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Use our calculator to estimate how much you might get or pay with our child support formula.

If the child lives with each parent some of the time, our calculator will also suggest who may pay and who may receive child support.

The calculator is only as accurate as the information you give. It does not send any information to us.

Before you start

You’ll need details of:

  • your income – this is your taxable income from the last calendar year (if you get salary, wages, a benefit or other income taxed at source) or your net income from 2 years ago (if you file an IR3 return)
  • your children – those you want child support for, and any of your other dependent children living with you
  • the other parent’s income – use your best guess if you do not know this
  • the other parent’s other children – any they already pay child support for, and any of their other dependent children living with them (for example, with a new partner).

Tell us about yourself

The calculator is in step 5. Once you open it, you’ll need to tell us:

  • your income
  • about any dependent children you have living with you, that you are the parent of (for example, a new baby with your current partner)
  • about any other children you pay or receive child support for, who are not part of the calculation.

Each child should only be listed once in the calculation.

Tell us about the other parent

Tell us:

  • the other parent’s income
  • about any dependent children they have living with them, that they are the parent of (for example, a new baby with their current partner)
  • about any other children they pay or receive child support for, who are not part of the calculation (for example, payments they make to another ex-partner.)

Each child should only be listed once in the calculation.

Tell us about your qualifying children

This means the children you want to pay or receive child support for – not any children you’ve previously listed. Tell us:

  • their names and dates of birth
  • their ongoing living arrangements – which parent do they usually live with? How many nights each week, fortnight or month?

See what your payments could be

The calculator will show what your payments could be, based on the information you’ve given.

This is a guide only and does not send any information to us.

To know for certain how much your child support would be, you would need to apply for a formula assessment.

Try the calculator

5 minutes
Child support payment calculator

Find out how much you might get or pay based on care arrangements and both parents' incomes.

Go to this tool

What happens next

If you like, you can:

  • use the suggested amount to set up a private or voluntary agreement
  • apply for a formula assessment.

Private agreements
Voluntary agreements
Apply for child support - formula assessment

Last updated: 30 Apr 2025
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