How is Child Support Calculated? A Guide for Australian Parents

Separation brings enough stress without wrestling with confusing child support formulas. You’re likely wondering how much you’ll pay or receive, and whether the system is fair.

Here’s the straightforward answer: Services Australia uses an 8-step formula that considers both parents’ incomes, the amount of time you spend with your children, and your children’s ages. Most parents will see assessments ranging from a minimum $534 per year to amounts based on their combined income and care arrangements.

Quick Answers

• Child support is calculated using both parents’ taxable income minus a self-support amount, multiplied by official cost tables
• The parent with higher income and less care time typically pays the parent with more care time
• Care percentage matters – having your child 5 or more nights per fortnight (35%+ care) can significantly affect the calculation
• You can apply through Services Australia, create a private agreement, or work with family lawyers in Townsville for binding arrangements

What Is Child Support?

Child support ensures both parents contribute financially to raising their children after separation. It’s governed by the Child Support (Assessment) Act 1989 and administered federally by Services Australia, so the same rules apply whether you’re in Townsville, Sydney, or Perth.

How the Calculation Actually Works

Services Australia uses an 8-step formula. Don’t worry – you won’t need to calculate this yourself, but understanding the steps helps you know what affects your payment.

Step 1: Work out each parent’s child support income

Start with your taxable income and subtract the self-support amount. For 2025, this self-support amount is approximately $29,841 (one-third of Male Total Average Weekly Earnings). This recognises you need income to support yourself before contributing to child support.

Step 2: Calculate combined child support income

Add both parents’ child support incomes together.

Step 3: Determine each parent’s income percentage

Divide your child support income by the total combined income. If you earn 70% of the combined income, your income percentage is 70%.

Step 4: Calculate care percentage

Based on how many nights per year your child stays with you. Having your child 128 nights per year equals 35% care – a critical threshold.

Step 5: Work out cost percentage

Services Australia converts your care time into a cost percentage, recognising that caring for children directly reduces your need to pay support.

Step 6: Calculate child support percentage

Subtract your cost percentage from your income percentage. If the result is positive, you pay support. If negative, you receive it.

Step 7: Determine the costs of the child

Services Australia publishes annual Costs of Children Tables based on your combined income and the child’s age. Children under 13 have lower assessed costs than teenagers aged 13+.

Step 8: Calculate the final amount

Multiply your child support percentage by the child’s assessed costs. This gives your annual payment amount.

What About Equal Shared Care?

If you and your former partner share care 50/50 but have different incomes, child support may still apply. The higher earner typically pays the difference to balance each parent’s financial contribution. This recognises that the child should benefit from both parents’ earning capacity.

Minimum and Fixed Rates

Not everyone follows the standard formula:

• Minimum rate: $534 per year (2025) applies when the formula calculates less than this amount
• Fixed rate: $1,768 per child per year (2025) applies to low-income payers with less than 35% care, capped at three children

How to Get Started

You have three options:

1. Apply through Services Australia for an official assessment and managed collection. This provides enforcement options if payments aren’t made.
2. Create a private agreement where you both agree on an amount. Limited agreements must equal at least the assessed amount. Binding agreements can be any amount but require independent legal advice for both parties.
3. Self-manage by reaching your own informal arrangement, though this offers no legal recourse if payments stop.

Most separated parents use Services Australia’s assessment to ensure fairness and accountability.

What If the Assessment Seems Unfair?

You can challenge an assessment if special circumstances exist, such as high costs for a child with special needs, private school fees both parents agreed to, or significant changes in income.

Apply for a change of assessment within 18 months through Services Australia. After 18 months (up to seven years), you’ll need to apply through the Federal Circuit and Family Court of Australia.

You must report changes immediately – new income, altered care arrangements, or relationship status changes can all affect your assessment. Some changes can’t be backdated, so prompt reporting protects you financially.

Get Expert Support

Child support calculations might seem complex, but they’re designed to ensure your children receive fair financial support from both parents. 

If you’re unsure about your assessment or need help establishing a fair arrangement, professional legal advice ensures you’re neither paying too much nor receiving too little – and most importantly, that your children’s needs are properly met.

Navigating child support alongside child custody lawyers and property settlement can feel overwhelming. At Townsville Family Lawyers, our experienced team helps parents understand their obligations and rights under the Child Support Scheme.

We’ll review your assessment, explain whether it’s fair given your circumstances, and help you negotiate binding agreements that protect your children’s interests and your financial stability.