The Child Support Agency (CSA) is an Australian Government organisation which was established in 1988 to administer the assessment and collection of child support under the Australian Government's Child Support Scheme.
The CSA is responsible for administering the Child Support (Assessment) Act 1989 which sets out the calculation of child support, based on a formula encompassing the income of the parent/s, care arrangements of the children, ages of the children, other dependents and a number of other factors; and the Child Support (Registration and Collection Act) 1988 regarding to the transfer and collection of the calculated payments, including enforcement of unpaid amounts.

The CSA has approximately 1.5 million customers and employs over 4000 staff .

While it is one of the most complained about Australian Government agencies, the Australian Child Support Agency is recognized as a world leader in terms of effectiveness and efficiency at administering child support.

The standard formula calculates the majority of the 1.5 million cases administered, the formula is set up in such a way that a new amount is generally calculated on an annual basis as incomes change and children grow older, or if there are any changes to the care arrangements, birth of new children and so on.

In some circumstances parents can make their own agreements as to what child support is paid, also there are provisions for agency review of individual formula assessments in special circumstances, and the courts may also set amounts payable should either or both parents seek a court ruling on the matter.

Transfer of payments can be made independently of the agency (approximately 46% of cases) or via the agency as either a voluntary arrangement, or through enforcement.