Australia 
The Child Support Agency assesses how much child support should be paid using the child support formula. Example of basic formula:
- ‘Child Support Income’ of the payer using the most recent tax return - $40,000.00
- Less ‘Exempted Income’ for a single adult (for 2002/03) - $11,740.00
- Apply the ‘Child Support percentage’ (27% for 2 children) - $7,630.20
- Amount of Child Support payable = $635.85 per month, or $146.73 per week.
The child support percentage varies between 18% to 36% according to the number of children who are the subject of the assessment.
The carer parent’s income can also affect the formula if it exceeds $35,012 (2002/03). There are more complex variations of the formula where for example:
- The payer has other "relevant dependent children" in their care (i.e. natural or adopted children).
- The care of the children is shared (more than 146 nights per year with each parent).
- The payer has substantial contact with the children (109 - 146 nights per year).
- The children of the relationship are divided between the parent’s homes.
- The payer has responsibilities to several carers for other children.
