngest turns 18 | |||
| It is the actual assessment |
The clock
Child support runs on dates, and missing one makes the choice for you at a figure you did not pick and often cannot change back. None of these is an offer and none of them is ours.
Tell Services Australia within 28 days of a care arrangement changing and the new level generally applies from the day it changed. Later than that, an increase in your care usually applies only from the day you told them — while a decrease still applies from when it happened. Where the care steps are.
The self-support amount, the whole costs of the children table, the fixed rate and the minimum rate are all indexed on 1 January. A calculation against last year's figures is not slightly out, it is out in every line. These are the — figures, and the self-support amount is —.
Current income has to be at least — below the income in your assessment before an estimate can be lodged. At 14% below you cannot lodge one, and an estimate never backdates — every week of delay is a week assessed on the old figure.
The report
The free estimate tells you what your assessment is and roughly how much is riding on it. This is the part that shows the working and prices every route. Eleven sections and thirteen charts, on your own figures, with every line of arithmetic visible so you can check it or argue with it.
See a real one, free — an invented household run all the way through, with the open half exactly as a customer sees it, and the assistant live on it for two questions.
How it works
If you can read a payslip, you can use this. Simple mode asks six questions. Advanced adds second families, second cases and the change of assessment amounts.
How many children and how old, how many nights a year they are with you, and both adjusted taxable incomes. That is it. We never ask for a name, a Customer Reference Number, a tax file number or a bank detail, because none of them are part of the arithmetic.
Your assessment a year and a week, your care percentage and what it is credited as, where the next care step falls in both directions, and every lawful route open to you named and explained in full.
$249 opens the full report: the eight steps with your figures, all ten change of assessment reasons, every night of care, and every year until your youngest turns 18. PDF included, ready to take to a mediation.
The eight steps are section 35. The costs table is Schedule 1. The care conversion is section 55C. The ten reasons are section 117(2). Every figure comes from the Child Support Guide, section 2.3.2.
The report writes out all eight steps with your own numbers in each line and the section of the Act beside it, so you can check the line you disagree with rather than the whole answer.
We are not licensed to tell you what to do, and Services Australia is the only body that can tell you what your assessment actually is. The arithmetic is the part people are missing, not the opinion.
If the report does not apply to your circumstances, tell us what went wrong within 14 days and it is refunded in full.
Included with the report
Every report comes with an assistant that has read your report — your children, your nights, your two incomes, every route priced — and answers questions about it in plain English. Not a search box and not a help page.
An example of the kind of answer it gives, on the sample report's figures.
Pricing
One payment, no expiry, nothing to renew, and we never keep your card. It opens the whole report and lets you redo the sums as often as you like — which matters, because a child support assessment is remade every January and every time care or income moves.
Prices in Australian dollars. Paid securely through PayPal — card or PayPal balance, no account needed. See a sample report before you decide.
Questions
Through an eight step formula. Both parents' adjusted taxable incomes have a self-support amount of $31,046 taken off them, plus anything for other children they support. What is left is added together, and each parent's share of that combined figure is their income percentage. Nights of care become a care percentage, which a table turns into a cost percentage. Income percentage minus cost percentage is the answer.
No. Not on either side, at any income, and it never has. Only the two parents' own adjusted taxable incomes are used, and a non-parent carer's income is not counted either. A partner's income does affect Family Tax Benefit, which is a separate payment with separate rules, and that is where the confusion usually starts.
Either nothing at all or thousands a year, depending entirely on which side of a step you are standing. The care table has seven bands and five are flat, so between 52 and 127 nights an extra night is worth nought — and then one night crosses a line. The steps fall at 52, 128, 176, 190, 238 and 314 nights a year.
It is an application to have the formula set aside for your case because it produces an unfair result, and it costs nothing. There are ten reasons in section 117(2) and you have to make out at least one of them with evidence. Either parent can apply, Services Australia decides it rather than a court, and the other parent gets to respond.
If it has dropped by at least 15%, you can lodge an income estimate — but it takes effect from the day you lodge it and never before, so every week of delay is a week assessed on the old figure. A drop of less than 15% is not enough on its own and would need one of the ten change of assessment reasons instead.
No, and nothing here pretends to be. Services Australia administers the child support scheme and is the only body that can tell you what your assessment is. This applies the published rules to the figures you type in, shows every step, and prices the routes the official estimator will not model.
A parenting plan gets signed, a care percentage gets recorded, and both of them hold until somebody goes to the trouble of changing them. Almost nobody does. Three minutes now, on the actual arithmetic, is the cheapest three minutes in the whole process — and it is a great deal cheaper than finding out in four years.
No card. No sign up. Your answer on the next screen.
You do not need to understand the formula. You need to know what it produces, and what else it could.
Runs the full eight step formula including multi-case, second families and non-parent carers — then prices all ten change of assessment reasons and every one of the 365 nights of care, which the official estimator does none of.
Child support figures as at —.
Your estimate
The gap between the lawful routes open to you, on your own figures, over the years your assessment has left to run.
You can provide a different email to use as your login - or the PayPal one
And you can ask it questions. Your report comes with an assistant that has read it and explains any figure in plain English — if you want it. It is given the amounts on your report, never your name or your email, and the conversation stays in your browser.
A link straight back to this estimate, the 1 January 2026 figures it was built on, and the two deadlines that decide it for you — the 1 January indexation and the 28 day rule on reporting a change in care.
One email, then only if the figures change or a deadline is close. Unsubscribe in one click. We never sell your address.
One payment, and it never expires
A $50 a week error in a child support assessment is over $45,000 by the time the youngest child turns 18. This prices every lawful route your assessment could take, on your own figures, so the arrangement is agreed on arithmetic rather than on a guess.
Yes, it is included, and using it is entirely your choice. It sits behind one button on your report and does nothing until you press it — nothing in the report is held back from somebody who never opens it.
When you do ask it something, what it receives is the figures on your report: amounts and categories. Not your name, not your email address, not your account, and never a Medicare number, tax file number or bank detail — we do not hold those in the first place. The name you can put on the report cover is optional and is not part of what it is given. The conversation stays in your browser tab and is gone when you close it, and we record that a question was asked without recording what it said.
Section 5 of the privacy policy sets out exactly what does and does not travel, including who processes it.
No. You pay once and the access is yours. There is no subscription and nothing renews. PayPal handles the payment, so we never even see your card number.
No, and nothing here pretends to be. Services Australia administers the scheme and is the only body that can tell you what your assessment is. This applies the published rules to the figures you type in, shows all eight steps of the working, and prices the routes the official estimator will not model — a change of assessment, a second case, a second family, or what one more night of care is worth.
Child Support Calculator provides information, not financial product advice. We are not licensed to give personal financial advice and we never tell you which option to pick. What we do is apply the published rules to the figures you enter and show you what they produce, with every working visible. <then name who actually decides: your real position is set by [the authority] and by the agreement you sign with [the other party]>
Pay once and the full report opens straight away — and stays open, on this and every scenario you run afterwards.
You can provide a different email to use as your login - or the PayPal one
Worked examples
Every household on this page is invented. Nothing the calculator does with them is. The inputs are written down in one file, the same engine that builds a paid report solves them when this page loads, and whatever it produces is what the cards show — so when the figures are indexed next January, this page moves with them and nobody has to remember to update it.
The rules credit each parent with a share of the children's costs based on how much of the year the children are with them. That share moves in seven bands, and five of the seven are perfectly flat — so dozens of extra nights can be worth nothing at all, and then a single night is worth a whole step.
A fixed self-support amount comes off each parent's income first, whatever they earn. Two parents on $60,000 each have a combined child support income of about $58,000 rather than $120,000, and the children's costs are read off that smaller figure.
Section 117(2) sets out ten grounds for departing from the formula. Either parent can apply, there is no fee, and Services Australia decides it rather than a court. What stops most people is not the cost — it is that nothing in the ordinary process ever mentions the ten reasons exist.
Everything below is those three facts in real dollars, for thirteen different households. Worked out on the current child support figures.
Your own figure turns on five things: how many children, how old they are, how many nights a year they are with you, and both adjusted taxable incomes. Change any one of them and the routes above change size and change order. It takes about three minutes and costs nothing.
Prepared for your household
Every lawful way this assessment could be a different number, and what each one leaves you with over the 11 years it has left to run. Same 2 children, same two incomes, same published figures — the difference is only in which part of the formula moves. Open Show Details on any of them for what it means and what the process actually involves.
What the big number is. The total child support assessed between now and the day your youngest turns 18, with the children ageing through the costs table as the years pass and dropping off the assessment as they turn 18. Child support you pay counts as money out and child support you receive counts as money in, so the same ranking works from both sides. It is the only figure worth comparing routes on, because an assessment is a weekly number and a childhood is 11 more years of them.
Doing nothing has a price, and it is on the list. On these figures the gap between the route that leaves you with the most and the one that leaves you with the least is $91,744 — on the same children, the same incomes and the same rules. Leaving the assessment as it is is a row on that list like any other, and it has a figure beside it.
Every route here is lawful and open to you. All of them are in the Child Support (Assessment) Act 1989, all of them are free to apply under, and Services Australia decides them rather than a court. They differ in what they leave behind, not in whether you are allowed to take them. Nothing in this report is a recommendation: these are your own figures run through the published rules, and which route is taken is your decision to make.
Four numbers. Everything after this explains where they came from.
That is not a projection about the future and it is not an estimate of your chances. It is the distance between the 9 lawful routes priced in section 01 above, over the 11 years this assessment has left to run — $8,340 a year, $160 a week. Every one of those routes is lawful, free to apply under, and decided by Services Australia rather than a court. 6 of the 9 are priced on an illustrative amount rather than one you entered, and each of them says so on its own row; the free page you saw before paying quoted the narrower distance across the 3 that were not, which is why the figure here is the larger of the two. What decides which of them is actually open to you is evidence, and sections 06 and 07 set out exactly what each one needs.
This is the formula in section 35 of the Child Support (Assessment) Act 1989, run exactly as Services Australia runs it. Every line carries its section so you can check the one you disagree with rather than argue with the whole answer.
| Step | What happens | You | The other parent |
|---|---|---|---|
| — | Adjusted taxable income s 43 | $104,000 | $58,000 |
| 1 | Less the self-support amount s 45 | −$31,046 | −$31,046 |
| 1 | Child support income s 41 | $72,954 | $26,954 |
| 2 | Combined child support income s 42 | $99,908 | $99,908 |
| 3 | Income percentage s 55B | 73.02% | 26.98% |
| 4 | Percentage of care s 48 | 26% (96 nights) | 74% (269 nights) |
| 5 | Cost percentage s 55C | 24% | 76% |
| 6 | Child support percentage s 55D | 49.02% | −49.02% |
| 7 | Costs of the children s 55G, Sch 1 | $23,242 | $23,242 |
| 7 | Cost of each child s 55H | $11,621 | $11,621 |
| 8 | Annual rate of child support s 35, 67A | $11,394 | — |
Step 6 is the whole answer. Your income percentage minus your cost percentage is 49.02%. A positive number means that parent is not meeting their share of the children's costs through care, so they pay the difference; a negative one means they are meeting more than their share, so they receive it. With two parents and nobody else the two percentages are exact opposites, which is why only one parent can ever be the paying one.
Nothing a new partner earns appears anywhere above. It is not part of a child support assessment on either side, at any income. It can affect Family Tax Benefit, which is a different payment with different rules, and that is usually where the confusion starts.
Ranked on one measure and one only: what the assessment leaves you with over the 11 years it has left. Child support paid counts as money out and child support received counts as money in, so the top row is the one that leaves you with the most. Nothing here is a recommendation.
| # | Route | This year | A week | Over 11 years | Against leaving it |
|---|---|---|---|---|---|
| 1 | Change of assessment on the costs of the children modelled on $5,200 of recognised costs a year | $8,743 out | $168 | $98,683 | −$29,156 |
| 2 | Lodge an income estimate for this financial year modelled on $88,400 a year, the highest an estimate could be | $8,743 out | $168 | $98,958 | −$28,881 |
| 3 | Record one relevant dependent child living with you modelled on one dependent child, in your care full time | $9,400 out | $181 | $106,400 | −$21,439 |
| 4 | Change of assessment on income, earning capacity or resources the assessment cannot see modelled on $10,000 a year attributed to the other parent | $10,697 out | $206 | $118,672 | −$9,167 |
| 5 | Change of assessment on the child's own resources, or what has already changed hands modelled on $1,000 of resources a year | $10,903 out | $210 | $122,443 | −$5,396 |
| 6 | Care recorded at 128 nights a year — the next step up modelled on 128 nights a year | $11,161 out | $215 | $125,231 | −$2,608 |
| 7 | Change of assessment on your capacity to support the child modelled on $1,000 a year recognised | $11,233 out | $216 | $126,193 | −$1,646 |
| 8 | Leave the assessment exactly as it is | $11,394 out | $219 | $127,839 | — |
| 9 | Care recorded at 51 nights a year — the next step down modelled on 51 nights a year | $16,972 out | $326 | $190,427 | +$62,588 |
Change of assessment on the costs of the children. Reasons 1, 2, 3 and 6 — the cost of getting to the children, special needs, an education both parents intended, and child care for a child under 12. All four work the same way: the costs of the children go up, and the parent meeting them is credited. Priced on $5,200 of recognised costs a year. Section 117(2), reasons 1, 2, 3 and 6
Lodge an income estimate for this financial year. An estimate can only be lodged when current income is at least 15% below the income in the assessment — here, $88,400 or less. Priced on $88,400 a year, the highest an estimate could be. Sections 60 to 64A
Record one relevant dependent child living with you. A child of yours in your care at least 128 nights a year who is not in any child support assessment. The amount comes off your income before anything is shared out. Priced on one dependent child, in your care full time. Section 46
Change of assessment on income, earning capacity or resources the assessment cannot see. Reason 8, and the one most applications are made under. It reaches money that never becomes adjusted taxable income, and a parent who could earn considerably more than they do. Priced on $10,000 a year attributed to the other parent. Section 117(2), reason 8
Change of assessment on the child's own resources, or what has already changed hands. Reasons 4 and 5 — the child has income or property of their own, or money, goods or property have already been transferred for the child's benefit. Both reduce what is left to share. Priced on $1,000 of resources a year. Section 117(2), reasons 4 and 5
Care recorded at 128 nights a year — the next step up. The next night at which the cost percentage changes at all. Every night between 96 and 127 is worth exactly nothing, and then this one is worth a step. Priced on 128 nights a year. Sections 48 and 55C, and the care and cost table
Change of assessment on your capacity to support the child. Reasons 7, 9 and 10 — necessary expenses that are genuinely out of the ordinary, a duty to maintain another child or person, and responsibility for a resident child. All three work by adjusting the income the formula runs on. Priced on $1,000 a year recognised. Section 117(2), reasons 7, 9 and 10
Leave the assessment exactly as it is. The eight step formula on the figures already recorded. Every other row on this list is this row with one thing changed. Sections 35 to 66 of the Child Support (Assessment) Act 1989
Care recorded at 51 nights a year — the next step down. The nearest night below where the cost percentage changes. Care is disputed in both directions, and the step is the same size going down as coming up. Priced on 51 nights a year. Sections 48 and 55C, and the care and cost table
Your 96 nights a year are 26% of the care, which section 55C credits as 24% of the children's costs. The next step up is at 128 nights and the next one down is at 51. Every night in between is worth exactly the same amount.
The next 32 nights of care are worth nothing at all, and then one night is worth $233 a year. At 96 nights you are credited with 24% of the children's costs. At 128 nights that becomes 25%. Nothing between the two changes anything. Over the 11 years this assessment has left, that single night is $2,563.
It goes the other way too. If the care recorded fell to 51 nights a year the assessment would move by $5,578 a year. Care is disputed in both directions, and a parent who loses a step loses the whole of it at once rather than a night at a time.
Telling Services Australia within 28 days matters more than it looks. A care change reported inside that window generally applies from the day it happened. Reported later, an increase in care usually applies only from the day they were told, while a decrease still applies from when it happened — so late notice costs the parent whose care went up and costs nothing to the one whose care went down.
Section 117(2) sets out ten reasons an assessment can be departed from, and applying costs nothing. Each one is priced below on your own figures, and each carries the amount it was modelled on and what every further $1,000 recognised under it would do — so a reader whose circumstances are nothing like the model can scale it themselves.
| # | Reason | Modelled on | A year | Per $1,000 | Over 11 years |
|---|---|---|---|---|---|
| 1 | The cost of spending time with the child must exceed 5% of your income — $5,200 | $5,200 modelled | −$2,651 | −$510 | −$29,156 |
| 2 | The child's special needs | $1,000 modelled | −$510 | −$510 | −$5,605 |
| 3 | Education both parents intended | $1,000 modelled | −$510 | −$510 | −$5,605 |
| 4 | The child's own income or property | $1,000 modelled | −$491 | −$491 | −$5,396 |
| 5 | Money or property already transferred | $1,000 modelled | −$491 | −$491 | −$5,396 |
| 6 | Child care costs, child under 12 must exceed 5% of your income — $5,200 | $5,200 modelled | −$2,651 | −$510 | −$29,156 |
| 7 | Necessary expenses reduce capacity | $1,000 modelled | −$161 | −$161 | −$1,646 |
| 8 | Income, capacity or resources not in the assessment | $10,000 modelled | −$697 | −$72 | −$9,167 |
| 9 | Supporting another child or person | $1,000 modelled | −$161 | −$161 | −$1,646 |
| 10 | Supporting a resident child | $1,000 modelled | −$161 | −$161 | −$1,646 |
Reasons that move the same part of the formula share the figure you entered for them, so some rows above are identical. Reasons 1, 2, 3 and 6 all raise the costs of the children and all read the same box; reasons 4 and 5 both reduce them; reasons 7, 9 and 10 all adjust your own income. That is the arithmetic being honest rather than a duplication — two reasons that work the same way on the same amount are worth the same, and which of them you can actually make out is a question about evidence rather than about money.
Which direction a reason moves the assessment depends on which side of it you are on. On your figures every one of the ten would lower what you pay, and none of them would raise it. The other parent can apply under any of them too, and often does in response.
The largest single effect here is reason 1 — The cost of spending time with the child. On the amount it is modelled on it moves the assessment by $2,651 a year, and $29,156 over the 11 years remaining. That is not a prediction that an application would succeed — it is what the arithmetic does if one did.
The per $1,000 column is the one to use if none of the modelled amounts fit you. It is a rate of change rather than a claim: multiply it by whatever your own figure is and the answer is the same arithmetic this report ran.
A change of assessment is decided on evidence rather than on how strongly either parent feels about the figure. Being unhappy with the amount is not one of the ten reasons, and three kinds of material are refused outright however relevant they seem.
Reason 1 — The cost of spending time with the child. Getting to the children costs a lot — flights, fuel, somewhere to stay, phone calls. The costs have to be more than 5% of the adjusted taxable income used in the assessment. Where a parent already has the children at least 52 nights a year, travel is the only cost that counts here, because the rest is already in the formula. Evidence: Airline bookings, fuel and accommodation receipts, a parenting plan or court order, or an estimate of what the coming year will cost. Not counted: Food, clothes and entertainment are never counted under this reason.
Reason 2 — The child's special needs. A physical, mental or learning disability, and also a special talent or ability. Therapy, equipment, a private tutor for a significant learning disability, tuition for a gifted musician. What is counted is what is left after any rebate or refund. Evidence: Medical evidence of the condition and its treatment, receipts for support services, and an estimate of future costs. Not counted: Anything reimbursed, and ordinary daily costs like food, clothing and standard medical care.
Reason 3 — Education both parents intended. Usually a private school. The point of this reason is not that the school is expensive — it is that both parents meant the child to go there, and one of them is now carrying the fees alone. Evidence: Enrolment forms signed by both parents, a parenting plan or court order, and receipts for the fees. Not counted: A school one parent chose on their own is much harder to run under this reason.
Reason 4 — The child's own income or property. The child has enough money of their own to need less from their parents — a job, an inheritance, a trust. It has to be real money, not pocket money. Evidence: Payslips, bank statements or trust records for the child. Not counted: Any Centrelink income support payment the child receives is left out of this.
Reason 5 — Money or property already transferred. Something has already changed hands for the child — often as part of a property settlement, sometimes a car, a house, or school fees paid years in advance. The assessment does not know about it unless somebody says so. Evidence: Court orders, settlement agreements, and bank statements showing the transfer. Not counted: Ordinary gifts and ordinary spending on the children are not transfers.
Reason 6 — Child care costs, child under 12. Day care, before and after school care, vacation care — for a child under 12. For a parent the costs have to be more than 5% of their adjusted taxable income. For a non-parent carer they have to be at least 25% of the costs of the child. Evidence: Child care receipts, enrolment forms, and statements of the subsidy already received. Not counted: Only the amount left after the Child Care Subsidy and any other assistance counts.
Reason 7 — Necessary expenses reduce capacity. High costs that are both necessary and out of the ordinary — major medical treatment, or the cost of setting up a home again after separating. An ordinary mortgage is not this. Evidence: Payslips, medical accounts, and receipts for the expense itself. Not counted: Normal living costs, and debts taken on by choice.
Reason 8 — Income, capacity or resources not in the assessment. The reason most applications are made under. It covers two different things: money and resources that never reach adjusted taxable income at all, and a parent who could earn far more than they do. Services Australia can start a change under this reason without anybody applying. Evidence: Payslips, business profit and loss statements and balance sheets, and anything showing a parent is choosing to earn less than they could. Not counted: An income drop of 15% or more is an income estimate, not a change of assessment. A drop of less than 15% is not enough on its own.
Reason 9 — Supporting another child or person. Another child, a former partner receiving maintenance, or a partner who cannot support themselves. A child already counted in the assessment as a relevant dependent child cannot be counted again here unless they have special needs. Evidence: Court orders, proof of payments, and evidence of why the person cannot support themselves. Not counted: Stepchildren are dealt with under reason 10, not this one.
Reason 10 — Supporting a resident child. A child who lives with the applicant, is not legally theirs, is under 18, is not in a couple, and needs financial help — usually a stepchild. The applicant has to have been the partner of one of the legal parents for two years in a row, or the legal parents have to be unable to support the child. Evidence: Evidence that the legal parents cannot support the child, and evidence of the child's need. Not counted: A child who could be supported by their own parents is not a resident child for this.
Three kinds of material are refused outright. Anything offensive, abusive or derogatory; any statement from a child, including voice recordings, text messages and social media posts; and anything obtained illegally. An application carrying any of them is not weakened, it is refused.
Everything sent is copied to the other parent except Part A of the form. Part B and every attachment go across in full. Personal details are removed from attachments before they are sent — a phone number, an address, an email, a workplace, the children's school or day care, a vehicle registration. Where there is a risk to anybody's safety, Services Australia is told before anything is lodged.
Everything above is real arithmetic on a fictional household — the paid report's own sections, unaltered. Run yours and this half opens on your own figures: your children, your nights of care, your two incomes.
And you can ask it questions. Every report comes with an assistant that has read your report and explains any figure in it in plain English — why a route ranks where it does, what a term means, what changes if one more night of care is agreed. Using it is entirely your choice, it does nothing until you press the button, and it is given the amounts on your report and never your name, your email or your account.
That is somebody else's answer. Yours takes about three minutes and costs nothing.
The link may have already been used. If you are still getting emails, write to us and we will stop them by hand.
Guides
Written for parents rather than for decision makers: plain English, the 1 January 2026 figures, and every step of arithmetic shown. Each of these answers one question properly rather than summarising the whole scheme badly.
Reading is useful. Knowing what your own assessment comes to, and what else it could be, is better.
Change of assessment
Reason 3 covers costs that are significantly affected because a child is being cared for, educated or trained in the way both parents intended. In practice that nearly always means private school fees. The critical word is "both" — this ground is not about the school being expensive, it is about the two parents having agreed the child would go there.
The words are that the costs of raising the child are significantly affected because the child is being cared for, educated or trained in the manner both parents intended.
Read that carefully, because two things follow that people often get wrong. First, it is not enough that a school is expensive — expense on its own is nobody's ground. Second, it is not enough that one parent has decided the child should go there. The intention has to have been shared.
It also covers more than schools. Training, and other forms of education both parents intended, fall within it — though schooling is what it is used for in almost every case.
This is where these applications are won and lost. The strongest evidence, by a distance, is an enrolment form or application signed by both parents. It is contemporaneous, it is unambiguous, and it is very hard to argue with.
Beyond that, the kinds of evidence that carry weight:
The last one matters more than people expect. A parent who has attended parent-teacher interviews for four years is in a weaker position to say the enrolment was never agreed.
This is much harder, and it is honest to say so. A parent who enrols a child in a private school after separation, without the other parent's agreement, and then applies to have the fees recognised is asking the Registrar to make the other parent pay for a decision they were not part of.
It is not impossible — the Registrar still has to consider what is just and equitable, and there are circumstances where a unilateral decision was clearly in the child's interests and the other parent was unreachable. But the ground is built around shared intention and an application without it is starting a long way back.
Fees, and receipts for fees. Where the school bills separately for compulsory items — levies, required technology, uniforms as a condition of enrolment — those can form part of it. Only the net amount after any scholarship, bursary or discount counts.
Discretionary extras are on much weaker ground: optional overseas trips, elective activities, things a family chooses on top of the enrolment.
Unlike reason 1 (travel) and reason 6 (child care), reason 3 carries no fixed percentage floor. The costs simply have to significantly affect the costs of raising the child.
In practice that is a lower bar for a modest income and a higher one for a large income, because "significant" is judged against the household rather than against an absolute figure. Private school fees are usually significant on any income, which is why this ground turns on intention rather than on amount.
Reason 3 raises the costs of the children by the amount recognised, and the parent actually paying the fees is credited with the whole of it. The net effect on the paying parent's assessment is a reduction of roughly the fees multiplied by the other parent's share of the costs.
On school fees of $18,000 a year, in a household where the other parent carries around a quarter of the costs, that is somewhere near $4,500 a year off the assessment — every year the child is at the school. It is one of the largest single effects available under any of the ten grounds, which is a reflection of how large school fees are relative to what the costs of the children table says children cost at all.
It works from the other side too. A receiving parent who is carrying school fees alone has exactly the same ground, and the change would run in their favour.
Three responses come up repeatedly, and it is worth thinking about them before lodging rather than after:
Part B of the form and every attachment are copied to the other parent. A school enrolment form typically carries the child's school, an address and often a phone number — take out anything you do not want shared before it goes in, because it will be shared.
The evidence guide covers the rest, including the three kinds of material that are refused outright.
The report works out what your own fee figure would do to the assessment, and gives the rate per $1,000 so you can scale it as the fees rise.
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About
Almost everybody meets the child support scheme at the worst possible moment. A relationship has ended, a care arrangement is being argued about, and a letter arrives with a figure on it and no working. That figure will run for years — often for more than a decade — and it is being set at the point when neither parent has the time, the money or the calm to go and check it. A difference of fifty dollars a week, which nobody thinks worth the argument in a fortnight, is over forty-five thousand dollars by the time the youngest child turns eighteen.
None of the rules are secret. The eight step formula is section 35 of the Child Support (Assessment) Act 1989. What the rules say children cost is a table in Schedule 1 of the same Act. The conversion from nights of care to a share of those costs is section 55C. The ten reasons an assessment can be departed from are section 117(2). The six figures that move every 1 January are published in the Child Support Guide at section 2.3.2, and the costs of the children table is on Services Australia's own website. Every one of them is free to read. What almost nobody ever sees is those rules applied to their own numbers, because they are spread across an Act, a schedule, a guide written for decision makers, and an annual indexation cycle nobody outside the field follows.
Child Support Calculator does one thing: it applies those published rules to your figures and shows you, in full, what they produce. All eight steps written out with your own numbers in every line and the section of the Act beside each one. Every lawful route your assessment could take, priced on a single stated measure. All ten change of assessment reasons, separately. The assessment at every one of the 365 nights of care, so you can see exactly where the steps fall before you agree to an arrangement rather than four years after. And every year until your youngest turns 18, with the children ageing through the costs table as they go.
We do not tell you what to do, and we are not licensed to. Services Australia administers the child support scheme and is the only body that can tell you what your assessment actually is — if the figures on your assessment notice differ from what you type in here, the notice is what governs. Nothing on this site is legal or financial advice, no route on it is recommended over any other, and whether an application is worth making turns on evidence, on what it does to Family Tax Benefit, and on whether it is worth the conflict — none of which is arithmetic. The arithmetic is the part people are missing. If you want the opinion as well, here is who does what, and the support page lists the free helplines.
One more thing, because it is asked often. We never ask for a name, a Customer Reference Number, a tax file number, a bank detail or anything that identifies a child. None of them are part of the arithmetic, so none of them are collected. The name you can put on the report cover is optional, is printed there and nowhere else, and is never part of what the assistant is given.
Short version: we hold as little as we can, we never ask for the identifiers that matter most, and the calculation runs on your own device. The long version is below, because you are entitled to it.
This policy explains how XTO Pty. Ltd. (we, us, our) collects, holds, uses and discloses personal information, and how you can access, correct or complain about it. We handle personal information in accordance with the Privacy Act 1988 (Cth) and the Australian Privacy Principles (APPs).
It applies to calculatedchoices.com.au and to every email we send you. It does not apply to any third party site we link to.
We do not ask for, and you should never send us, your Medicare number, tax file number, tax file numbers, Customer Reference Numbers, bank account numbers, or any government identifier, bank account details or card number. The calculator does not need them. If you send one to us anyway we will delete it rather than store it.
We do not collect sensitive information as defined in the Privacy Act — health information, racial or ethnic origin, political or religious beliefs, sexual orientation, or criminal record. Where the calculator asks about care needs it asks about funding categories, never about a medical condition.
Information you give us
Information collected automatically
In your browser, on your device. The figures you type into the calculator are processed locally to produce your result. They are transmitted to us only if you choose to save a scenario to your account. If you never save one, we never receive them.
Two exceptions, and both are things you have to choose to do:
A paid report comes with an optional assistant you can ask questions about your own figures. It is the one part of this site that sends anything to a third party, so it is set out here in full.
It is entirely your choice, and it does nothing until you use it. Nothing is sent anywhere unless you open the assistant and ask a question. If you never open it, this section does not apply to you at all, and the rest of the report works exactly the same.
What is sent when you do ask
What is not sent
What travels is a set of amounts and categories. On its own it does not identify anybody, and we do not send anything alongside it that would.
Who processes it
The request is answered by Google's Gemini API, which processes it outside Australia — see sections 10 and 11. We do not train any model on your figures and we have no arrangement permitting anyone to do so; what Google does with data sent to its API is governed by its own terms, which we do not control.
How long it is kept
Because the assistant is optional, you can have the entire paid report without any of the above ever happening. Nothing in the report is withheld from somebody who never opens it.
We use the following, and nothing else:
You can clear or block these through your browser at any time. Clearing them will sign you out and reset your preferences; the site will otherwise work normally.
We use Google Analytics and Google Ads to measure how people find and use the site and whether our advertising is worth running. Where these are enabled, Google receives your IP address, device and browser information, the pages you viewed, and — when you complete a purchase — the order reference and the amount paid. Google may set its own cookies and may combine this with data it holds from other sources. Google's handling of that data is governed by its own privacy policy, not ours.
We do not sell your personal information, and we do not disclose it to data brokers, advertising networks other than as described above, a Customer Reference Number or any other government identifier, or anyone who might try to sell you something.
You can opt out of Google Analytics using Google's browser add-on, and you can adjust personalised advertising in your Google account settings.
Payments are processed by PayPal. Your card or account details are entered on PayPal's systems and are never transmitted to, seen by, or stored on our servers. We receive only the transaction reference, the amount, the status and the email address associated with the payment.
Some of these providers store or process data outside Australia, principally in the United States (Google, PayPal) and, depending on our email provider, in other countries. By using the site you acknowledge that we take reasonable steps to ensure overseas recipients handle your information consistently with the APPs, but that we cannot control and are not accountable for how an overseas recipient handles it once disclosed, and that you may not be able to seek redress in that jurisdiction.
The site runs entirely over HTTPS. Passwords are stored as salted PBKDF2 hashes, not as text anyone here can read. Access to the database is restricted to those who need it. No system is perfectly secure, and we cannot guarantee the security of information transmitted over the internet, but we take reasonable steps to protect it from misuse, interference, loss and unauthorised access, modification or disclosure.
If a data breach occurs that is likely to result in serious harm, we will notify you and the Office of the Australian Information Commissioner as required by the Notifiable Data Breaches scheme.
If you give us your email address for a free estimate we may follow up about the full report. Every commercial email we send identifies us and carries a functional unsubscribe link, as required by the Spam Act 2003 (Cth). We action unsubscribes immediately. You will still receive transactional email — receipts, access details and password resets — because those are not marketing.
Write to support@calculatedchoices.com.au. We will:
We will respond within 30 days and will not charge you for making a request. We may need to verify your identity first.
If you think we have breached the APPs, write to support@calculatedchoices.com.au with "Privacy complaint" in the subject line. We will acknowledge within 5 business days and respond substantively within 30 days.
If you are not satisfied with our response, you may complain to the Office of the Australian Information Commissioner: oaic.gov.au, 1300 363 992, or GPO Box 5288, Sydney NSW 2001.
The site is intended for any parent or carer with a child support assessment, or about to have one. It is not directed at children and we do not knowingly collect personal information from anyone under 18.
We may update this policy. The effective date at the top changes when we do. Where a change is material we will tell you by email or by notice on the site before it takes effect. Continuing to use the site after that means you accept the updated policy.
Privacy Officer
XTO Pty. Ltd. (ACN [ACN NOT SET])
support@calculatedchoices.com.au
Plain English, because the whole point is that you understand it. Section 6 is the one that matters most — please read it before you rely on anything here.
By using calculatedchoices.com.au (the site) or buying a pass you agree to these terms. If you do not agree, do not use the site. In these terms we, us and our mean XTO Pty. Ltd.; you means the person using the site or, where you use it on behalf of another person or an entity, both you and that person or entity.
You must be at least 18 and legally able to enter a contract. The site is intended for use in Australia and applies Australian law and the Child Support (Assessment) Act 1989 and the child support figures published each January only. If you use it from outside Australia you do so on your own initiative and are responsible for local compliance.
Child Support Calculator is an information and calculation service. It applies the Child Support (Assessment) Act 1989 and the child support figures published each January to figures you supply and reports what those rules produce, showing its workings and naming the fee schedule used.
It is not financial product advice, personal advice, legal advice, tax advice, accounting advice or legal or financial advice, and it is not a recommendation to acquire, dispose of or deal in any financial product.
You should obtain independent, licensed advice before acting. Any decision you make is yours.
We take considerable care to keep the rates current and the formulas right, and every report prints the schedule it was built on. Even so:
Always confirm before you act.
You acknowledge and agree that you are solely responsible for evaluating the output, for verifying it against official sources, for obtaining independent professional advice, and for every decision you make or do not make. We are not your adviser and no fiduciary or advisory relationship arises from your use of the site.
You are responsible for keeping your password confidential and for everything done under your account. Tell us immediately at support@calculatedchoices.com.au if you suspect unauthorised use. We may suspend or close an account we reasonably believe is being used in breach of these terms.
A report you export as a PDF or otherwise save remains yours to keep and to show to family, an adviser or Services Australia. That licence is personal and non‑commercial. It does not permit republication, resale, or use as part of a product or service you provide to others.
Our promise: if the calculator cannot properly model your circumstances, or something has gone wrong, write to us within 14 days of purchase and we will refund the pass. No form and no argument. We would rather refund you than have you rely on a number that does not fit.
This is a voluntary commercial guarantee offered in addition to, and it does not limit, your rights under the Australian Consumer Law. Refunds are made to the original payment method within five business days of us accepting the request.
You must not:
All content, code, calculation methodology, report design, text and branding on the site is owned by us or licensed to us and is protected by copyright and other laws. Legislated rates and government data are not owned by anyone; our expression, arrangement and implementation of them is. Nothing in these terms transfers ownership to you.
We aim to keep the site available but do not guarantee it will be uninterrupted, timely, secure or error free. We may modify, suspend or discontinue any part of it, and may perform maintenance, at any time. If we permanently discontinue the service while your pass is running, we will refund the unused portion.
The site relies on third party services including PayPal, Google and our hosting and email providers, and links to third party sites and government resources. We are not responsible for those services or sites, their availability, their content or their terms.
Our goods and services come with guarantees that cannot be excluded under the Australian Consumer Law. For major failures with the service, you are entitled to cancel your service contract with us and to a refund for the unused portion, or to compensation for its reduced value. You are also entitled to be compensated for any other reasonably foreseeable loss or damage. If the failure does not amount to a major failure, you are entitled to have problems with the service rectified in a reasonable time and, if this is not done, to cancel your contract and obtain a refund for the unused portion of the contract.
Nothing in these terms excludes, restricts or modifies any consumer guarantee, right or remedy conferred by the Australian Consumer Law or any other law which cannot lawfully be excluded, restricted or modified. If any part of these terms would do so, that part does not apply.
Subject always to section 15, and to the maximum extent permitted by law:
You agree that this allocation of risk is reasonable given the price of the service and that the service is information rather than advice.
Our liability is reduced to the extent your loss is caused or contributed to by you, including by entering incorrect figures, by failing to verify output against official sources, or by failing to obtain independent advice.
To the maximum extent permitted by law, you indemnify us against any claim, loss, liability, cost or expense (including reasonable legal costs) arising from your breach of these terms, your misuse of the site, or your provision of the site's output to a third party who relies on it. This does not apply to the extent the claim arises from our own breach, negligence or wilful misconduct.
You may stop using the site at any time. We may suspend or terminate your access immediately if you breach these terms. Sections 4, 5, 6, 9, 12, 15, 16, 17, 19 and 20 survive termination.
Our Privacy Policy forms part of these terms and explains how we handle personal information.
These terms are governed by the laws of New South Wales, Australia. You and we submit to the non‑exclusive jurisdiction of the courts of New South Wales and the courts entitled to hear appeals from them.
XTO Pty. Ltd. (ACN [ACN NOT SET])
support@calculatedchoices.com.au