Sections 97 and 98 Child Support (Assessment) Act 1989
A child support agreement may be varied by:
A court can set aside a child support agreement if the agreement was obtained by fraud or undue influence.
A child support agreement can be ended by a later child support agreement which provides for the liability under the earlier agreement to end. If an end date isn't specified CSA will end the earlier agreement from the date of the later agreement.
Where a child support assessment existed immediately prior to the agreement and was modified by the agreement, the child support assessment continues when the agreement ends. CSA will assess the liability in accordance with the relevant formula, including reinstating a change of assessment decision that existed prior to the agreement.
M and F have a child support assessment. CSA makes a change of assessment decision for the period 1 July 1997 to 30 June 2000. On 1 December 1999 CSA accepts M and F's child support agreement which varies the rate of child support for the period 1 December 1998 to 30 November 1999. The child support assessment continues after the agreement ends on 30 November 1999, and the amount payable from 1 December 1999 is as provided by the change of assessment decision.
If no child support assessment was in force immediately before the agreement, the end of the agreement is a terminating event (section 12(4)).
A child support agreement provides that 'For the next 3 years M agrees to pay child support of $200 per month to F for C'. M and F had no child support assessment when M applied to CSA for acceptance of the agreement. M's liability will end 3 years after the date of the agreement.
If a liability ends it does not prevent either parent reapplying for an administrative assessment or for the acceptance of another agreement.
An agreement does not cease to be in force when a terminating event occurs (there is no corresponding provision to section 142 of the Assessment Act which says that a court order ceases to be in force when a terminating event occurs). If a carer parent later reapplies for an assessment the assessment will be made using the provisions of Part 5 of the Assessment Act as they are modified by the agreement.
If an agreement covers more than one child, and there is a terminating event for one of the children, CSA must amend the assessment to give effect to the terminating event.
If the agreement specifies the amount payable for each child, CSA will amend the assessment so that it reflects the agreed amount for the remaining children.
If the agreement simply nominates a single amount for all of the children, CSA cannot apportion the amount between the children. CSA's assessment will continue to reflect the full amount payable under the agreement. However, the parents can make a new agreement to deal with their changed circumstances.