2.4.1: The Formulas
Context
CSA will use an administrative formula to calculate the annual rate of child support payable under an administrative assessment unless:
- the assessment is varied by a departure order by a court, (see chapter 2.8.2), or
- the assessment is varied by a change of assessment decision, (see chapter 2.6), or
- the assessment is varied by the provisions of a child support agreement (See chapter 2.7.4).
Legislative references
- Section 5, Division 2 of Part 5 Child Support Assessment Act 1989
Explanation
The annual rate of child support payable is calculated using one of six formulas (section 35B). The six formulas are variations of one basic formula. To calculate a child support assessment the formulas utilise:
- the parents' incomes (refer to chapter 2.4.4, Child support income);
- the percentage of care of the child, and the percentage of the costs met by this care (refer to chapter 2.4.5, Care, cost and child support percentages); and
- the costs of the child (refer to chapter 2.4.6, The costs of the child).
For information about the tables and values used in the calculation of the assessments refer to chapter 2.4.2, Formula tables and values.
The formulas adopt an 'income shares' approach where the costs of the children are calculated based on the parents' combined income and shared between the parents in proportion to each parent's share of their combined income. Either parent may meet some or all of their share of the costs during care.
A child support case is defined as the assessments for all the children who are children of both the parents of the child (section 5). If somebody other than a parent is caring for a child then there may be three (or more) parties to a case.
In the majority of cases the rate of child support will be assessed using formula 1. The formulas are:
Formula 1 - the basic formula, for a single child support case (section 35): See chapter 2.4.7.
Formula 2 - for a single child support case with a non parent-carer (section 36): See chapter 2.4.8.
Formula 3 - if one or both of the parents have multiple child support cases (section 37): See chapter 2.4.9.
Formula 4 - if a parent has multiple child support cases and there is a non-parent carer for one or more children (section 38): See chapter 2.4.9.
Formula 5 - for a child support case with a non parent-carer where one parent is not assessed because they are not a resident of Australia or there are special circumstances (section 39): See chapter 2.4.10.
Formula 6 - for a child support case with a non parent-carer where one parent is deceased (section 40): See chapter 2.4.10.