Maintenance is always variable

When a maintenance order is in force, whether payments to a spouse for her own maintenance (‘spousal maintenance’) or payments to a spouse to help maintain a child or children (‘child maintenance’), the amount of maintenance can always be varied.  

If the circumstances of the payer or of the payee change and the amount of maintenance no longer reflects the reality of the situation, either party can apply to the court for the amount to be varied.

Almost always it is best if possible to get the amount varied by agreement rather than apply to the court.